Android 5.1 相容性定義

一、簡介

本文檔列舉了裝置與 Android 5.1 相容必須滿足的要求。

「MUST」、「MUST NOT」、「REQUIRED」、「SHALL」、「SHALL NOT」、「SHOULD」、「SHOULD NOT」、「RECOMMENDED」、「MAY」和「OPTIONAL」的使用符合 IETF 標準RFC2119 [參考資料，1 ] 中定義的標準。

在本文檔中，「裝置實施者」或「實施者」是指開發運行 Android 5.1 的硬體/軟體解決方案的個人或組織。 “設備實現”或“實現是這樣開發的硬體/軟體解決方案。

若要被視為與 Android 5.1 相容，裝置實作必須滿足此相容性定義中提出的要求，包括透過引用合併的任何文件。

如果第 10 節中所述的此定義或軟體測試是沉默的、不明確的或不完整的，則設備實現者有責任確保與現有實現的兼容性。

因此，Android 開源專案 [參考資料, 2 ] 既是 Android 的參考實現，也是首選實現。強烈鼓勵設備實現者最大程度地基於 Android 開源專案提供的「上游」原始程式碼來實現其實現。雖然假設某些組件可以替換為替代實現，但強烈建議不要這樣做，因為通過軟體測試將變得更加困難。實作者有責任確保與標準 Android 實作完全行為相容，包括相容性測試套件。最後，請注意，本文檔明確禁止某些組件替換和修改。

在第 14 節中列出的許多資源直接或間接源自 Android SDK，並且在功能上與該 SDK 文件中的資訊相同。如果本相容性定義或相容性測試套件與 SDK 文件不一致，則 SDK 文件被視為具有權威性。在第 14 節中包含的參考文獻中提供的任何技術細節均被視為包含在本相容性定義中。

2. 設備類型

雖然 Android 開源專案已用於實現各種裝置類型和外形尺寸，但架構和相容性要求的許多方面都針對手持裝置進行了最佳化。從 Android 5.0 開始，Android 開源專案旨在涵蓋本節中所述的更廣泛的裝置類型。

Android 手持裝置是指通常手持使用的 Android 裝置實現，例如 MP3 播放器、手機和平板電腦。 Android 手持裝置實作：

• 設備中必須嵌入觸控螢幕。
• 必須有提供移動性的電源，例如電池。

Android TV 裝置是指一種Android 裝置實現，它是一個娛樂介面，用於為坐在大約10 英尺外的用戶消費數位媒體、電影、遊戲、應用程式和/或直播電視（「向後靠」或“10 英尺使用者介面”） ”）。 Android 電視裝置：

• 必須具有嵌入式螢幕或包含視訊輸出端口，例如 VGA、HDMI 或用於顯示的無線端口。
• 必須聲明 android.software.leanback 和 android.hardware.type.television 功能 [參考資料，3 ]。

Android Watch 裝置是指旨在佩戴在身體上（可能戴在手腕上）的 Android 裝置實現，並且：

• 螢幕的實體對角線長度必須在 1.1 到 2.5 吋範圍內。
• 必須聲明 android.hardware.type.watch 功能。
• 必須支援 uiMode = UI_MODE_TYPE_WATCH [資源，4 ]。

Android Automotive 實作是指運行 Android 作為部分或全部系統和/或資訊娛樂功能的作業系統的車輛主機單元。 Android Automotive 實作必須支援 uiMode = UI_MODE_TYPE_CAR [資源，111 ]。

所有不適合上述任何裝置類型的 Android 裝置實作仍必須滿足本文檔中與 Android 5.1 相容的所有要求，除非該要求明確描述為僅適用於上述特定 Android 裝置類型。

2.1 設備配置

這是按設備類型劃分的硬體配置主要差異的摘要。 （空單元格表示“可以”）。此表並未涵蓋所有配置；有關更多詳細信息，請參閱相關硬體部分。

3、軟體

3.1.託管 API 相容性

託管的 Dalvik 字節碼執行環境是 Android 應用程式的主要工具。 Android 應用程式介面 (API) 是向在託管執行時間環境中運行的應用程式公開的一組 Android 平台介面。裝置實作必須提供 Android SDK [參考資料，5 ] 公開的任何記錄的 API 或上游 Android 原始碼中用「@SystemApi」標記修飾的任何 API 的完整實現，包括所有記錄的行為。

設備實作不得省略任何託管 API、更改 API 介面或簽章、偏離記錄的行為或包含無操作，除非本相容性定義明確允許。

此相容性定義允許裝置實作省略 Android 包含的 API 的某些類型的硬體。在這種情況下，API 必須仍然存在並以合理的方式運行。有關此場景的具體要求，請參閱第 7 節。

3.2.軟 API 相容性

除了第 3.1 節中的託管 API 之外，Android 還包括一個重要的僅運行時「軟」API，其形式為意圖、權限和 Android 應用程式的類似方面，這些方面無法在應用程式編譯時強制執行。

3.2.1.權限

設備實現者必須支援並強制執行權限參考頁 [參考資料，6]中記錄的所有權限常數。請注意，第 9 節列出了與 Android 安全模型相關的其他要求。

3.2.2.建構參數

Android API 在 android.os.Build 類別 [參考資料，7 ] 上包含許多常數，用於描述目前裝置。為了跨裝置實作提供一致、有意義的值，下表包含裝置實作必須遵守的這些值的格式的附加限制。

3.2.3.意圖相容性

裝置實作必須遵循 Android 的鬆散耦合意圖系統，如下節所述。 「榮幸」意味著裝置實現者必須提供一個 Android Activity 或服務，指定一個匹配的 Intent 過濾器，該過濾器綁定到每個指定的 Intent 模式並為其實現正確的行為。

3.2.3.1.核心應用意圖

Android 意圖允許應用程式元件向其他 Android 元件請求功能。 Android 上游項目包括被視為核心 Android 應用程式的應用程式列表，這些應用程式實現了多種意圖模式來執行常見操作。 Android 的核心應用程式是：

• 英式鐘
• 瀏覽器
• 日曆
• 聯絡方式
• 畫廊
• 全球搜尋
• 啟動器
• 音樂
• 設定

裝置實作應該包括適當的核心 Android 應用程序，但必須包括一個元件，該元件實現由這些核心 Android 應用程式的所有「公共」活動或服務元件定義的相同意圖模式。請注意，當屬性 android:exported 不存在或值為 true 時，Activity 或 Service 元件被視為「公有」。

3.2.3.2.意圖覆蓋

由於 Android 是一個可擴展平台，裝置實作必須允許第三方應用程式覆蓋第 3.2.3.1 節中引用的每個意圖模式。上游 Android 開源實作預設允許這樣做；設備實現者不得為系統應用程式對這些意圖模式的使用附加特殊權限，或阻止第三方應用程式綁定到這些模式並承擔對這些模式的控制。該禁止具體包括但不限於停用「選擇器」使用者介面，該介面允許使用者在全部處理相同意圖模式的多個應用程式之間進行選擇。

但是，如果預設活動為資料 URI 提供更具體的篩選器，則裝置實作可以為特定 URI 模式（例如 http://play.google.com）提供預設活動。例如，指定資料 URI「http://www.android.com」的意圖過濾器比瀏覽器過濾器「http://」更具體。設備實作必須為使用者提供一個使用者介面來修改意圖的預設活動。

3.2.3.3.意圖命名空間

裝置實作不得包含任何使用 Android.* 或 com.android.* 命名空間中的 ACTION、CATEGORY 或其他鍵字串來支援任何新意圖或廣播意圖模式的 Android 元件。裝置實現者不得包含任何使用 ACTION、CATEGORY 或屬於另一個組織的套件空間中的其他關鍵字串來遵循任何新意圖或廣播意圖模式的 Android 元件。設備實現者不得更改或擴展第 3.2.3.1 節中列出的核心應用程式使用的任何意圖模式。設備實作可以包括使用與其自己的組織明確相關的命名空間的意圖模式。該禁止類似於3.6 節中針對 Java 語言類別指定的禁止。

3.2.3.4.廣播意圖

第三方應用程式依靠平台廣播某些意圖，以通知它們硬體或軟體環境的變化。 Android 相容裝置必須廣播公共廣播意圖以回應適當的系統事件。 SDK 文件中描述了廣播意圖。

3.2.3.5.預設應用程式設定

Android 包含的設定可讓用戶輕鬆選擇預設應用程序，例如主螢幕或簡訊。在有意義的情況下，設備實作必須提供類似的設定選單，並與 SDK 文件中所述的意圖過濾器模式和 API 方法相容，如下所示。

設備實現：

• 如果裝置實作報表 android.software.home_screen [資源，10] ，則必須遵守 android.settings.HOME_SETTINGS 意圖，以顯示主畫面的預設應用程式設定選單
• 如果裝置實作報表 android.hardware.telephony [資源，9 ]，則必須提供一個設定選單，該選單將呼叫 android.provider.Telephony.ACTION_CHANGE_DEFAULT 意圖來顯示一個對話框以變更預設 SMS 應用程式
• 如果裝置實作報表 android.hardware.nfc.hce，則必須遵守 android.settings.NFC_PAYMENT_SETTINGS 意圖，以顯示點擊付款的預設應用程式設定選單 [資源，10]

3.3.本機 API 相容性

3.3.1.應用程式二進位接口

託管 Dalvik 字節碼可以呼叫應用程式 .apk 檔案中提供的本機程式碼，作為針對適當裝置硬體架構編譯的 ELF .so 檔案。由於本機程式碼高度依賴底層處理器技術，Android 在 Android NDK 中定義了許多應用程式二進位介面 (ABI)。裝置實作必須與一個或多個定義的 ABI 相容，並且必須實現與 Android NDK 的兼容性，如下所示。

如果裝置實現包含對 Android ABI 的支持，則：

• 必須支援在託管環境中執行的程式碼，以使用標準 Java 本機介面 (JNI) 語義呼叫本機程式碼
• 必須與下面列表中每個所需的庫來源相容（即標頭相容）和二進位相容（對於 ABI）
• 如果支援任何 64 位元 ABI，則必須支援等效的 32 位元 ABI
• 必須透過 android.os.Build.SUPPORTED_ABIS、android.os.Build.SUPPORTED_32_BIT_ABIS 和 android.os.Build.SUPPORTED_64_BIT_ABIS 參數準確報告裝置支援的本機應用程式二進位介面 (ABI)，每個清單都是逗號分隔的ABI 從最受青睞的到最不受青睞的排序
• 必須透過上述參數僅報告最新版本的 Android NDK（《NDK 程式設計師指南 | NDK 程式設計師指南》）中記錄的 ABI。 ABI 管理」位於 docs/ 目錄中
• 應使用上游 Android 開源專案中提供的源代碼和頭文件進行構建

以下本機程式碼 API 必須可用於包含本機程式碼的應用程式：

• libc（C 庫）
• libm（數學庫）
• 對 C++ 的最低支持
• JNI介面
• liblog（Android 日誌記錄）
• libz（Zlib 壓縮）
• libdl（動態連結器）
• libGLESv1_CM.so (OpenGL ES 1.x)
• libGLESv2.so（OpenGL ES 2.0）
• libGLESv3.so (OpenGL ES 3.x)
• libEGL.so（原生 OpenGL 表面管理）
• libjnigraphics.so
• libOpenSLES.so（OpenSL ES 1.0.1 音訊支援）
• libOpenMAXAL.so（OpenMAX AL 1.0.1 支援）
• libandroid.so（原生 Android 活動支援）
• libmediandk.so（原生媒體 API 支援）
• 支援 OpenGL，如下所述

請注意，Android NDK 的未來版本可能會引入對其他 ABI 的支援。如果設備實作與現有的預定義 ABI 不相容，則它根本無法報告對任何 ABI 的支援。

請注意，裝置實作必須包含 libGLESv3.so，並且它必須符號連結（符號連結）到 libGLESv2.so。反過來，必須匯出 NDK 版本 android-21 中定義的所有 OpenGL ES 3.1 和 Android 擴充包 [資源，11 ] 函數符號。儘管所有符號都必須存在，但只有裝置實際支援的 OpenGL ES 版本和擴充功能的相應功能必須完全實作。

本機程式碼相容性具有挑戰性。因此，強烈鼓勵裝置實現者使用上游 Android 開源專案中列出的上述程式庫的實作。

3.3.2. 32 位元 ARM 本機程式碼相容性

ARMv8 架構棄用了多個 CPU 操作，包括現有本機程式碼中使用的一些操作。在 64 位元 ARM 裝置上，透過本機 CPU 支援或透過軟體模擬，以下已棄用的操作必須對 32 位元本機 ARM 程式碼保持可用：

• SWP 和 SWPB 指令
• 設定指令
• CP15ISB、CP15DSB 和 CP15DMB 屏障操作

舊版 Android NDK 使用 /proc/cpuinfo 從 32 位元 ARM 本機程式碼發現 CPU 功能。為了與使用此 NDK 建置的應用程式相容，當 32 位元 ARM 應用程式讀取 /proc/cpuinfo 時，裝置必須在 /proc/cpuinfo 中包含以下行：

• “功能：”，後跟裝置支援的任何可選 ARMv7 CPU 功能的列表
• “CPU 架構：”，後面跟著一個整數，描述裝置支援的最高 ARM 架構（例如，“8”表示 ARMv8 裝置）

這些要求僅在 32 位元 ARM 應用程式讀取 /proc/cpuinfo 時適用。當 64 位元 ARM 或非 ARM 應用程式讀取 /proc/cpuinfo 時，裝置不應變更。

3.4.網路相容性

3.4.1.網頁視圖相容性

平台功能 android.software.webview 必須在提供 android.webkit.WebView API 完整實作的任何裝置上報告，且不得在沒有完整 API 實作的裝置上報告。 Android 開源實作使用 Chromium 專案中的程式碼來實作 android.webkit.WebView [參考資料，12 ]。由於為 Web 渲染系統開發全面的測試套件是不可行的，因此設備實作者必須在 WebView 實作中使用 Chromium 的特定上游版本。具體來說：

• 裝置 android.webkit.WebView 實作必須基於 Android 5.1 上游 Android 開源專案的 Chromium 建置。此版本包括一組針對 WebView 的特定功能和安全修復程序 [參考資料，13 ]。
• WebView 報告的用戶代理字串必須採用以下格式：

  Mozilla/5.0 (Linux; Android $(VERSION); $(MODEL) Build/$(BUILD)$(WEBVIEW)) AppleWebKit/537.36（KHTML，如 Gecko）版本/4.0 $(CHROMIUM_VER) Mobile Safari/537.36

  • $(VERSION) 字串的值必須與 android.os.Build.VERSION.RELEASE 的值相同。
  • $(WEBVIEW) 字串可以省略，但如果包含，則必須為「; wv」以表示這是 webview
  • $(MODEL) 字串的值必須與 android.os.Build.MODEL 的值相同。
  • $(BUILD) 字串的值必須與 android.os.Build.ID 的值相同。
  • $(CHROMIUM_VER) 字串的值必須是上游 Android 開源專案中 Chromium 的版本。
  • 設備實作可以在用戶代理字串中省略 Mobile。

WebView 元件應該包含對盡可能多的 HTML5 功能的支持，並且如果它支援該功能，則應該符合 HTML5 規範 [參考資料，14 ]。

3.4.2.瀏覽器相容性

獨立瀏覽器可以基於 WebKit 以外的瀏覽器技術。但是，即使使用備用瀏覽器應用程序，提供給第三方應用程式的 android.webkit.WebView 元件也必須基於 WebKit，如3.4.1 節中所述。

實作可以在獨立的瀏覽器應用程式中提供自訂使用者代理字串。

獨立的瀏覽器應用程式（無論是基於上游 WebKit 瀏覽器應用程式還是第三方替代品）應該盡可能支援 HTML5 [參考資料，14 ]。設備實作至少必須支援與 HTML5 相關的每個 API：

• 應用程式快取/離線操作 [資源，15 ]
• <video> 標籤 [資源，16 ]
• 地理定位 [資源，17 ]

此外，設備實作必須支援 HTML5/W3C webstorage API [參考資料，18 ]，並且應該支援 HTML5/W3C IndexedDB API [參考資料，19 ]。請注意，隨著 Web 開發標準機構逐漸轉向支援 IndexedDB 而不是 Webstorage，IndexedDB 預計將成為 Android 未來版本中的必要組件。

3.5. API 行為相容性

每個 API 類型（託管、軟體、本機和 Web）的行為必須與上游 Android 開源專案的首選實作一致 [參考資料, 2 ]。一些特定的兼容性領域是：

• 設備不得更改標準意圖的行為或語意。
• 設備不得更改特定類型的系統元件（例如服務、活動、ContentProvider 等）的生命週期或生命週期語意。
• 設備不得更改標準權限的語意。

上面的列表並不全面。相容性測試套件 (CTS) 測試平台的重要部分（但不是全部）的行為相容性。實作者有責任確保與 Android 開源專案的行為相容性。因此，裝置實現者應該盡可能使用透過 Android 開源專案提供的原始程式碼，而不是重新實作系統的重要部分。

3.6. API命名空間

Android 遵循 Java 程式語言定義的套件和類別命名空間約定。為了確保與第三方應用程式的相容性，裝置實作者不得對這些套件命名空間進行任何禁止的修改（見下文）：

• java.*
• javax.*
• 太陽。*
• 安卓。*
• com.android.*

禁止的修改包括：

• 裝置實作不得透過更改任何方法或類別簽名，或刪除類別或類別欄位來修改 Android 平台上公開的 API。
• 設備實作者可以修改 API 的底層實現，但此類修改不得影響任何公開暴露的 API 的規定行為和 Java 語言簽章。
• 設備實作者不得為上述 API 新增任何公開暴露的元素（例如類別或接口，或現有類別或介面的欄位或方法）。

「公開暴露的元素」是指未使用上游 Android 原始碼中使用的「@hide」標記修飾的任何構造。換句話說，設備實現者不得公開新的 API 或更改上述命名空間中的現有 API。設備實現者可以進行僅限內部的修改，但這些修改不得公佈或以其他方式暴露給開發人員。

設備實作者可以新增自訂 API，但任何此類 API 不得位於另一個組織擁有或引用另一個組織的命名空間中。例如，裝置實作者不得將 API 新增至 com.google.* 或類似的命名空間：只有 Google 可以做到。同樣，Google 不得將 API 新增至其他公司的命名空間。此外，如果裝置實作包含標準Android 命名空間以外的自訂API，則這些API 必須打包在Android 共用程式庫中，以便只有明確使用它們（透過<uses-library> 機制）的應用程式才會受到內存使用量增加的影響此類 API。

如果設備實現者建議改進上述包命名空間之一（例如透過向現有 API 添加有用的新功能，或添加新 API），則實現者應該訪問source.android.com並開始貢獻更改和的過程代碼，根據該網站上的信息。

請注意，上述限制對應於 Java 程式語言中命名 API 的標準約定；本節的目的只是為了加強這些約定，並透過將其納入此相容性定義來使其具有約束力。

3.7.運行時相容性

設備實作必須支援完整的 Dalvik 可執行檔 (DEX) 格式以及 Dalvik 字節碼規格和語意 [參考資料, 20 ]。設備實作者應該使用 ART、Dalvik 可執行格式的參考上游實作以及參考實作的套件管理系統。

裝置實作必須配置 Dalvik 運行時以根據上游 Android 平台分配內存，並如下表所示。 （有關螢幕尺寸和螢幕密度定義，請參閱第 7.1.1 節。）

請注意，下面指定的記憶體值被視為最小值，設備實作可以為每個應用程式分配更多記憶體。

3.8.使用者介面相容性

3.8.1.啟動器（主螢幕）

Android 包括啟動器應用程式（主畫面）並支援第三方應用程式來取代裝置啟動器（主畫面）。允許第三方應用程式替換裝置主畫面的裝置實作必須聲明平台功能 android.software.home_screen。

3.8.2.小部件

Android 定義了元件類型以及相應的 API 和生命週期，允許應用程式向最終用戶公開「AppWidget」[參考資料，21 ]，強烈建議手持裝置實作支援該功能。支援在主畫面上嵌入小工具的裝置實作必須滿足以下要求並聲明對平台功能 android.software.app_widgets 的支援。

• 裝置啟動器必須包含對 AppWidget 的內建支持，並公開使用者介面功能以直接在啟動器內新增、配置、檢視和刪除 AppWidget。
• 設備實作必須能夠渲染標準網格大小為 4 x 4 的小工具。有關詳細信息，請參閱 Android SDK 文件 [參考資料，21 ] 中的應用程式小工具設計指南。
• 包括鎖定螢幕的支援的裝置實作可以支援鎖定螢幕上的應用程式小工具。

3.8.3.通知

Android 包含的 API 允許開發人員使用裝置的硬體和軟體功能來通知使用者值得注意的事件 [參考資料，22 ]。

某些 API 允許應用程式使用硬體（特別是聲音、振動和燈光）執行通知或吸引註意。設備實作必須支援使用硬體功能的通知，如 SDK 文件所述，並儘可能支援設備實現硬體。例如，如果裝置實作包含振動器，則它必須正確實作振動 API。如果設備實作缺少硬件，則對應的 API 必須實作為無操作。此行為在第 7 節中有進一步詳細介紹。

此外，此實作必須正確渲染API [資源，23 ]或狀態/系統欄圖標樣式指南[資源，24 ]中提供的所有資源（圖標，動畫檔案等） Android電視設備包括不顯示通知的可能性。設備實施者可以為通知提供替代使用者體驗，而不是參考Android開源實作。但是，此類替代通知系統必須如上所述支援現有的通知資源。

Android包括對各種通知的支持，例如：

• 豐富的通知。持續通知的互動視圖。
• 主題通知。互動式視圖使用者可以在不留下當前應用程式的情況下採取行動或解散。
• 鎖定通知。在鎖定螢幕上顯示的通知具有可見性的顆粒狀控制。

Android裝置實作（當使此類通知都可見時，必須正確執行富富函數，並包括標題/名稱，圖標，Android API中記錄的文字[Resources，25] 。

Android包括通知偵聽器服務API，該API允許應用程式（一旦用戶明確啟用了）在發布或更新時會收到所有通知的副本。裝置實作必須正確且迅速將通知完整傳送至所有此類安裝和啟用使用者的偵聽器服務，包括附加到Notification物件的所有元資料。

3.8.4.搜尋

Android包括API [ Resources，26 ]，允許開發人員將搜尋納入其應用程序，並將其應用程式的資料曝光到全球系統搜尋。一般而言，此功能由一個單一的，全系統的使用者介面組成，該介面允許使用者輸入查詢，將建議顯示為使用者類型並顯示結果。 Android API允許開發人員重複使用此介面以在自己的應用程式中提供搜索，並允許開發人員為常見的全域搜尋使用者介面提供結果。

Android設備實現應包括全局搜索，一個單一，共享的，系統範圍的搜索用戶界面，能夠響應用戶輸入來實時建議。設備實作應實作API，允許開發人員重複使用此使用者介面以在自己的應用程式中提供搜尋。實現全域搜尋介面的裝置實作必須實作允許第三方應用程式以在全域搜尋模式運行時將建議新增至搜尋框的API。如果未安裝使用此功能的第三方應用程序，則預設行為應顯示Web搜尋引擎結果和建議。

3.8.5。吐司

應用程式可以使用「吐司」 API向最終用戶顯示短的非模式字串，該字串在短時間後消失[資源，27 ]。設備實現必須以某種高可見性顯示從應用程式到最終用戶的吐司。

3.8.6。主題

Android提供了「主題」作為應用程式在整個活動或應用程式中應用樣式的機制。

Android包含一個「 Holo」主題家族，作為一組定義樣式，供應用程式開發人員使用Android SDK所定義的Holo主題外觀和感覺[ Resources，28 ]。設備實作不得改變暴露於應用程式的任何Holo主題屬性[資源，29 ]。

Android包括一個“材料”主題家族，作為一組定義樣式，如果應用程式開發人員想在各種不同的Android設備類型中匹配設計主題的外觀和感覺，則使用。設備實現必須支援「材料」主題家族，且不得更改任何材料主題屬性或暴露於應用程式的資產[資源，30 ]。

Android還包括一個「裝置預設」主題家族，作為一組定義樣式，供應用程式開發人員使用裝置實現者定義的裝置主題的外觀和感覺，以便使用。設備實作可能會修改裝置預設主題屬性暴露於應用程式[資源，29 ]。

Android以半透明的系統列支援一個新的變體主題，該主題允許應用程式開發人員使用其應用程式內容填充狀態和導覽列背後的區域。為了在此配置中啟用一致的開發人員體驗，重要的是，在不同的裝置實作之間保持狀態列圖示樣式。因此，除非圖示指示有問題的狀態，否則Android設備實作必須將白色用於系統狀態圖示（例如訊號強度和電池等級）和系統發出的通知[資源，29 ]。

3.8.7.動態壁紙

Android定義了一種元件類型和相應的API和生命週期，該應用程式允許應用程式將一個或多個「即時桌布」暴露於最終用戶[ Resources，31 ]。即時壁紙是動畫，圖案或類似的圖像，其輸入功能有限，顯示為牆紙，在其他應用程式後面。

如果硬體可以運行所有即時壁紙，則可以可靠地運行即時壁紙，而沒有對功能的限制，以合理的幀速率對其他應用沒有不利影響。如果硬體中的限制導致壁紙和/或應用程式崩潰，故障，消耗過多的CPU或電池電量，或以不可接受的較低幀速率運行，則該硬體被認為無法運行Live Wallpaper。例如，某些即時壁紙可以使用OpenGL 2.0或3.X上下文渲染其內容。實時壁紙不會在不支援多個OpenGL上下文的硬體上可靠地運行，因為OpenGL上下文的即時壁紙使用可能與也使用OpenGL上下文的其他應用程式相抵觸。

如上所述，能夠可靠地運行即時壁紙的設備實現應實現即時壁紙，並且在實施後必須報告平台功能flag android.software.live_wallpaper。

3.8.8。活動切換

上游Android原始碼包括概述畫面[ Resources，32 ]，這是一個系統級使用者介面，用於任務切換和顯示最近訪問的活動和任務，並使用應用程式圖形狀態的縮圖映像在使用者上次離開應用程序時。設備實作包括第7.2.3節中詳細列出的RECENTS功能導航密鑰可能會更改接口，但必須滿足以下要求：

• 必須顯示關聯的恢復作為一個一起移動的群組。
• 必須至少支援多達20個顯示的活動。
• 至少應該一次顯示4個活動的標題。
• 應顯示重點，圖標，螢幕標題。
• 必須實現螢幕固定行為[資源，33 ]，並為使用者提供設定選單以切換該功能。
• 應顯示關閉負擔（“ x”），但可能會延遲此直到使用者與螢幕互動。

強烈鼓勵設備實現用於概述螢幕上游Android使用者介面（或類似的基於縮圖的介面）。

3.8.9.輸入管理

Android包括支援輸入管理和對第三方輸入方法編輯器的支援[資源，34 ]。允許使用者在裝置上使用第三方輸入方法的裝置實作必須聲明平台功能android.software.input_methods並支援Android SDK文件中定義的IME API。

聲明Android.software.input_methods功能的裝置實作必須提供可新增和設定第三方輸入方法的使用者存取機制。裝置實作必須根據android.settings.input_method_settings的意圖顯示設定介面。

3.8.10。鎖定螢幕媒體控制

遠端控制用戶端API已從Android 5.0中棄用，而有利於媒體通知模板，該模板允許媒體應用程式與鎖定螢幕上顯示的播放控制項整合[ Resources，35 ]。支援鎖定螢幕的裝置實現，除非Android Automotive或Watch實現，否則必須顯示包括媒體通知範本在內的鎖定通知。

3.8.11。夢

Android包括對稱為Dreams的互動式螢幕保護程式的支援[ Resources，36 ]。當連接到電源的設備空閒或停靠在桌上碼頭中時，夢想使用戶可以與應用程式互動。 Android Watch設備可能會實現夢想，但是其他類型的設備實現應包括對夢想的支持，並為用戶提供設定選項，以響應Android.settings.dream_settings的意圖來配置夢想。

3.8.12。地點

當設備具有能夠提供位置座標的硬體感測器（例如GPS）時，必須在設定中的位置選單中顯示位置模式[ Resources，37 ]。

3.8.13。 Unicode和字體

Android包含對顏色表情符號字元的支援。當Android裝置實作包含IME時，裝置應為Unicode 6.1中定義的表情符號字元的使用者提供輸入方法[ Resources，38 ]。所有設備都必須能夠在顏色字形中呈現這些表情符號字元。

Android包括對具有不同重量的Roboto 2字體的支援-Sans-serif-shin，sans-serif-light，sans-serif-medium，sans sans-serif-black，sans-sers-serif-serif-wondensed，sans- sans-serif-serif-serif-densed-wighted-light-wher必須全部包含在設備上可用的語言和拉丁語，希臘和西里爾的完整Unicode 7.0覆蓋範圍，包括拉丁語擴展A，B，C和D範圍，以及Unicode 7.0的貨幣符號區塊中的所有字形。

3.9.設備管理

Android包含允許安全感知應用程式在系統層級執行裝置管理功能的功能，例如執行密碼原則或透過Android裝置管理API執行遠端抹除[ Resources，39 ]。設備實作必須提供設備上的PolicyManager類別的實作[ Resources，40 ]。設備實現包括對PIN（數字）或密碼（字母數字）的鎖定螢幕的支持，必須支援Android SDK文件中定義的設備管理策略[ Resources，39 ]，並報告平台功能Android.software.device.device_admin。

設備實作可能具有預先安裝的應用程式執行裝置管理功能，但不得將此應用程式設定為預設裝置所有者應用程式[ Resources，41 ]。

3.10.無障礙

Android提供了一個可訪問性層，可幫助殘疾用戶更輕鬆地導航其裝置。此外，Android還提供了平台API，使可訪問性服務實現能夠接收用於用戶和系統事件的回調，並產生替代的反饋機制，例如文字轉語音，觸覺反饋，軌跡球/D-Pad導航[ Resources ，42 ]。

設備實現包括以下要求：

• Android Automotive實作應提供與預設Android實作一致的Android可訪問性框架的實作。
• 設備實作（不包括Android汽車）必須提供與預設的Android實作一致的Android可訪問性框架的實作。
• 設備實作（不包括Android汽車）必須支援透過Android.Ascorsibilityservice API [ Resources，43 ]的第三方可訪問性服務實作。
• 設備實現（排除Android汽車）必須產生可訪問性，並以與預設的Android實現一致的方式將這些事件交付給所有註冊的可訪問性服務實現
• 設備實作（Android Automotive和Android Watch設備，不包括音訊輸出），必須提供可啟用和停用可存取性服務的使用者存取機制，並且必須對Android.provider.settings.action.action_accessibility_settings的意圖顯示此介面。

此外，設備實現應在設備上提供可訪問性服務的實現，並應為使用者提供在設備設定期間啟用可訪問性服務的機制。可訪問性服務的開源實施可從眼睛免費專案[ Resources，44 ]。

3.11.文字轉語音

Android包括允許應用程式使用文字轉語音（TTS）服務的API，並允許服務提供者提供TTS服務的實現[ Resources，45 ]。裝置實作報表功能Android.hardware.audio.Output必須符合與Android TTS框架相關的這些要求。

Android汽車實施：

• 必須支援Android TTS框架API。
• 可能支援安裝第三方TTS引擎。如果得到支持，合作夥伴必須提供一個可存取用戶的接口，該接口允許用戶選擇用於系統級別的TTS引擎。

所有其他設備實作：

• 必須支援Android TTS框架API，並應包括支援裝置上可用語言的TTS引擎。請注意，上游Android開源軟體包含功能齊全的TTS引擎實作。
• 必須支援安裝第三方TTS發動機
• 必須提供一個可訪問用戶的接口，該接口允許用戶選擇用於系統級別的TTS引擎

3.12.電視輸入框架

Android電視輸入框架（TIF）簡化了直播內容到Android電視裝置的交付。 TIF提供了一個標準API來建立控制Android電視裝置的輸入模組。 Android電視設備實作必須支援電視輸入框架[資源，46 ]。

支援TIF的裝置實作必須聲明平台功能Android.software.live_tv。

4. 應用程式封裝相容性

設備實作必須安裝並運行由官方Android SDK中包含的「 AAPT」工具產生的Android「 .APK」檔案[ Resources，47 ]。

設備實作不得擴展.APK [資源，48 ]，Android清單[資源，49 ]，Dalvik bytecode [ Resources，20 ]或RenderScript字節碼的格式，以防止這些文件安裝並在其他兼容設備。

5.多媒體相容性

5.1.媒體編解碼器

設備實作必須支援Android SDK文件中指定的核心媒體格式[資源，50 ]，除非本文檔明確允許。具體而言，設備實作必須支援媒體格式，編碼器，解碼器，檔案類型和容器格式在下表中定義，並透過MediaCodeClist [ Resources，112 ]進行了報告。設備實作也必須能夠解碼其CamcorderProfile中報告的所有設定檔[ Resources，113 ]。所有這些編解碼器都是在Android開源專案的首選Android實作中作為軟體實現的。

請注意，Google和開放手機聯盟都沒有做出任何代碼器，即這些編解碼器沒有第三方專利。建議打算在硬體或軟體產品中使用此原始碼的人，該程式碼的實現（包括開源軟體或共享軟體）可能需要相關專利持有人的專利許可。

5.1.1.音訊編解碼器

1定義Android.hardware.microphone但可選的Android Watch設備實現的設備實現所需的1。

2僅需5.0/5.1內容的下降；錄製或渲染超過2個頻道是可選的。

3 Android手持裝置實現所需。

4定義Android.hardware.microphone（包括Android Watch設備實作）所需的設備實作所需。

5.1.2.圖像編解碼器

5.1.3.視訊編解碼器

視訊編解碼器對於Android Watch設備實作是可選的。

1設備實現所需的，包括相機硬體並定義Android.hardware.Camera或Android.hardware.Camera.Front。

2設備實現所需的2。

3對於Web視訊串流和視訊會議服務的可接受質量，設備實現應使用符合[資源，51 ]中要求的硬體VP8編解碼器。

4設備實作應支援編寫Matroska WebM文件。

5強建議用於Android汽車，可選的Android手錶，並且所有其他設備類型都需要。

5.2.視訊編碼

具有H.264編解碼器​​支援的Android設備實現，必須支援基線設定檔等級3和以下SD（標準定義）視訊編碼設定文件，並應支援主配置級4和以下HD（高清）視訊編碼設定檔。強烈建議使用Android電視設備以30 fps編碼HD 1080p視訊。

1當由硬體支援時，但強烈建議用於Android電視設備。

具有VP8編解碼器支援的Android設備實作必須支援SD視訊編碼設定文件，並應支援以下HD（高畫質）視訊編碼設定檔。

1當硬體支援時。

5.3.視訊解碼

設備實作必須支援所有VP8，VP9，H.264和H.265編解碼器在同一流中的動態視訊解析度切換，並透過標準的Android API暴露於開發人員。

使用H.264解碼器的Android設備實現，必須支援基線設定檔3和以下SD視訊解碼設定文件，並應支援HD解碼設定檔。 Android電視裝置必須支援高調4.2和HD 1080p解碼設定檔。

1 Android電視設備實現所需的1，但僅在硬體支援時才用於其他設備類型。

2 Android電視裝置實現所需。

如第5.1.3節所述支援VP8編解碼器時，Android設備實作必須支援下列SD解碼設定文件，並應支援HD解碼設定檔。 Android電視裝置必須支援HD 1080p解碼設定檔。

Android電視裝置實現所需的1個，但僅在由硬體支援時才用於其他類型的裝置。

2 Android電視裝置實現所需。

如第5.1.3節所述支援VP9編解碼器時，Android設備實作必須支援下列SD視訊解碼設定文件，並應支援HD解碼設定檔。強烈建議使用Android電視設備來支援HD 1080p解碼設定文件，並應支援UHD解碼設定檔。當支援UHD視訊解碼設定檔時，它必須支援8位元顏色深度。

Android電視裝置實現所需的1個，但僅在由硬體支援時才用於其他類型的裝置。

2在由硬體支援時，強烈建議用於Android電視設備實現。

如第5.1.3節所述支援H.265編解碼器時，Android設備實作必須支援主設定檔3主層和以下SD視訊解碼設定文件，並應支援HD解碼設定檔。 Android電視裝置應支援MAIN10 5級主層設定檔和UHD解碼設定檔。強烈建議使用Android電視設備來支援HD 1080p解碼設定檔。如果支援HD 1080p解碼設定文件，則必須支援主設定檔4.1主層

1 Android電視設備實現所需的1，但僅在由硬體支援時才用於其他類型的設備。

2在由硬體支援時，強烈建議用於Android電視設備實現。

5.4.聲音錄製

雖然本節中概述的某些要求是自Android 4.3以來應該說的，但計劃將來版本的兼容性定義將其更改為必須。強烈建議使用現有的和新的Android設備來滿足應按應有的規定的要求，或者在升級到將來版本時，它們將無法達到Android相容性。

5.4.1.原始音訊捕獲

聲明Android.hardware.microphone的裝置實作必須允許擷取具有以下特徵的原始音訊內容：

• 格式：線性PCM，16位
• 取樣率：8000，11025，16000，44100
• 頻道：單聲道

聲明Android.hardware.microphone的裝置實作應允許擷取具有以下特徵的原始音訊內容：

• 格式：線性PCM，16位
• 取樣率：22050，48000
• 頻道：立體聲

5.4.2.捕捉語音識別

除上述記錄規格外，當應用程式開始使用android.media.mediarecorder.audiosource.voice_recognition Audio來源來錄製音訊串流時，

• 該設備應顯示大致平坦的幅度與頻率特徵：具體來說，±3 dB，從100 Hz到4000 Hz。
• 應該設定音頻輸入靈敏度，以使1000 Hz的90 dB聲音源（SPL）源可為16位元樣品產生2500的RMS。
• PCM振幅水平應線性追蹤至少30 dB上的SPL變化，從-18 dB到+12 dB re 90 dB re 90 dB spl在麥克風上。
• 在麥克風處，在90 dB的SPL輸入水準下，1KHz的總諧波失真應小於1％。
• 降噪處理，如果存在，則必須停用。
• 自動增益控制（如果存在）必須停用

如果該平台支援抑制語音辨識的噪音抑制技術，則該效果必須從android.media.audiofx.noisesuppressor API中控制。此外，噪音抑制器效果描述符的UUID欄位必須唯一確定噪音抑制技術的每個實作。

5.4.3.捕獲重新播放

android.media.mediarecorder.audiosource類別包含遠端_submix音訊來源。宣告Android.hardware.Audio.Output的裝置必須正確實作remote_submix音訊來源，以便應用程式使用android.media.media.audiorecord api從此音訊來源記錄時，它可以擷取所有音訊串流的混音:

• stream_ring
• stream_alarm
• stream_notification

5.5.音訊播放

聲明Android.hardware.audio.Output的裝置實作必須符合本節中的要求。

5.5.1.原始音訊播放

該設備必須允許具有以下特徵的原始音訊內容播放：

• 格式：線性PCM，16位
• 取樣率：8000，11025，16000，22050，32000，44100
• 頻道：單，立體聲

該設備應允許播放具有以下特徵的原始音訊內容：

• 取樣率：24000，48000

5.5.2.音訊效果

Android為裝置實作提供了音訊效果的API [資源，52 ]。聲明功能Android.hardware.audio.Output的裝置實作：

• 必須支援效果_type_equalizer和效果_type_loudness_enhancer實作可透過音頻效應子類均衡器Louynessenhancer控制。
• 必須支援可視化器API實現，該實現可透過可視化器類別控制。
• 應支援效果_TYPE_BASS_BOOST，效果_TYPE_ENV_REVERB，FEMPLECT_TYPE_PRESET_REVERB和FENSCER_TYPE_TYPE_VIRTUALIZER實作可透過Audioeffect子類別Bassboost，EmoventerAlvironingAlreReverb，PresetRever

5.5.3.音訊輸出量

Android電視設備的實現必須包括對支援輸出的系統主音量和數位音訊輸出量衰減的支持，除了壓縮音訊傳遞輸出（在設備上未完成音訊解碼）。

5.6.音訊延遲

音訊延遲是隨著音訊訊號通過系統的時間延遲。許多類別的應用程式都依賴短延遲來實現即時聲音效果。

出於本節的目的，請使用以下定義：

• 輸出延遲。當應用程式寫入PCM編碼資料的框架與外部偵聽器可以聽到相應的聲音或感測器觀察到相應的聲音時，間隔。
• 冷輸出潛伏期。當音訊輸出系統閒置並在請求之前降低電源時，第一幀的輸出延遲。
• 連續輸出延遲。設備播放音訊後，後續幀的輸出延遲。
• 輸入延遲。將外部聲音呈現給裝置的間隔與應用程式讀取PCM編碼資料的對應影格時的間隔。
• 冷輸入延遲。遺失的輸入時間和第一幀的輸入延遲的總和，當音訊輸入系統閒置並在請求之前停止電源。
• 連續輸入延遲。設備擷取音訊時，後續幀的輸入延遲。
• 冷輸出抖動。冷輸出延遲值的單獨測量值之間的差異。
• 冷輸入抖動。冷輸入延遲值的單獨測量值之間的差異。
• 連續的往返潛伏期。連續輸入延遲加連續輸出延遲加5毫秒的總和。
• OpenSL ES PCM緩衝液佇列API 。 Android NDK中的PCM相關的OPESL ES API集；請參閱ndk_root/doc/opensles/index.html。

聲明Android.hardware.audio.Output的裝置實作應滿足或超過以下音訊輸出要求：

• 100毫秒或更少的冷輸出潛伏期
• 連續輸出潛伏期為45毫秒或更少
• 最小化冷輸出抖動

如果裝置實現在使用OpenSL ES PCM緩衝區佇列API時進行任何初始校準後滿足本節的要求，則在至少一個支援的音訊輸出裝置上，對於連續輸出延遲和冷輸出潛伏期，它可能會報告對低延遲音訊的支持，透過報告android.audio.low_latency的功能，透過android.content.pm.packagemanager類別[ Resources，53 ]。相反，如果設備實現不符合這些要求，則不得報告對低延遲音訊的支援。

包括android.hardware.microphone在內的裝置實作應滿足以下輸入音訊要求：

• 100毫秒或更少的冷輸入潛伏期
• 連續輸入潛伏期為30毫秒或更少
• 連續50毫秒或更少的往返潛伏期
• 最大程度地減少冷輸入抖動

5.7.網路協定

設備必須支援Android SDK文件[資源，50 ]中指定的音訊和視訊播放的媒體網路協定。具體而言，設備必須支援以下媒體網路協定：

• RTSP（RTP，SDP）
• HTTP（S）漸進式串流媒體
• HTTP（S）即時串流協議，版本3 [資源，54 ]

5.8.安全媒體

支援安全視訊輸出並且能夠支援安全表面的裝置實作必須聲明對display.flag_secure的支援。聲明支援Display.flag_secure的設備實現，如果它們支援無線顯示協議，則必須使用密碼強的機制（例如HDCP 2.x或更高）來保護鏈接，以供Miracast Wireless顯示器。同樣，如果它們支援有線外部顯示，則設備實作必須支援HDCP 1.2或更高。 Android Television設備實作必須支援HDCP 2.2，用於支援4K解析度和HDCP 1.4或更高的設備，以供較低的解析度。上游Android開源實作包括滿足此要求的無線（Miracast）和有線（HDMI）顯示的支援。

6. 開發者工具和選項相容性

6.1.開發者工具

設備實作必須支援Android SDK中提供的Android開發人員工具。 Android相容裝置必須與：

• Android調試橋（ADB） [資源，55 ]

設備實作必須支援Android SDK中記錄的所有ADB功能，包括Dumpsys [資源，56 ]。預設情況下，裝置側ADB守護程式必須不活動，並且必須有一個可存取使用者的機制來開啟Android偵錯橋。如果裝置實作省略了USB週邊模式，則必須透過本地區域網路（例如乙太網路或802.11）實作Android調試橋。

Android包含安全ADB的支援。 Secure adb enables adb on known authenticated hosts. Device implementations MUST support secure adb.

• Dalvik Debug Monitor Service (ddms) [ Resources, 57 ]

Device implementations MUST support all ddms features as documented in the Android SDK. As ddms uses adb, support for ddms SHOULD be inactive by default, but MUST be supported whenever the user has activated the Android Debug Bridge, as above.

• Monkey [ Resources, 58 ]

Device implementations MUST include the Monkey framework, and make it available for applications to use.

• SysTrace [ Resources, 59 ]

Device implementations MUST support systrace tool as documented in the Android SDK. Systrace must be inactive by default, and there MUST be a user-accessible mechanism to turn on Systrace.

Most Linux-based systems and Apple Macintosh systems recognize Android devices using the standard Android SDK tools, without additional support; however Microsoft Windows systems typically require a driver for new Android devices. (For instance, new vendor IDs and sometimes new device IDs require custom USB drivers for Windows systems.) If a device implementation is unrecognized by the adb tool as provided in the standard Android SDK, device implementers MUST provide Windows drivers allowing developers to connect to the device using the adb protocol. These drivers MUST be provided for Windows XP, Windows Vista, Windows 7, Windows 8, and Windows 9 in both 32-bit and 64-bit versions.

6.2. Developer Options

Android includes support for developers to configure application development-related settings. Device implementations MUST honor the android.settings.APPLICATION_DEVELOPMENT_SETTINGS intent to show application development-related settings [ Resources, 60 ]. The upstream Android implementation hides the Developer Options menu by default and enables users to launch Developer Options after pressing seven (7) times on the Settings > About Device > Build Number menu item. Device implementations MUST provide a consistent experience for Developer Options. Specifically, device implementations MUST hide Developer Options by default and MUST provide a mechanism to enable Developer Options that is consistent with the upstream Android implementation.

7. Hardware Compatibility

If a device includes a particular hardware component that has a corresponding API for third-party developers, the device implementation MUST implement that API as described in the Android SDK documentation. If an API in the SDK interacts with a hardware component that is stated to be optional and the device implementation does not possess that component:

• Complete class definitions (as documented by the SDK) for the component APIs MUST still be presented.
• The API's behaviors MUST be implemented as no-ops in some reasonable fashion.
• API methods MUST return null values where permitted by the SDK documentation.
• API methods MUST return no-op implementations of classes where null values are not permitted by the SDK documentation.
• API methods MUST NOT throw exceptions not documented by the SDK documentation.

A typical example of a scenario where these requirements apply is the telephony API: even on non-phone devices, these APIs must be implemented as reasonable no-ops.

Device implementations MUST consistently report accurate hardware configuration information via the getSystemAvailableFeatures() and hasSystemFeature(String) methods on the android.content.pm.PackageManager class for the same build fingerprint. [ Resources, 53]

7.1. Display and Graphics

Android includes facilities that automatically adjust application assets and UI layouts appropriately for the device, to ensure that third-party applications run well on a variety of hardware configurations [ Resources, 61 ]. Devices MUST properly implement these APIs and behaviors, as detailed in this section.

The units referenced by the requirements in this section are defined as follows:

• physical diagonal size . The distance in inches between two opposing corners of the illuminated portion of the display.
• dots per inch (dpi) . The number of pixels encompassed by a linear horizontal or vertical span of 1”. Where dpi values are listed, both horizontal and vertical dpi must fall within the range.
• aspect ratio . The ratio of the pixels of the longer dimension to the shorter dimension of the screen. For example, a display of 480x854 pixels would be 854/480 = 1.779, or roughly “16:9”.
• density-independent pixel (dp) The virtual pixel unit normalized to a 160 dpi screen, calculated as: pixels = dps * (density/160).

7.1.1. Screen Configuration

7.1.1.1.螢幕尺寸

The Android UI framework supports a variety of different screen sizes, and allows applications to query the device screen size (aka “screen layout") via android.content.res.Configuration.screenLayout with the SCREENLAYOUT_SIZE_MASK. Device implementations MUST report the correct screen size as defined in the Android SDK documentation [ Resources, 61 ] and determined by the upstream Android platform. Specifically, device implementations MUST report the correct screen size according to the following logical density-independent pixel (dp) screen dimensions.

• Devices MUST have screen sizes of at least 426 dp x 320 dp ('small'), unless it is an Android Watch device.
• Devices that report screen size 'normal' MUST have screen sizes of at least 480 dp x 320 dp.
• Devices that report screen size 'large' MUST have screen sizes of at least 640 dp x 480 dp.
• Devices that report screen size 'xlarge' MUST have screen sizes of at least 960 dp x 720 dp.

此外，

• Android Watch devices MUST have a screen with the physical diagonal size in the range from 1.1 to 2.5 inches.
• Other types of Android device implementations, with a physically integrated screen, MUST have a screen at least 2.5 inches in physical diagonal size.

Devices MUST NOT change their reported screen size at any time.

Applications optionally indicate which screen sizes they support via the <supports-screens> attribute in the AndroidManifest.xml file. Device implementations MUST correctly honor applications' stated support for small, normal, large, and xlarge screens, as described in the Android SDK documentation.

7.1.1.2.螢幕縱橫比

The screen aspect ratio MUST be a value from 1.3333 (4:3) to 1.86 (roughly 16:9), but Android Watch devices MAY have an aspect ratio of 1.0 (1:1) because such a device implementation will use a UI_MODE_TYPE_WATCH as the android.content.res.Configuration.uiMode.

7.1.1.3。螢幕密度

The Android UI framework defines a set of standard logical densities to help application developers target application resources. Device implementations MUST report only one of the following logical Android framework densities through the android.util.DisplayMetrics APIs, and MUST execute applications at this standard density and MUST NOT change the value at at any time for the default display.

• 120 dpi (ldpi)
• 160 dpi (mdpi)
• 213 dpi (tvdpi)
• 240 dpi (hdpi)
• 280 dpi (280dpi)
• 320 dpi (xhdpi)
• 400 dpi (400dpi)
• 480 dpi (xxhdpi)
• 560 dpi (560dpi)
• 640 dpi (xxxhdpi)

Device implementations SHOULD define the standard Android framework density that is numerically closest to the physical density of the screen, unless that logical density pushes the reported screen size below the minimum supported. If the standard Android framework density that is numerically closest to the physical density results in a screen size that is smaller than the smallest supported compatible screen size (320 dp width), device implementations SHOULD report the next lowest standard Android framework density.

7.1.2. Display Metrics

Device implementations MUST report correct values for all display metrics defined in android.util.DisplayMetrics [ Resources, 62 ] and MUST report the same values regardless of whether the embedded or external screen is used as the default display.

7.1.3.螢幕方向

Devices MUST report which screen orientations they support (android.hardware.screen.portrait and/or android.hardware.screen.landscape) and MUST report at least one supported orientation. For example, a device with a fixed orientation landscape screen, such as a television or laptop, SHOULD only report android.hardware.screen.landscape.

Devices that report both screen orientations MUST support dynamic orientation by applications to either portrait or landscape screen orientation. That is, the device must respect the application's request for a specific screen orientation. Device implementations MAY select either portrait or landscape orientation as the default.

Devices MUST report the correct value for the device's current orientation, whenever queried via the android.content.res.Configuration.orientation, android.view.Display.getOrientation(), or other APIs.

Devices MUST NOT change the reported screen size or density when changing orientation.

7.1.4. 2D and 3D Graphics Acceleration

Device implementations MUST support both OpenGL ES 1.0 and 2.0, as embodied and detailed in the Android SDK documentations. Device implementations SHOULD support OpenGL ES 3.0 or 3.1 on devices capable of supporting it. Device implementations MUST also support Android RenderScript, as detailed in the Android SDK documentation [ Resources, 63 ].

Device implementations MUST also correctly identify themselves as supporting OpenGL ES 1.0, OpenGL ES 2.0, OpenGL ES 3.0 or OpenGL 3.1.那是：

• The managed APIs (such as via the GLES10.getString() method) MUST report support for OpenGL ES 1.0 and OpenGL ES 2.0.
• The native C/C++ OpenGL APIs (APIs available to apps via libGLES_v1CM.so, libGLES_v2.so, or libEGL.so) MUST report support for OpenGL ES 1.0 and OpenGL ES 2.0.
• Device implementations that declare support for OpenGL ES 3.0 or 3.1 MUST support the corresponding managed APIs and include support for native C/C++ APIs. On device implementations that declare support for OpenGL ES 3.0 or 3.1, libGLESv2.so MUST export the corresponding function symbols in addition to the OpenGL ES 2.0 function symbols.

In addition to OpenGL ES 3.1, Android provides an extension pack with Java interfaces [ Resources, 64 ] and native support for advanced graphics functionality such as tessellation and the ASTC texture compression format. Android device implementations MAY support this extension pack, and—only if fully implemented—MUST identify the support through the android.hardware.opengles.aep feature flag.

Also, device implementations MAY implement any desired OpenGL ES extensions. However, device implementations MUST report via the OpenGL ES managed and native APIs all extension strings that they do support, and conversely MUST NOT report extension strings that they do not support.

Note that Android includes support for applications to optionally specify that they require specific OpenGL texture compression formats. These formats are typically vendor-specific. Device implementations are not required by Android to implement any specific texture compression format. However, they SHOULD accurately report any texture compression formats that they do support, via the getString() method in the OpenGL API.

Android includes a mechanism for applications to declare that they want to enable hardware acceleration for 2D graphics at the Application, Activity, Window, or View level through the use of a manifest tag android:hardwareAccelerated or direct API calls [ Resources, 65 ].

Device implementations MUST enable hardware acceleration by default, and MUST disable hardware acceleration if the developer so requests by setting android:hardwareAccelerated="false” or disabling hardware acceleration directly through the Android View APIs.

In addition, device implementations MUST exhibit behavior consistent with the Android SDK documentation on hardware acceleration [ Resources, 65 ].

Android includes a TextureView object that lets developers directly integrate hardware-accelerated OpenGL ES textures as rendering targets in a UI hierarchy. Device implementations MUST support the TextureView API, and MUST exhibit consistent behavior with the upstream Android implementation.

Android includes support for EGL_ANDROID_RECORDABLE, an EGLConfig attribute that indicates whether the EGLConfig supports rendering to an ANativeWindow that records images to a video. Device implementations MUST support EGL_ANDROID_RECORDABLE extension [ Resources, 66 ].

7.1.5。 Legacy Application Compatibility Mode

Android specifies a “compatibility mode” in which the framework operates in a 'normal' screen size equivalent (320dp width) mode for the benefit of legacy applications not developed for old versions of Android that pre-date screen-size independence.

• Android Automotive does not support legacy compatibility mode.
• All other device implementations MUST include support for legacy application compatibility mode as implemented by the upstream Android open source code. That is, device implementations MUST NOT alter the triggers or thresholds at which compatibility mode is activated, and MUST NOT alter the behavior of the compatibility mode itself.

7.1.6。螢幕技術

The Android platform includes APIs that allow applications to render rich graphics to the display. Devices MUST support all of these APIs as defined by the Android SDK unless specifically allowed in this document.

• Devices MUST support displays capable of rendering 16-bit color graphics and SHOULD support displays capable of 24-bit color graphics.
• Devices MUST support displays capable of rendering animations.
• The display technology used MUST have a pixel aspect ratio (PAR) between 0.9 and 1.15. That is, the pixel aspect ratio MUST be near square (1.0) with a 10 ~ 15% tolerance.

7.1.7. Secondary Displays

Android includes support for secondary display to enable media sharing capabilities and developer APIs for accessing external displays. If a device supports an external display either via a wired, wireless, or an embedded additional display connection then the device implementation MUST implement the display manager API as described in the Android SDK documentation [ Resources, 67 ].

7.2.輸入裝置

Devices MUST support a touchscreen or meet the requirements listed in 7.2.2 for non-touch navigation.

7.2.1.鍵盤

設備實現：

• MUST include support for the Input Management Framework (which allows third-party developers to create Input Method Editors—ie soft keyboard) as detailed at http://developer.android.com .
• MUST provide at least one soft keyboard implementation (regardless of whether a hard keyboard is present) except for Android Watch devices where the screen size makes it less reasonable to have a soft keyboard.
• MAY include additional soft keyboard implementations.
• MAY include a hardware keyboard.
• MUST NOT include a hardware keyboard that does not match one of the formats specified in android.content.res.Configuration.keyboard [ Resources, 68 ] (QWERTY or 12-key).

7.2.2. Non-touch Navigation

設備實現：

• MAY omit a non-touch navigation option (trackball, d-pad, or wheel) if the device implementation is not an Android Television device.
• MUST report the correct value for android.content.res.Configuration.navigation [ Resources, 68 ].
• MUST provide a reasonable alternative user interface mechanism for the selection and editing of text, compatible with Input Management Engines. The upstream Android open source implementation includes a selection mechanism suitable for use with devices that lack non-touch navigation inputs.

7.2.3.導航鍵

The Home, Recents, and Back functions (mapped to the key events KEYCODE_HOME, KEYCODE_APP_SWITCH, KEYCODE_BACK, respectively) are essential to the Android navigation paradigm and therefore:

• Android Handheld device implementations MUST provide the Home, Recents, and Back functions.
• Android Television device implementations MUST provide the Home and Back functions.
• Android Watch device implementations MUST have the Home function available to the user, and the Back function except for when it is in UI_MODE_TYPE_WATCH.
• Android Automotive implementations MUST provide the Home function and MAY provide Back and Recent functions.
• All other types of device implementations MUST provide the Home and Back functions.

These functions MAY be implemented via dedicated physical buttons (such as mechanical or capacitive touch buttons), or MAY be implemented using dedicated software keys on a distinct portion of the screen, gestures, touch panel, etc. Android supports both implementations. All of these functions MUST be accessible with a single action (eg tap, double-click or gesture) when visible.

Recents function, if provided, MUST have a visible button or icon unless hidden together with other navigation functions in full-screen mode. This does not apply to devices upgrading from earlier Android versions that have physical buttons for navigation and no recents key.

The Home and Back functions, if provided, MUST each have a visible button or icon unless hidden together with other navigation functions in full-screen mode or when the uiMode UI_MODE_TYPE_MASK is set to UI_MODE_TYPE_WATCH.

The Menu function is deprecated in favor of action bar since Android 4.0. Therefore the new device implementations shipping with Android 5.0 and later MUST NOT implement a dedicated physical button for the Menu function. Older device implementations SHOULD NOT implement a dedicated physical button for the Menu function, but if the physical Menu button is implemented and the device is running applications with targetSdkVersion > 10, the device implementation:

• MUST display the action overflow button on the action bar when it is visible and the resulting action overflow menu popup is not empty. For a device implementation launched before Android 4.4 but upgrading to Android 5.1, this is RECOMMENDED.
• MUST NOT modify the position of the action overflow popup displayed by selecting the overflow button in the action bar.
• MAY render the action overflow popup at a modified position on the screen when it is displayed by selecting the physical menu button.

For backwards compatibility, device implementations MUST make the Menu function available to applications when targetSdkVersion is less than 10, either by a physical button, a software key, or gestures. This Menu function should be presented unless hidden together with other navigation functions.

Android supports Assist action [ Resources, 69 ]. Android device implementations except for Android Watch devices MUST make the Assist action available to the user at all times when running applications. The Assist action SHOULD be implemented as a long-press on the Home button or a swipe-up gesture on the software Home key. This function MAY be implemented via another physical button, software key, or gesture, but MUST be accessible with a single action (eg tap, double-click, or gesture) when other navigation keys are visible.

Device implementations MAY use a distinct portion of the screen to display the navigation keys, but if so, MUST meet these requirements:

• Device implementation navigation keys MUST use a distinct portion of the screen, not available to applications, and MUST NOT obscure or otherwise interfere with the portion of the screen available to applications.
• Device implementations MUST make available a portion of the display to applications that meets the requirements defined in section 7.1.1 .
• Device implementations MUST display the navigation keys when applications do not specify a system UI mode, or specify SYSTEM_UI_FLAG_VISIBLE.
• Device implementations MUST present the navigation keys in an unobtrusive “low profile” (eg. dimmed) mode when applications specify SYSTEM_UI_FLAG_LOW_PROFILE.
• Device implementations MUST hide the navigation keys when applications specify SYSTEM_UI_FLAG_HIDE_NAVIGATION.

7.2.4. Touchscreen Input

Device implementations SHOULD have a pointer input system of some kind (either mouse-like or touch). However, if a device implementation does not support a pointer input system, it MUST NOT report the android.hardware.touchscreen or android.hardware.faketouch feature constant. Device implementations that do include a pointer input system:

• SHOULD support fully independently tracked pointers, if the device input system supports multiple pointers.
• MUST report the value of android.content.res.Configuration.touchscreen [ Resources, 68 ] corresponding to the type of the specific touchscreen on the device.

Android includes support for a variety of touchscreens, touch pads, and fake touch input devices. Touchscreen based device implementations are associated with a display [ Resources, 70 ] such that the user has the impression of directly manipulating items on screen. Since the user is directly touching the screen, the system does not require any additional affordances to indicate the objects being manipulated. In contrast, a fake touch interface provides a user input system that approximates a subset of touchscreen capabilities. For example, a mouse or remote control that drives an on-screen cursor approximates touch, but requires the user to first point or focus then click. Numerous input devices like the mouse, trackpad, gyro-based air mouse, gyro-pointer, joystick, and multi-touch trackpad can support fake touch interactions. Android includes the feature constant android.hardware.faketouch, which corresponds to a high-fidelity non-touch (pointer-based) input device such as a mouse or trackpad that can adequately emulate touch-based input (including basic gesture support), and indicates that the device supports an emulated subset of touchscreen functionality. Device implementations that declare the fake touch feature MUST meet the fake touch requirements in section 7.2.5 .

Device implementations MUST report the correct feature corresponding to the type of input used. Device implementations that include a touchscreen (single-touch or better) MUST report the platform feature constant android.hardware.touchscreen. Device implementations that report the platform feature constant android.hardware.touchscreen MUST also report the platform feature constant android.hardware.faketouch. Device implementations that do not include a touchscreen (and rely on a pointer device only) MUST NOT report any touchscreen feature, and MUST report only android.hardware.faketouch if they meet the fake touch requirements in section 7.2.5 .

7.2.5. Fake Touch Input

Device implementations that declare support for android.hardware.faketouch:

• MUST report the absolute X and Y screen positions of the pointer location and display a visual pointer on the screen [ Resources, 71 ].
• MUST report touch event with the action code that specifies the state change that occurs on the pointer going down or up on the screen [ Resources, 71 ].
• MUST support pointer down and up on an object on the screen, which allows users to emulate tap on an object on the screen.
• MUST support pointer down, pointer up, pointer down then pointer up in the same place on an object on the screen within a time threshold, which allows users to emulate double tap on an object on the screen [ Resources, 71 ].
• MUST support pointer down on an arbitrary point on the screen, pointer move to any other arbitrary point on the screen, followed by a pointer up, which allows users to emulate a touch drag.
• MUST support pointer down then allow users to quickly move the object to a different position on the screen and then pointer up on the screen, which allows users to fling an object on the screen.

Devices that declare support for android.hardware.faketouch.multitouch.distinct MUST meet the requirements for faketouch above, and MUST also support distinct tracking of two or more independent pointer inputs.

7.2.6。 Game Controller Support

Android Television device implementations MUST support button mappings for game controllers as listed below. The upstream Android implementation includes implementation for game controllers that satisfies this requirement.

7.2.6.1. Button Mappings

Android Television device implementations MUST support the following key mappings:

1 [ Resources, 72 ]

2 The above HID usages must be declared within a Game pad CA (0x01 0x0005).

3 This usage must have a Logical Minimum of 0, a Logical Maximum of 7, a Physical Minimum of 0, a Physical Maximum of 315, Units in Degrees, and a Report Size of 4. The logical value is defined to be the clockwise rotation away from the vertical axis; for example, a logical value of 0 represents no rotation and the up button being pressed, while a logical value of 1 represents a rotation of 45 degrees and both the up and left keys being pressed.

4 [ Resources, 71 ]

1 [ Resources, 71 ]

7.2.7.遙控

Android Television device implementations SHOULD provide a remote control to allow users to access the TV interface. The remote control MAY be a physical remote or can be a software-based remote that is accessible from a mobile phone or tablet. The remote control MUST meet the requirements defined below.

• Search affordance . Device implementations MUST fire KEYCODE_SEARCH when the user invokes voice search either on the physical or software-based remote.
• 導航。 All Android Television remotes MUST include Back, Home, and Select buttons and support for D-pad events [ Resources, 72 ].

7.3.感應器

Android includes APIs for accessing a variety of sensor types. Devices implementations generally MAY omit these sensors, as provided for in the following subsections. If a device includes a particular sensor type that has a corresponding API for third-party developers, the device implementation MUST implement that API as described in the Android SDK documentation and the Android Open Source documentation on sensors [ Resources, 73 ]. For example, device implementations:

• MUST accurately report the presence or absence of sensors per the android.content.pm.PackageManager class [ Resources, 53] .
• MUST return an accurate list of supported sensors via the SensorManager.getSensorList() and similar methods.
• MUST behave reasonably for all other sensor APIs (for example, by returning true or false as appropriate when applications attempt to register listeners, not calling sensor listeners when the corresponding sensors are not present; etc.).
• MUST report all sensor measurements using the relevant International System of Units (metric) values for each sensor type as defined in the Android SDK documentation [ Resources, 74 ].
• SHOULD report the event time in nanoseconds as defined in the Android SDK documentation, representing the time the event happened and synchronized with the SystemClock.elapsedRealtimeNano() clock. Existing and new Android devices are very strongly encouraged to meet these requirement so they will be able to upgrade to the future platform releases where this might become a REQUIRED component. The synchronization error SHOULD be below 100 milliseconds [ Resources, 75 ].

The list above is not comprehensive; the documented behavior of the Android SDK and the Android Open Source Documentations on Sensors [ Resources, 73 ] is to be considered authoritative.

Some sensor types are composite, meaning they can be derived from data provided by one or more other sensors. (Examples include the orientation sensor, and the linear acceleration sensor.) Device implementations SHOULD implement these sensor types, when they include the prerequisite physical sensors as described in [ Resources, 76 ]. If a device implementation includes a composite sensor it MUST implement the sensor as described in the Android Open Source documentation on composite sensors [ Resources, 76 ].

Some Android sensors support a “continuous” trigger mode, which returns data continuously [ Resources, 77 ].為 any API indicated by the Android SDK documentation to be a continuous sensor, device implementations MUST continuously provide periodic data samples that SHOULD have a jitter below 3%, where jitter is definal reportas the stand valviues swue valviues value.事件。

Note that the device implementations MUST ensure that the sensor event stream MUST NOT prevent the device CPU from entering a suspend state or waking up from a suspend state.

Finally, when several sensors are activated, the power consumption SHOULD NOT exceed the sum of the individual sensor's reported power consumption.

7.3.1.加速度計

Device implementations SHOULD include a 3-axis accelerometer. Android Handheld devices and Android Watch devices are strongly encouraged to include this sensor. If a device implementation does include a 3-axis accelerometer, it:

• MUST implement and report TYPE_ACCELEROMETER sensor [ Resources, 78 ].
• MUST be able to report events up to a frequency of at least 50 Hz for Android Watch devices as such devices have a stricter power constraint and 100 Hz for all other device types.
• SHOULD report events up to at least 200 Hz.
• MUST comply with the Android sensor coordinate system as detailed in the Android APIs [ Resources, 74 ].
• MUST be capable of measuring from freefall up to four times the gravity (4g) or more on any axis.
• MUST have a resolution of at least 8-bits and SHOULD have a resolution of at least 16-bits.
• SHOULD be calibrated while in use if the characteristics changes over the life cycle and compensated, and preserve the compensation parameters between device reboots.
• SHOULD be temperature compensated.
• MUST have a standard deviation no greater than 0.05 m/s^, where the standard deviation should be calculated on a per axis basis on samples collected over a period of at least 3 seconds at the fastest sampling rate.
• SHOULD implement the TYPE_SIGNIFICANT_MOTION, TYPE_TILT_DETECTOR, TYPE_STEP_DETECTOR, TYPE_STEP_COUNTER composite sensors as described in the Android SDK document. Existing and new Android devices are very strongly encouraged to implement the TYPE_SIGNIFICANT_MOTION composite sensor. If any of these sensors are implemented, the sum of their power consumption MUST always be less than 4 mW and SHOULD each be below 2 mW and 0.5 mW for when the device is in a dynamic or static condition.
• If a gyroscope sensor is included, MUST implement the TYPE_GRAVITY and TYPE_LINEAR_ACCELERATION composite sensors and SHOULD implement the TYPE_GAME_ROTATION_VECTOR composite sensor. Existing and new Android devices are strongly encouraged to implement the TYPE_GAME_ROTATION_VECTOR sensor.
• SHOULD implement a TYPE_ROTATION_VECTOR composite sensor, if a gyroscope sensor and a magnetometer sensor is also included.

7.3.2.磁力計

Device implementations SHOULD include a 3-axis magnetometer (compass). If a device does include a 3-axis magnetometer, it:

• MUST implement the TYPE_MAGNETIC_FIELD sensor and SHOULD also implement TYPE_MAGNETIC_FIELD_UNCALIBRATED sensor. Existing and new Android devices are strongly encouraged to implement the TYPE_MAGNETIC_FIELD_UNCALIBRATED sensor.
• MUST be able to report events up to a frequency of at least 10 Hz and SHOULD report events up to at least 50 Hz.
• MUST comply with the Android sensor coordinate system as detailed in the Android APIs [ Resources, 74 ].
• MUST be capable of measuring between -900 µT and +900 µT on each axis before saturating.
• MUST have a hard iron offset value less than 700 µT and SHOULD have a value below 200 µT, by placing the magnetometer far from dynamic (current-induced) and static (magnet-induced) magnetic fields.
• MUST have a resolution equal or denser than 0.6 µT and SHOULD have a resolution equal or denser than 0.2 µ.
• SHOULD be temperature compensated.
• MUST support online calibration and compensation of the hard iron bias, and preserve the compensation parameters between device reboots.
• MUST have the soft iron compensation applied—the calibration can be done either while in use or during the production of the device.
• SHOULD have a standard deviation, calculated on a per axis basis on samples collected over a period of at least 3 seconds at the fastest sampling rate, no greater than 0.5 µT.
• SHOULD implement a TYPE_ROTATION_VECTOR composite sensor, if an accelerometer sensor and a gyroscope sensor is also included.
• MAY implement the TYPE_GEOMAGNETIC_ROTATION_VECTOR sensor if an accelerometer sensor is also implemented. However if implemented, it MUST consume less than 10 mW and SHOULD consume less than 3 mW when the sensor is registered for batch mode at 10 Hz.

7.3.3.全球定位系統

Device implementations SHOULD include a GPS receiver. If a device implementation does include a GPS receiver, it SHOULD include some form of“assisted GPS” technique to minimize GPS lock-on time.

7.3.4.陀螺儀

Device implementations SHOULD include a gyroscope (angular change sensor). Devices SHOULD NOT include a gyroscope sensor unless a 3-axis accelerometer is also included. If a device implementation includes a gyroscope, it:

• MUST implement the TYPE_GYROSCOPE sensor and SHOULD also implement TYPE_GYROSCOPE_UNCALIBRATED sensor. Existing and new Android devices are strongly encouraged to implement the SENSOR_TYPE_GYROSCOPE_UNCALIBRATED sensor.
• MUST be capable of measuring orientation changes up to 1,000 degrees per second.
• MUST be able to report events up to a frequency of at least 50 Hz for Android Watch devices as such devices have a stricter power constraint and 100 Hz for all other device types.
• SHOULD report events up to at least 200 Hz.
• MUST have a resolution of 12-bits or more and SHOULD have a resolution of 16-bits or more.
• MUST be temperature compensated.
• MUST be calibrated and compensated while in use, and preserve the compensation parameters between device reboots.
• MUST have a variance no greater than 1e-7 rad^2 / s^2 per Hz (variance per Hz, or rad^2 / s). The variance is allowed to vary with the sampling rate, but must be constrained by this value. In other words, if you measure the variance of the gyro at 1 Hz sampling rate it should be no greater than 1e-7 rad^2/s^2.
• SHOULD implement a TYPE_ROTATION_VECTOR composite sensor, if an accelerometer sensor and a magnetometer sensor is also included.
• If an accelerometer sensor is included, MUST implement the TYPE_GRAVITY and TYPE_LINEAR_ACCELERATION composite sensors and SHOULD implement the TYPE_GAME_ROTATION_VECTOR composite sensor. Existing and new Android devices are strongly encouraged to implement the TYPE_GAME_ROTATION_VECTOR sensor.

7.3.5.晴雨表

Device implementations SHOULD include a barometer (ambient air pressure sensor). If a device implementation includes a barometer, it:

• MUST implement and report TYPE_PRESSURE sensor.
• MUST be able to deliver events at 5 Hz or greater.
• MUST have adequate precision to enable estimating altitude.
• MUST be temperature compensated.

7.3.6。溫度計

Device implementations MAY include an ambient thermometer (temperature sensor). If present, it MUST be defined as SENSOR_TYPE_AMBIENT_TEMPERATURE and it MUST measure the ambient (room) temperature in degrees Celsius.

Device implementations MAY but SHOULD NOT include a CPU temperature sensor. If present, it MUST be defined as SENSOR_TYPE_TEMPERATURE, it MUST measure the temperature of the device CPU, and it MUST NOT measure any other temperature. Note the SENSOR_TYPE_TEMPERATURE sensor type was deprecated in Android 4.0.

7.3.7.光度計

Device implementations MAY include a photometer (ambient light sensor).

7.3.8.接近感測器

Device implementations MAY include a proximity sensor. Devices that can make a voice call and indicate any value other than PHONE_TYPE_NONE in getPhoneType SHOULD include a proximity sensor. If a device implementation does include a proximity sensor, it:

• MUST measure the proximity of an object in the same direction as the screen. That is, the proximity sensor MUST be oriented to detect objects close to the screen, as the primary intent of this sensor type is to detect a phone in use by the user. If a device implementation includes a proximity sensor with any other orientation, it MUST NOT be accessible through this API.
• MUST have 1-bit of accuracy or more.

7.4.數據連接

7.4.1.電話

“Telephony” as used by the Android APIs and this document refers specifically to hardware related to placing voice calls and sending SMS messages via a GSM or CDMA network. While these voice calls may or may not be packet-switched, they are for the purposes of Android considered independent of any data connectivity that may be implemented using the same network. In other words, the Android “telephony” functionality and APIs refer specifically to voice calls and SMS. For instance, device implementations that cannot place calls or send/receive SMS messages MUST NOT report the android.hardware.telephony feature or any subfeatures, regardless of whether they use a cellular network for data connectivity.

Android MAY be used on devices that do not include telephony hardware. That is, Android is compatible with devices that are not phones. However, if a device implementation does include GSM or CDMA telephony, it MUST implement full support for the API for that technology. Device implementations that do not include telephony hardware MUST implement the full APIs as no-ops.

7.4.2. IEEE 802.11 (Wi-Fi)

Android Television device implementations MUST include support for one or more forms of 802.11 (b/g/a/n, etc.) and other types of Android device implementation SHOULD include support for one or more forms of 802.11. If a device implementation does include support for 802.11 and exposes the functionality to a third-party application, it MUST implement the corresponding Android API and:

• MUST report the hardware feature flag android.hardware.wifi.
• MUST implement the multicast API as described in the SDK documentation [ Resources, 79 ].
• MUST support multicast DNS (mDNS) and MUST NOT filter mDNS packets (224.0.0.251) at any time of operation including when the screen is not in an active state.

7.4.2.1.無線直連

Device implementations SHOULD include support for Wi-Fi Direct (Wi-Fi peer-to-peer). If a device implementation does include support for Wi-Fi Direct, it MUST implement the corresponding Android API as described in the SDK documentation [ Resources, 80 ]. If a device implementation includes support for Wi-Fi Direct, then it:

• MUST report the hardware feature android.hardware.wifi.direct.
• MUST support regular Wi-Fi operation.
• SHOULD support concurrent Wi-Fi and Wi-Fi Direct operation.

7.4.2.2. Wi-Fi Tunneled Direct Link Setup

Android Television device implementations MUST include support for Wi-Fi Tunneled Direct Link Setup (TDLS) and other types of Android device implementations SHOULD include support for Wi-Fi TDLS as described in the Android SDK Documentation [ Resources, 81 ]. If a device implementation does include support for TDLS and TDLS is enabled by the WiFiManager API, the device:

• SHOULD use TDLS only when it is possible AND beneficial.
• SHOULD have some heuristic and NOT use TDLS when its performance might be worse than going through the Wi-Fi access point.

7.4.3.藍牙

Android includes support for Bluetooth and Bluetooth Low Energy [ Resources, 82 ]. Device implementations that include support for Bluetooth and Bluetooth Low Energy MUST declare the relevant platform features (android.hardware.bluetooth and android.hardware.bluetooth_le respectively) and implement the platform APIs. Device implementations SHOULD implement relevant Bluetooth profiles such as A2DP, AVCP, OBEX, etc. as appropriate for the device. Android Television device implementations MUST support Bluetooth and Bluetooth LE.

Device implementations including support for Bluetooth Low Energy:

• MUST declare the hardware feature android.hardware.bluetooth_le.
• MUST enable the GATT (generic attribute profile) based Bluetooth APIs as described in the SDK documentation and [ Resources, 82 ].
• SHOULD support offloading of the filtering logic to the bluetooth chipset when implementing the ScanFilter API [ Resources, 83 ], and MUST report the correct value of where the filtering logic is implemented whenever queried via the android.bluetooth.BluetoothAdapter.isOffloadedFilteringSupported() method.
• SHOULD support offloading of the batched scanning to the bluetooth chipset, but if not supported, MUST report 'false' whenever queried via the android.bluetooth.BluetoothAdapater.isOffloadedScanBatchingSupported() method.
• SHOULD support multi advertisement with at least 4 slots, but if not supported, MUST report 'false' whenever queried via the android.bluetooth.BluetoothAdapter.isMultipleAdvertisementSupported() method.

7.4.4. Near-Field Communications

Device implementations SHOULD include a transceiver and related hardware for Near-Field Communications (NFC). If a device implementation does include NFC hardware and plans to make it available to third-party apps, then it:

• MUST report the android.hardware.nfc feature from the android.content.pm.PackageManager.hasSystemFeature() method [ Resources, 53 ].
• MUST be capable of reading and writing NDEF messages via the following NFC standards:
  • MUST be capable of acting as an NFC Forum reader/writer (as defined by the NFC Forum technical specification NFCForum-TS-DigitalProtocol-1.0) via the following NFC standards:
    • NfcA (ISO14443-3A)
    • NfcB (ISO14443-3B)
    • NfcF (JIS 6319-4)
    • IsoDep (ISO 14443-4)
    • NFC Forum Tag Types 1, 2, 3, 4 (defined by the NFC Forum)
  • SHOULD be capable of reading and writing NDEF messages via the following NFC standards. Note that while the NFC standards below are stated as SHOULD, the Compatibility Definition for a future version is planned to change these to MUST. These standards are optional in this version but will be required in future versions. Existing and new devices that run this version of Android are very strongly encouraged to meet these requirements now so they will be able to upgrade to the future platform releases.
  • NfcV (ISO 15693)
  • MUST be capable of transmitting and receiving data via the following peer-to-peer standards and protocols:
    • ISO 18092
    • LLCP 1.0 (defined by the NFC Forum)
    • SDP 1.0 (defined by the NFC Forum)
    • NDEF Push Protocol [ Resources, 84 ]
    • SNEP 1.0 (defined by the NFC Forum)
  • MUST include support for Android Beam [ Resources, 85 ]:
    • MUST implement the SNEP default server. Valid NDEF messages received by the default SNEP server MUST be dispatched to applications using the android.nfc.ACTION_NDEF_DISCOVERED intent. Disabling Android Beam in settings MUST NOT disable dispatch of incoming NDEF message.
    • MUST honor the android.settings.NFCSHARING_SETTINGS intent to show NFC sharing settings [ Resources, 86 ].
    • MUST implement the NPP server. Messages received by the NPP server MUST be processed the same way as the SNEP default server.
    • MUST implement a SNEP client and attempt to send outbound P2P NDEF to the default SNEP server when Android Beam is enabled. If no default SNEP server is found then the client MUST attempt to send to an NPP server.
    • MUST allow foreground activities to set the outbound P2P NDEF message using android.nfc.NfcAdapter.setNdefPushMessage, and android.nfc.NfcAdapter.setNdefPushMessageCallback, and android.nfc.NfcAdapter.enableForegroundNdefPush.
    • SHOULD use a gesture or on-screen confirmation, such as 'Touch to Beam', before sending outbound P2P NDEF messages.
    • SHOULD enable Android Beam by default and MUST be able to send and receive using Android Beam, even when another proprietary NFC P2p mode is turned on.
    • MUST support NFC Connection handover to Bluetooth when the device supports Bluetooth Object Push Profile. Device implementations MUST support connection handover to Bluetooth when using android.nfc.NfcAdapter.setBeamPushUris, by implementing the “Connection Handover version 1.2” [ Resources, 87 ] and “Bluetooth Secure Simple Pairing Uure NFC. NFC 論壇。 Such an implementation MUST implement the handover LLCP service with service name “urn:nfc:sn:handover” for exchanging the handover request/select records over NFC, and it MUST use the Bluetooth Object Push Profile for the actual Bluetooth data transfer. For legacy reasons (to remain compatible with Android 4.1 devices), the implementation SHOULD still accept SNEP GET requests for exchanging the handover request/select records over NFC. However an implementation itself SHOULD NOT send SNEP GET requests for performing connection handover.
  • MUST poll for all supported technologies while in NFC discovery mode.
  • SHOULD be in NFC discovery mode while the device is awake with the screen active and the lock-screen unlocked.

(Note that publicly available links are not available for the JIS, ISO, and NFC Forum specifications cited above.)

Android includes support for NFC Host Card Emulation (HCE) mode. If a device implementation does include an NFC controller chipset capable of HCE and Application ID (AID) routing, then it:

• MUST report the android.hardware.nfc.hce feature constant.
• MUST support NFC HCE APIs as defined in the Android SDK [ Resources, 10 ].

Additionally, device implementations MAY include reader/writer support for the following MIFARE technologies.

• MIFARE 經典版
• MIFARE Ultralight
• NDEF on MIFARE Classic

Note that Android includes APIs for these MIFARE types. If a device implementation supports MIFARE in the reader/writer role, it:

• MUST implement the corresponding Android APIs as documented by the Android SDK.
• MUST report the feature com.nxp.mifare from the android.content.pm.PackageManager.hasSystemFeature() meth od [Resources, 53] . Note that this is not a standard Android feature and as such does not appear as a constant on the PackageManager class.
• MUST NOT implement the corresponding Android APIs nor report the com.nxp.mifare feature unless it also implements general NFC support as described in this section.

If a device implementation does not include NFC hardware, it MUST NOT declare the android.hardware.nfc feature from the android.content.pm.PackageManager.hasSystemFeature() method [ Resources, 53] , and MUST implement the Android NFC API as a no-op.

As the classes android.nfc.NdefMessage and android.nfc.NdefRecord represent a protocol-independent data representation format, device implementations MUST implement these APIs even if they do not include support for NFC or declare the android.hardware.nfc feature.

7.4.5。 Minimum Network Capability

Device implementations MUST include support for one or more forms of data networking. Specifically, device implementations MUST include support for at least one data standard capable of 200Kbit/sec or greater. Examples of technologies that satisfy this requirement include EDGE, HSPA, EV-DO, 802.11g, Ethernet, Bluetooth PAN, etc.

Device implementations where a physical networking standard (such as Ethernet) is the primary data connection SHOULD also include support for at least one common wireless data standard, such as 802.11 (Wi-Fi).

Devices MAY implement more than one form of data connectivity.

7.4.6。同步設定

Device implementations MUST have the master auto-sync setting on by default so that the method getMasterSyncAutomatically() returns “true” [ Resources, 89 ].

7.5。相機

Device implementations SHOULD include a rear-facing camera and MAY include a front-facing camera. A rear-facing camera is a camera located on the side of the device opposite the display; that is, it images scenes on the far side of the device, like a traditional camera. A front-facing camera is a camera located on the same side of the device as the display; that is, a camera typically used to image the user, such as for video conferencing and similar applications.

If a device implementation includes at least one camera, it SHOULD be possible for an application to simultaneously allocate 3 bitmaps equal to the size of the images produced by the largest-resolution camera sensor on the device.

7.5.1. Rear-Facing Camera

Device implementations SHOULD include a rear-facing camera. If a device implementation includes at least one rear-facing camera, it:

• MUST report the feature flag android.hardware.camera and android.hardware.camera.any.
• MUST have a resolution of at least 2 megapixels.
• SHOULD have either hardware auto-focus or software auto-focus implemented in the camera driver (transparent to application software).
• MAY have fixed-focus or EDOF (extended depth of field) hardware.
• MAY include a flash. If the Camera includes a flash, the flash lamp MUST NOT be lit while an android.hardware.Camera.PreviewCallback instance has been registered on a Camera preview surface, unless the application has explicitly enabled the flash by enabling the FLASH_MODE_AUTO or FLASH_MODE_ON attributes of a Camera.Parameters object. Note that this constraint does not apply to the device's built-in system camera application, but only to third-party applications using Camera.PreviewCallback.

7.5.2. Front-Facing Camera

Device implementations MAY include a front-facing camera. If a device implementation includes at least one front-facing camera, it:

• MUST report the feature flag android.hardware.camera.any and android.hardware.camera.front.
• MUST have a resolution of at least VGA (640x480 pixels).
• MUST NOT use a front-facing camera as the default for the Camera API. The camera API in Android has specific support for front-facing cameras and device implementations MUST NOT configure the API to to treat a front-facing camera as the default rear-facing camera, even if it is the only camera on the device.
• MAY include features (such as auto-focus, flash, etc.) available to rear-facing cameras as described in section 7.5.1 .
• MUST horizontally reflect (ie mirror) the stream displayed by an app in a CameraPreview, as follows:
  • If the device implementation is capable of being rotated by user (such as automatically via an accelerometer or manually via user input), the camera preview MUST be mirrored horizontally relative to the device's current orientation.
  • If the current application has explicitly requested that the Camera display be rotated via a call to the android.hardware.Camera.setDisplayOrientation()[ Resources, 90 ] method, the camera preview MUST be mirrored horizontally relative to the orientation specified by the application.
  • Otherwise, the preview MUST be mirrored along the device's default horizontal axis.
• MUST mirror the image displayed by the postview in the same manner as the camera preview image stream. If the device implementation does not support postview, this requirement obviously does not apply.
• MUST NOT mirror the final captured still image or video streams returned to application callbacks or committed to media storage.

7.5.3.外接攝影機

Device implementations with USB host mode MAY include support for an external camera that connects to the USB port. If a device includes support for an external camera, it:

• MUST declare the platform feature android.hardware.camera.external and android.hardware camera.any.
• MUST support USB Video Class (UVC 1.0 or higher).
• MAY support multiple cameras.

Video compression (such as MJPEG) support is RECOMMENDED to enable transfer of high-quality unencoded streams (ie raw or independently compressed picture streams). Camera-based video encoding MAY be supported. If so, a simultaneous unencoded/ MJPEG stream (QVGA or greater resolution) MUST be accessible to the device implementation.

7.5.4. Camera API Behavior

Android includes two API packages to access the camera, the newer android.hardware.camera2 API expose lower-level camera control to the app, including efficient zero-copy burst/streaming flows and per-frame controls of exposure, gain, white balance gains, color conversion, denoising, sharpening, and more.

The older API package, android.hardware.Camera, is marked as deprecated in Android 5.0 but as it should still be available for apps to use Android device implementations MUST ensure the continued support of the API as descred in this as thiss in the 。

Device implementations MUST implement the following behaviors for the camera-related APIs, for all available cameras:

• If an application has never called android.hardware.Camera.Parameters.setPreviewFormat(int), then the device MUST use android.hardware.PixelFormat.YCbCr_420_SP for preview data provided to application callbacks.
• If an application registers an android.hardware.Camera.PreviewCallback instance and the system calls the onPreviewFrame() method when the preview format is YCbCr_420_SP, the data in the byte[] passed into onPreviewFrame() must further be in the NV21 encoding format. That is, NV21 MUST be the default.
• For android.hardware.Camera, device implementations MUST support the YV12 format (as denoted by the android.graphics.ImageFormat.YV12 constant) for camera previews for both front- and rear-facing cameras. (The hardware video encoder and camera may use any native pixel format, but the device implementation MUST support conversion to YV12.)
• For android.hardware.camera2, device implementations must support the android.hardware.ImageFormat.YUV_420_888 and android.hardware.ImageFormat.JPEG formats as outputs through the android.media.ImageReader API.

Device implementations MUST still implement the full Camera API included in the Android SDK documentation [ Resources, 91 ], regardless of whether the device includes hardware autofocus or other capabilities. For instance, cameras that lack autofocus MUST still call any registered android.hardware.Camera.AutoFocusCallback instances (even though this has no relevance to a non-autofocus camera.) Note that this does apply to front-facing cameras; for instance, even though most front-facing cameras do not support autofocus, the API callbacks must still be “faked” as described.

Device implementations MUST recognize and honor each parameter name defined as a constant on the android.hardware.Camera.Parameters class, if the underlying hardware supports the feature. If the device hardware does not support a feature, the API must behave as documented. Conversely, device implementations MUST NOT honor or recognize string constants passed to the android.hardware.Camera.setParameters() method other than those documented as constants on the android.hardware.Camera.Parameters. That is, device implementations MUST support all standard Camera parameters if the hardware allows, and MUST NOT support custom Camera parameter types. For instance, device implementations that support image capture using high dynamic range (HDR) imaging techniques MUST support camera parameter Camera.SCENE_MODE_HDR [ Resources, 92 ].

Because not all device implementations can fully support all the features of the android.hardware.camera2 API, device implementations MUST report the proper level of support with the android.info.supportedHardwareLevel property as described in the Android SDK [ Resources, 93] and report the appropriate framework feature flags [ Resources, 94] .

Device implementations MUST also declare its Individual camera capabilities of android.hardware.camera2 via the android.request.availableCapabilities property and declare the appropriate feature flags [ Resources, 94] ; a device must define the feature flag if any of its attached camera devices supports the feature.

Device implementations MUST broadcast the Camera.ACTION_NEW_PICTURE intent whenever a new picture is taken by the camera and the entry of the picture has been added to the media store.

Device implementations MUST broadcast the Camera.ACTION_NEW_VIDEO intent whenever a new video is recorded by the camera and the entry of the picture has been added to the media store.

7.5.5。 Camera Orientation

Both front- and rear-facing cameras, if present, MUST be oriented so that the long dimension of the camera aligns with the screen's long dimension. That is, when the device is held in the landscape orientation, cameras MUST capture images in the landscape orientation. This applies regardless of the device's natural orientation; that is, it applies to landscape-primary devices as well as portrait-primary devices.

7.6。記憶體和儲存

7.6.1. Minimum Memory and Storage

The memory available to the kernel and userspace on device implementations MUST be at least equal or larger than the minimum values specified by the following table. (See section 7.1.1 for screen size and density definitions.)

The minimum memory values MUST be in addition to any memory space already dedicated to hardware components such as radio, video, and so on that is not under the kernel's control.

Device implementations with less than 512MB of memory available to the kernel and userspace, unless an Android Watch, MUST return the value "true" for ActivityManager.isLowRamDevice().

Android Television devices MUST have at least 5GB and other device implementations MUST have at least 1.5GB of non-volatile storage available for application private data. That is, the /data partition MUST be at least 5GB for Android Television devices and at least 1.5GB for other device implementations. Device implementations that run Android are very strongly encouraged to have at least 3GB of non-volatile storage for application private data so they will be able to upgrade to the future platform releases.

The Android APIs include a Download Manager that applications MAY use to download data files [ Resources, 95 ]. The device implementation of the Download Manager MUST be capable of downloading individual files of at least 100MB in size to the default “cache" location.

7.6.2. Application Shared Storage

Device implementations MUST offer shared storage for applications also often referred as “shared external storage”.

Device implementations MUST be configured with shared storage mounted by default, “out of the box”. If the shared storage is not mounted on the Linux path /sdcard, then the device MUST include a Linux symbolic link from /sdcard to the actual mount point.

Device implementations MAY have hardware for user-accessible removable storage, such as a Secure Digital (SD) card slot. If this slot is used to satisfy the shared storage requirement, the device implementation:

• MUST implement a toast or pop-up user interface warning the user when there is no SD card.
• MUST include a FAT-formatted SD card 1GB in size or larger OR show on the box and other material available at time of purchase that the SD card has to be separately purchased.
• MUST mount the SD card by default.

Alternatively, device implementations MAY allocate internal (non-removable) storage as shared storage for apps as included in the upstream Android Open Source Project; device implementations SHOULD use this configuration and software implementation. If a device implementation uses internal (non-removable) storage to satisfy the shared storage requirement, while that storage MAY share space with the application private data, it MUST be at least 1GB in size and mounted on /sdcard (or /sdcard MUST be a symbolic link to the physical location if it is mounted elsewhere).

Device implementations MUST enforce as documented the android.permission.WRITE_EXTERNAL_STORAGE permission on this shared storage. Shared storage MUST otherwise be writable by any application that obtains that permission.

Device implementations that include multiple shared storage paths (such as both an SD card slot and shared internal storage) MUST allow only pre-installed and privileged Android applications with the WRITE_EXTERNAL_STORAGE permission to write to the secondary external storage, except when writing to their package-specific directories or within the URI returned by firing the ACTION_OPEN_DOCUMENT_TREE intent.

However, device implementations SHOULD expose content from both storage paths transparently through Android's media scanner service and android.provider.MediaStore.

Regardless of the form of shared storage used, if the device implementation has a USB port with USB peripheral mode support, it MUST provide some mechanism to access the contents of shared storage from a host computer. Device implementations MAY use USB mass storage, but SHOULD use Media Transfer Protocol to satisfy this requirement. If the device implementation supports Media Transfer Protocol, it:

• SHOULD be compatible with the reference Android MTP host, Android File Transfer [ Resources, 96 ].
• SHOULD report a USB device class of 0x00.
• SHOULD report a USB interface name of 'MTP'.

7.7. USB

Device implementations SHOULD support USB peripheral mode and SHOULD support USB host mode.

If a device implementation includes a USB port supporting peripheral mode:

• The port MUST be connectable to a USB host that has a standard type-A or type -C USB port.
• The port SHOULD use micro-B, micro-AB or Type-C USB form factor. Existing and new Android devices are STRONGLY RECOMMENDED to meet these requirements so they will be able to upgrade to future platform releases.
• The port SHOULD either be located on the bottom of the device (according to natural orientation) or enable software screen rotation for all apps (including home screen), so that the display draws correctly when the device is oriented with the port at bottom. Existing and new Android devices are STRONGLY RECOMMENDED to meet these requirements so they will be able to upgrade to future platform releases.
• It SHOULD implement the Android Open Accessory (AOA) API and specification as documented in the Android SDK documentation, and if it is an Android Handheld device it MUST implement the AOA API. Device implementations implementing the AOA specification:
  • MUST declare support for the hardware feature android.hardware.usb.accessory [ Resources, 97 ].
  • MUST implement the USB audio class as documented in the Android SDK documentation [ Resources, 98 ].
• It SHOULD implement support to draw 1.5 A current during HS chirp and traffic as specified in the USB Battery Charging Specification, Revision 1.2 [ Resources, 99 ]. Existing and new Android devices are STRONGLY RECOMMENDED to meet these requirements so they will be able to upgrade to the future platform releases.
• The value of iSerialNumber in USB standard device descriptor MUST be equal to the value of android.os.Build.SERIAL.

If a device implementation includes a USB port supporting host mode, it:

• SHOULD use a type-C USB port, if the device implementation supports USB 3.1.
• MAY use a non-standard port form factor, but if so MUST ship with a cable or cables adapting the port to a standard type-A or type-C USB port.
• MAY use a micro-AB USB port, but if so SHOULD ship with a cable or cables adapting the port to a standard type-A or type-C USB port.
• is very strongly RECOMMENDED to implement the USB audio class as documented in the Android SDK documentation [ Resources, 98 ].
• MUST implement the Android USB host API as documented in the Android SDK, and MUST declare support for the hardware feature android.hardware.usb.host [ Resources, 100 ].
• SHOULD support the Charging Downstream Port output current range of 1.5 A ~ 5 A as specified in the USB Battery Charging Specification, Revision 1.2 [ Resources, 99 ].

7.8。聲音的

7.8.1.麥克風

Device implementations MAY omit a microphone. However, if a device implementation omits a microphone, it MUST NOT report the android.hardware.microphone feature constant, and MUST implement the audio recording API at least as no-ops, per section 7 . Conversely, device implementations that do possess a microphone:

• MUST report the android.hardware.microphone feature constant
• MUST meet the audio recording requirements in section 5.4
• MUST meet the audio latency requirements in section 5.6

7.8.2.音訊輸出

Device implementations including a speaker or with an audio/multimedia output port for an audio output peripheral as a headset or an external speaker:

• MUST report the android.hardware.audio.output feature constant.
• MUST meet the audio playback requirements in section 5.5 .
• MUST meet the audio latency requirements in section 5.6 .

Conversely, if a device implementation does not include a speaker or audio output port, it MUST NOT report the android.hardware.audio output feature, and MUST implement the Audio Output related APIs as no-ops at least.

Android Watch device implementation MAY but SHOULD NOT have audio output, but other types of Android device implementations MUST have an audio output and declare android.hardware.audio.output.

7.8.2.1. Analog Audio Ports

In order to be compatible with the headsets and other audio accessories using the 3.5mm audio plug across the Android ecosystem [ Resources, 101 ], if a device implementation includes one or more analog audio ports, at least one of the audio port(s) SHOULD be a 4 conductor 3.5mm audio jack. If a device implementation has a 4 conductor 3.5mm audio jack, it:

• MUST support audio playback to stereo headphones and stereo headsets with a microphone, and SHOULD support audio recording from stereo headsets with a microphone.
• MUST support TRRS audio plugs with the CTIA pin-out order, and SHOULD support audio plugs with the OMTP pin-out order.
• MUST support the detection of microphone on the plugged in audio accessory, if the device implementation supports a microphone, and broadcast the android.intent.action.HEADSET_PLUG with the extra value microphone set as 1.
• SHOULD support the detection and mapping to the keycodes for the following 3 ranges of equivalent impedance between the microphone and ground conductors on the audio plug:
  • 70 ohm or less : KEYCODE_HEADSETHOOK
  • 210-290 Ohm : KEYCODE_VOLUME_UP
  • 360-680 Ohm : KEYCODE_VOLUME_DOWN
• SHOULD support the detection and mapping to the keycode for the following range of equivalent impedance between the microphone and ground conductors on the audio plug:
  • 110-180 Ohm: KEYCODE_VOICE_ASSIST
• MUST trigger ACTION_HEADSET_PLUG upon a plug insert, but only after all contacts on plug are touching their relevant segments on the jack.
• MUST be capable of driving at least 150mV +/- 10% of output voltage on a 32 Ohm speaker impedance.
• MUST have a microphone bias voltage between 1.8V ~ 2.9V.

8. Performance Compatibility

Some minimum performance criteria are critical to the user experience and impacts the baseline assumptions developers would have when developing an app. Android Watch devices SHOULD and other type of device implementations MUST meet the following criteria:

8.1.使用者體驗一致性

Device implementations MUST provide a smooth user interface by ensuring a consistent frame rate and response times for applications and games. Device implementations MUST meet the following requirements:

• Consistent frame latency .不一致的幀延遲或渲染幀延遲的發生頻率不得超過每秒 5 幀，且應低於每秒 1 幀。
• User interface latency . Device implementations MUST ensure low latency user experience by scrolling a list of 10K list entries as defined by the Android Compatibility Test Suite (CTS) in less than 36 secs.
• 任務切換。 When multiple applications have been launched, re-launching an already-running application after it has been launched MUST take less than 1 second.

8.2.文件 I/O 存取效能

Device implementations MUST ensure internal storage file access performance consistency for read and write operations.

• Sequential write . Device implementations MUST ensure a sequential write performance of at least 5MB/s for a 256MB file using 10MB write buffer.
• Random write . Device implementations MUST ensure a random write performance of at least 0.5MB/s for a 256MB file using 4KB write buffer.
• Sequential read . Device implementations MUST ensure a sequential read performance of at least 15MB/s for a 256MB file using 10MB write buffer.
• Random read . Device implementations MUST ensure a random read performance of at least 3.5MB/s for a 256MB file using 4KB write buffer.

9. Security Model Compatibility

Device implementations MUST implement a security model consistent with the Android platform security model as defined in Security and Permissions reference document in the APIs [ Resources, 102 ] in the Android developer documentation. Device implementations MUST support installation of self-signed applications without requiring any additional permissions/certificates from any third parties/authorities. Specifically, compatible devices MUST support the security mechanisms described in the follow subsections.

9.1.權限

Device implementations MUST support the Android permissions model as defined in the Android developer documentation [ Resources, 102 ]. Specifically, implementations MUST enforce each permission defined as described in the SDK documentation; no permissions may be omitted, altered, or ignored. Implementations MAY add additional permissions, provided the new permission ID strings are not in the android.* namespace.

9.2. UID 和進程隔離

Device implementations MUST support the Android application sandbox model, in which each application runs as a unique Unixstyle UID and in a separate process. Device implementations MUST support running multiple applications as the same Linux user ID, provided that the applications are properly signed and constructed, as defined in the Security and Permissions reference [ Resources, 102 ].

9.3.檔案系統權限

Device implementations MUST support the Android file access permissions model as defined in the Security and Permissions reference [ Resources, 102 ].

9.4. Alternate Execution Environments

Device implementations MAY include runtime environments that execute applications using some other software or technology than the Dalvik Executable Format or native code. However, such alternate execution environments MUST NOT compromise the Android security model or the security of installed Android applications, as described in this section.

Alternate runtimes MUST themselves be Android applications, and abide by the standard Android security model, as described elsewhere in section 9 .

Alternate runtimes MUST NOT be granted access to resources protected by permissions not requested in the runtime's AndroidManifest.xml file via the <uses-permission> mechanism.

Alternate runtimes MUST NOT permit applications to make use of features protected by Android permissions restricted to system applications.

Alternate runtimes MUST abide by the Android sandbox model. Specifically, alternate runtimes:

• SHOULD install apps via the PackageManager into separate Android sandboxes ( Linux user IDs, etc.).
• MAY provide a single Android sandbox shared by all applications using the alternate runtime.
• and installed applications using an alternate runtime, MUST NOT reuse the sandbox of any other app installed on the device, except through the standard Android mechanisms of shared user ID and signing certificate.
• MUST NOT launch with, grant, or be granted access to the sandboxes corresponding to other Android applications.
• MUST NOT be launched with, be granted, or grant to other applications any privileges of the superuser (root), or of any other user ID.

The .apk files of alternate runtimes MAY be included in the system image of a device implementation, but MUST be signed with a key distinct from the key used to sign other applications included with the device implementation.

When installing applications, alternate runtimes MUST obtain user consent for the Android permissions used by the application. If an application needs to make use of a device resource for which there is a corresponding Android permission (such as Camera, GPS, etc.), the alternate runtime MUST inform the user that the application will be able to access that resource. If the runtime environment does not record application capabilities in this manner, the runtime environment MUST list all permissions held by the runtime itself when installing any application using that runtime.

9.5。 Multi-User Support

Android includes support for multiple users and provides support for full user isolation [ Resources, 103] . Device implementations MAY enable multiple users, but when enabled MUST meet the following requirements related to multi-user support [ Resources, 104 ]:

• Device implementations that do not declare the android.hardware.telephony feature flag MUST support restricted profiles, a feature that allows device owners to manage additional users and their capabilities on the device.透過受限設定文件，裝置擁有者可以快速設定單獨的環境供其他使用者工作，並能夠管理這些環境中可用的應用程式中的更細粒度的限制。
• Conversely device implementations that declare the android.hardware.telephony feature flag MUST NOT support restricted profiles but MUST align with the AOSP implementation of controls to enable /disable other users from accessing the voice calls and SMS.
• Device implementations MUST, for each user, implement a security model consistent with the Android platform security model as defined in Security and Permissions reference document in the APIs [ Resources, 102 ].
• Device implementations MAY support creating users and managed profiles via the android.app.admin.DevicePolicyManager APIs, and if supported, MUST declare the platform feature flag android.software.managed_users.
• Device implementations that declare the feature flag android.software.managed_users MUST use the upstream AOSP icon badge to represent the managed applications and other badge UI elements like Recents & Notifications.
• Each user instance on an Android device MUST have separate and isolated external storage directories. Device implementations MAY store multiple users' data on the same volume or filesystem. However, the device implementation MUST ensure that applications owned by and running on behalf a given user cannot list, read, or write to data owned by any other user. Note that removable media, such as SD card slots, can allow one user to access another's data by means of a host PC. For this reason, device implementations that use removable media for the primary external storage APIs MUST encrypt the contents of the SD card if multiuser is enabled using a key stored only on non-removable media accessible only to the system. As this will make the media unreadable by a host PC, device implementations will be required to switch to MTP or a similar system to provide host PCs with access to the current user's data. Accordingly, device implementations MAY but SHOULD NOT enable multi-user if they use removable media [ Resources, 105 ] for primary external storage.

9.6。 Premium SMS Warning

Android includes support for warning users of any outgoing premium SMS message [ Resources, 106 ] . Premium SMS messages are text messages sent to a service registered with a carrier that may incur a charge to the user. Device implementations that declare support for android.hardware.telephony MUST warn users before sending a SMS message to numbers identified by regular expressions defined in /data/misc/sms/codes.xml file in the device. The upstream Android Open Source Project provides an implementation that satisfies this requirement.

9.7. Kernel Security Features

The Android Sandbox includes features that can use the Security-Enhanced Linux (SELinux) mandatory access control (MAC) system and other security features in the Linux kernel. SELinux or any other security features, if implemented below the Android framework:

• MUST maintain compatibility with existing applications.
• MUST NOT have a visible user interface when a security violation is detected and successfully blocked, but MAY have a visible user interface when an unblocked security violation occurs resulting in a successful exploit.
• SHOULD NOT be user or developer configurable.

If any API for configuration of policy is exposed to an application that can affect another application (such as a Device Administration API), the API MUST NOT allow configurations that break compatibility.

Devices MUST implement SELinux or an equivalent mandatory access control system if using a kernel other than Linux and meet the following requirements, which are satisfied by the reference implementation in the upstream Android Open Source Project.

設備實現：

• MUST support a SELinux policy that allows the SELinux mode to be set on a per-domain basis, and MUST configure all domains in enforcing mode. No permissive mode domains are allowed, including domains specific to a device/vendor.
• SHOULD load policy from /sepolicy file on the device.
• MUST NOT modify, omit, or replace the neverallow rules present within the sepolicy file provided in the upstream Android Open Source Project (AOSP) and the policy MUST compile with all neverallow present, for both AOSP SEL5 。
• MUST support dynamic updates of the SELinux policy file without requiring a system image update.

Device implementations SHOULD retain the default SELinux policy provided in the upstream Android Open Source Project, until they have first audited their additions to the SELinux policy. Device implementations MUST be compatible with the upstream Android Open Source Project.

9.8.隱私

If the device implements functionality in the system that captures the contents displayed on the screen and/or records the audio stream played on the device, it MUST continuously notify the user whenever this functionality is enabled and actively capturing/recording.

If a device implementation has a mechanism that routes network data traffic through a proxy server or VPN gateway by default (for example, preloading a traffic through a proxy server or VPN gateway by default (for example, preloading a mple service with android.VPNmission.CONTROL_VPN that機制。

9.9.全碟加密

If the device implementation supports a lock screen with PIN (numeric) or PASSWORD (alphanumeric), the device MUST support full-disk encryption of the application private data (/data partition), as well as the SD card partition if it is a permanent, non-removable part of the device [ Resources, 107 ]. For devices supporting full-disk encryption, the full-disk encryption SHOULD be enabled all the time after the user has completed the out-of-box experience. While this requirement is stated as SHOULD for this version of the Android platform, it is very strongly RECOMMENDED as we expect this to change to MUST in the future versions of Android. Encryption MUST use AES with a key of 128-bits (or greater) and a mode designed for storage (for example, AES-XTS, AES-CBC-ESSIV). The encryption key MUST NOT be written to storage at any time without being encrypted. Other than when in active use, the encryption key SHOULD be AES encrypted with the lockscreen passcode stretched using a slow stretching algorithm (eg PBKDF2 or scrypt). If the user has not specified a lockscreen passcode or has disabled use of the passcode for encryption, the system SHOULD use a default passcode to wrap the encryption key. If the device provides a hardware-backed keystore, the password stretching algorithm MUST be cryptographically bound to that keystore. The encryption key MUST NOT be sent off the device (even when wrapped with the user passcode and/or hardware bound key). The upstream Android Open Source project provides a preferred implementation of this feature based on the linux kernel feature dm-crypt.

9.10。驗證啟動

Verified boot is a feature that guarantees the integrity of the device software. If a device implementation supports the feature, it MUST:

• Declare the platform feature flag android.software.verified_boot
• Perform verification on every boot sequence
• Start verification from a hardware key that is the root of trust, and go all the way up to the system partition
• Implement each stage of verification to check the integrity and authenticity of all the bytes in the next stage before executing the code in the next stage
• Use verification algorithms as strong as current recommendations from NIST for hashing algorithms (SHA-256) and public key sizes (RSA-2048)

Device implementations SHOULD support verified boot for device integrity. While this requirement is SHOULD for this version of the Android platform, it is strongly RECOMMENDED as we expect this to change to MUST in future versions of Android. The upstream Android Open Source Project provides a preferred implementation of this feature based on the linux kernel feature dm-verity.

10. Software Compatibility Testing

Device implementations MUST pass all tests described in this section.

However, note that no software test package is fully comprehensive. For this reason, device implementers are very strongly encouraged to make the minimum number of changes as possible to the reference and preferred implementation of Android available from the Android Open Source Project. This will minimize the risk of introducing bugs that create incompatibilities requiring rework and potential device updates.

10.1.相容性測試套件

Device implementations MUST pass the Android Compatibility Test Suite (CTS) [ Resources, 108 ] available from the Android Open Source Project, using the final shipping software on the device. Additionally, device implementers SHOULD use the reference implementation in the Android Open Source tree as much as possible, and MUST ensure compatibility in cases of ambiguity in CTS and for any reimplementations of parts of the reference source code.

The CTS is designed to be run on an actual device. Like any software, the CTS may itself contain bugs. The CTS will be versioned independently of this Compatibility Definition, and multiple revisions of the CTS may be released for Android 5.1. Device implementations MUST pass the latest CTS version available at the time the device software is completed.

10.2. CTS驗證器

Device implementations MUST correctly execute all applicable cases in the CTS Verifier. The CTS Verifier is included with the Compatibility Test Suite, and is intended to be run by a human operator to test functionality that cannot be tested by an automated system, such as correct functioning of a camera and sensors.

The CTS Verifier has tests for many kinds of hardware, including some hardware that is optional. Device implementations MUST pass all tests for hardware that they possess; for instance, if a device possesses an accelerometer, it MUST correctly execute the Accelerometer test case in the CTS Verifier. Test cases for features noted as optional by this Compatibility Definition Document MAY be skipped or omitted.

Every device and every build MUST correctly run the CTS Verifier, as noted above. However, since many builds are very similar, device implementers are not expected to explicitly run the CTS Verifier on builds that differ only in trivial ways. Specifically, device implementations that differ from an implementation that has passed the CTS Verifier only by the set of included locales, branding, etc. MAY omit the CTS Verifier test.

11. 可更新的軟體

Device implementations MUST include a mechanism to replace the entirety of the system software. The mechanism need not perform “live” upgrades—that is, a device restart MAY be required.

Any method can be used, provided that it can replace the entirety of the software preinstalled on the device. For instance, any of the following approaches will satisfy this requirement:

• “Over-the-air (OTA)” downloads with offline update via reboot
• “Tethered” updates over USB from a host PC
• “Offline” updates via a reboot and update from a file on removable storage

However, if the device implementation includes support for an unmetered data connection such as 802.11 or Bluetooth PAN (Personal Area Network) profile:

• Android Automotive implementations SHOULD support OTA downloads with offline update via reboot.
• All other device implementations MUST support OTA downloads with offline update via reboot.

The update mechanism used MUST support updates without wiping user data. That is, the update mechanism MUST preserve application private data and application shared data. Note that the upstream Android software includes an update mechanism that satisfies this requirement.

For device implementations that are launching with Android 5.1 and later, the update mechanism SHOULD support verifying that the system image is binary identical to expected result following an OTA.上游Android開源專案中自Android 5.1以來新增的基於區塊的OTA實作滿足了這項要求。

If an error is found in a device implementation after it has been released but within its reasonable product lifetime that is determined in consultation with the Android Compatibility Team to affect the compatibility of third-party applications, the device implementer MUST correct the error via a software update available that can be applied per the mechanism just described.

12. Document Changelog

The following table contains a summary of the changes to the Compatibility Definition in this release.

13. Contact Us

You can join the android-compatibility forum [Resources, 109 ] and ask for clarifications or bring up any issues that you think the document does not cover.

14. Resources

1. IETF RFC2119 Requirement Levels: http://www.ietf.org/rfc/rfc2119.txt

2. Android Open Source Project: http://source.android.com/

3. Android Television features: http://developer.android.com/reference/android/content/pm/PackageManager.html#FEATURE_LEANBACK

4. Android Watch feature: http://developer.android.com/reference/android/content/res/Configuration.html#UI_MODE_TYPE_WATCH

5. API definitions and documentation: http://developer.android.com/reference/packages.html

6. Android Permissions reference: http://developer.android.com/reference/android/Manifest.permission.html

7. android.os.Build reference: http://developer.android.com/reference/android/os/Build.html

8. Android 5.1 allowed version strings: http://source.android.com/compatibility/5.1/versions.html

9. Telephony Provider: http://developer.android.com/reference/android/provider/Telephony.html

10. Host-based Card Emulation: http://developer.android.com/guide/topics/connectivity/nfc/hce.html

11. Android Extension Pack: http://developer.android.com/guide/topics/graphics/opengl.html#aep

12. android.webkit.WebView class: http://developer.android.com/reference/android/webkit/WebView.html

13. WebView compatibility: http://www.chromium.org/

14. HTML5: http://html.spec.whatwg.org/multipage/

15. HTML5 offline capabilities: http://dev.w3.org/html5/spec/Overview.html#offline

16. HTML5 video tag: http://dev.w3.org/html5/spec/Overview.html#video

17. HTML5/W3C geolocation API: http://www.w3.org/TR/geolocation-API/

18. HTML5/W3C webstorage API: http://www.w3.org/TR/webstorage/

19. HTML5/W3C IndexedDB API: http://www.w3.org/TR/IndexedDB/

20. Dalvik Executable Format and bytecode specification: available in the Android source code, at dalvik/docs

21. AppWidgets: http://developer.android.com/guide/practices/ui_guidelines/widget_design.html

22. Notifications: http://developer.android.com/guide/topics/ui/notifiers/notifications.html

23. Application Resources: https://developer.android.com/guide/topics/resources/available-resources.html

24. Status Bar icon style guide: http://developer.android.com/design/style/iconography.html

25. Notifications Resources: https://developer.android.com/design/patterns/notifications.html

26. Search Manager: http://developer.android.com/reference/android/app/SearchManager.html

27. Toasts: http://developer.android.com/reference/android/widget/Toast.html

28. Themes: http://developer.android.com/guide/topics/ui/themes.html

29. R.style class: http://developer.android.com/reference/android/R.style.html

30. Material design: http://developer.android.com/reference/android/R.style.html#Theme_Material

31. Live Wallpapers: http://developer.android.com/reference/android/service/wallpaper/WallpaperService.html

32. Overview screen resources: http://developer.android.com/guide/components/recents.html

33. Screen pinning: https://developer.android.com/about/versions/android-5.0.html#ScreenPinning

34. Input methods: http://developer.android.com/guide/topics/text/creating-input-method.html

35. Media Notification: https://developer.android.com/reference/android/app/Notification.MediaStyle.html

36. Dreams: http://developer.android.com/reference/android/service/dreams/DreamService.html

37. Settings.Secure LOCATION_MODE:

http://developer.android.com/reference/android/provider/Settings.Secure.html#LOCATION_MODE

38. Unicode 6.1.0: http://www.unicode.org/versions/Unicode6.1.0/

39. Android Device Administration: http://developer.android.com/guide/topics/admin/device-admin.html

40. DevicePolicyManager reference: http://developer.android.com/reference/android/app/admin/DevicePolicyManager.html

41. Android Device Owner App:

http://developer.android.com/reference/android/app/admin/DevicePolicyManager.html#isDeviceOwnerApp(java.lang.String)

42. Android Accessibility Service APIs: http://developer.android.com/reference/android/accessibilityservice/AccessibilityService.html

43. Android Accessibility APIs: http://developer.android.com/reference/android/view/accessibility/package-summary.html

44. Eyes Free project: http://code.google.com/p/eyes-free

45. Text-To-Speech APIs: http://developer.android.com/reference/android/speech/tts/package-summary.html

46. Television Input Framework: /devices/tv/index.html

47. Reference tool documentation (for adb, aapt, ddms, systrace): http://developer.android.com/tools/help/index.html

48. Android apk file description: http://developer.android.com/guide/components/fundamentals.html

49. Manifest files: http://developer.android.com/guide/topics/manifest/manifest-intro.html

50. Android Media Formats: http://developer.android.com/guide/appendix/media-formats.html

51. RTC Hardware Coding Requirements: http://www.webmproject.org/hardware/rtc-coding-requirements/

52. AudioEffect API: http://developer.android.com/reference/android/media/audiofx/AudioEffect.html

53. Android android.content.pm.PackageManager class and Hardware Features List:

http://developer.android.com/reference/android/content/pm/PackageManager.html

54. HTTP Live Streaming Draft Protocol: http://tools.ietf.org/html/draft-pantos-http-live-streaming-03

55. ADB: http://developer.android.com/tools/help/adb.html

56. Dumpsys: /devices/input/diagnostics.html

57. DDMS: http://developer.android.com/tools/debugging/ddms.html

58. Monkey testing tool: http://developer.android.com/tools/help/monkey.html

59. SysyTrace tool: http://developer.android.com/tools/help/systrace.html

60. Android Application Development-Related Settings:

http://developer.android.com/reference/android/provider/Settings.html#ACTION_APPLICATION_DEVELOPMENT_SETTINGS

61. Supporting Multiple Screens: http://developer.android.com/guide/practices/screens_support.html

62. android.util.DisplayMetrics: http://developer.android.com/reference/android/util/DisplayMetrics.html

63. RenderScript: http://developer.android.com/guide/topics/renderscript/

64. Android extension pack for OpenGL ES: https://developer.android.com/reference/android/opengl/GLES31Ext.html

65. Hardware Acceleration: http://developer.android.com/guide/topics/graphics/hardware-accel.html

66. EGL Extension-EGL_ANDROID_RECORDABLE:

http://www.khronos.org/registry/egl/extensions/ANDROID/EGL_ANDROID_recordable.txt

67. Display Manager: http://developer.android.com/reference/android/hardware/display/DisplayManager.html

68. android.content.res.Configuration: http://developer.android.com/reference/android/content/res/Configuration.html

69. Action Assist: http://developer.android.com/reference/android/content/Intent.html#ACTION_ASSIST

70. Touch Input Configuration: http://source.android.com/devices/tech/input/touch-devices.html

71. Motion Event API: http://developer.android.com/reference/android/view/MotionEvent.html

72. Key Event API: http://developer.android.com/reference/android/view/KeyEvent.html

73. Android Open Source sensors: http://source.android.com/devices/sensors

74. android.hardware.SensorEvent: http://developer.android.com/reference/android/hardware/SensorEvent.html

75. Timestamp sensor event: http://developer.android.com/reference/android/hardware/SensorEvent.html#timestamp

76. Android Open Source composite sensors: /devices/sensors/sensor-types.html#composite_sensor_type_summary

77. Continuous trigger mode: /docs/core/interaction/sensors/report-modes#continuous

78. Accelerometer sensor: http://developer.android.com/reference/android/hardware/Sensor.html#TYPE_ACCELEROMETER

79. Wi-Fi Multicast API: http://developer.android.com/reference/android/net/wifi/WifiManager.MulticastLock.html

80. Wi-Fi Direct (Wi-Fi P2P): http://developer.android.com/reference/android/net/wifi/p2p/WifiP2pManager.html

81. WifiManager API: http://developer.android.com/reference/android/net/wifi/WifiManager.html

82. Bluetooth API: http://developer.android.com/reference/android/bluetooth/package-summary.html

83. Bluetooth ScanFilter API: https://developer.android.com/reference/android/bluetooth/le/ScanFilter.html

84. NDEF Push Protocol: http://source.android.com/compatibility/ndef-push-protocol.pdf

85. Android Beam: http://developer.android.com/guide/topics/connectivity/nfc/nfc.html

86. Android NFC Sharing Settings:

http://developer.android.com/reference/android/provider/Settings.html#ACTION_NFCSHARING_SETTINGS

87. NFC Connection Handover: http://members.nfc-forum.org/specs/spec_list/#conn_handover

88. Bluetooth Secure Simple Pairing Using NFC: http://members.nfc-forum.org/apps/group_public/download.php/18688/NFCForum-AD-BTSSP_1_1.pdf

89. Content Resolver: http://developer.android.com/reference/android/content/ContentResolver.html

90. Camera orientation API: http://developer.android.com/reference/android/hardware/Camera.html#setDisplayOrientation(int)

91. Camera: http://developer.android.com/reference/android/hardware/Camera.html

92. Camera: http://developer.android.com/reference/android/hardware/Camera.Parameters.html

93. Camera hardware level: https://developer.android.com/reference/android/hardware/camera2/CameraCharacteristics.html#INFO_SUPPORTED_HARDWARE_LEVEL

94. Camera version support: http://source.android.com/devices/camera/versioning.html

95. Android DownloadManager: http://developer.android.com/reference/android/app/DownloadManager.html

96. Android File Transfer: http://www.android.com/filetransfer

97. Android Open Accessories: http://developer.android.com/guide/topics/connectivity/usb/accessory.html

98. Android USB Audio: http://developer.android.com/reference/android/hardware/usb/UsbConstants.html#USB_CLASS_AUDIO

99. USB Charging Specification: http://www.usb.org/developers/docs/devclass_docs/USB_Battery_Charging_1.2.pdf

100. USB Host API: http://developer.android.com/guide/topics/connectivity/usb/host.html

101. Wired audio headset: http://source.android.com//docs/core/interaction/accessories/headset/plug-headset-spec.html

102. Android Security and Permissions reference: http://developer.android.com/guide/topics/security/permissions.html

103. UserManager reference: http://developer.android.com/reference/android/os/UserManager.html

104. External Storage reference: http://source.android.com/docs/core/storage

105. External Storage APIs: http://developer.android.com/reference/android/os/Environment.html

106. SMS Short Code: http://en.wikipedia.org/wiki/Short_code

107. Android Open Source Encryption: http://source.android.com/docs/security/features/encryption

108. Android Compatibility Program Overview: http://source.android.com//docs/compatibility

109. Android Compatibility forum: https://groups.google.com/forum/#!forum/android-compatibility

110. WebM project: http://www.webmproject.org/

111. Android UI_MODE_TYPE_CAR API: http://developer.android.com/reference/android/content/res/Configuration.html#UI_MODE_TYPE_CAR

112. Android MediaCodecList API: http://developer.android.com/reference/android/media/MediaCodecList.html

113. Android CamcorderProfile API: http://developer.android.com/reference/android/media/CamcorderProfile.html

Many of these resources are derived directly or indirectly from the Android SDK, and will be functionally identical to the information in that SDK's documentation.在任何情況下，如果本相容性定義或相容性測試套件與 SDK 文件不一致，則 SDK 文件被視為具有權威性。 Any technical details provided in the references included above are considered by inclusion to be part of this Compatibility Definition.