行为变更：以 Android 17 或更高版本为目标平台的应用

与之前的版本一样，Android 17 包含一些可能会影响应用的行为变更。以下行为变更仅影响以 Android 17 或更高版本为目标平台的应用。如果应用以 Android 17 或更高版本为目标平台，则应根据情况修改应用，以支持这些行为。

无论应用的 targetSdkVersion 为何，都请务必查看对 Android 17 上运行的所有应用都有影响的行为变更列表。

核心功能

Android 17 包含以下变更，这些变更会修改或扩展 Android 系统的各种核心功能。

MessageQueue 的新无锁实现

Beginning with Android 17, apps targeting Android 17 (API level 37) or higher receive a new lock-free implementation of android.os.MessageQueue. The new implementation improves performance and reduces missed frames, but may break clients that reflect on MessageQueue private fields and methods.

For more information, including mitigation strategies, see MessageQueue behavior change guidance.

静态 final 字段现在不可修改

在以 Android 17（API 级别 37）或更高版本为目标平台的 Android 17 或更高版本上运行的应用无法更改 static final 字段。如果应用尝试使用反射更改 static final 字段，则会导致 IllegalAccessException。尝试通过 JNI API（例如 SetStaticLongField()）修改其中一个字段会导致应用崩溃。

无障碍

Android 17 进行了以下变更，以改进无障碍功能。

此功能引入了新的 AccessibilityEvent 和 TextAttribute API，以增强屏幕阅读器针对 CJKV 语言输入的语音反馈。CJKV IME 应用现在可以指示在文本撰写期间是否已选择文本转换候选内容。具有编辑字段的应用可以在发送文本更改无障碍事件时指定文本更改类型。例如，应用可以指定在文本撰写期间发生了文本更改，或者文本更改是由提交导致的。这样做可让屏幕阅读器等无障碍服务根据文本修改的性质提供更精确的反馈。

应用采用量

IME 应用：在编辑字段中设置正在撰写的文本时，IME 可以使用 TextAttribute.Builder.setTextSuggestionSelected() 来指明是否选择了特定的转换候选对象。
具有“编辑字段”权限的应用：维护自定义 InputConnection 的应用可以通过调用 TextAttribute.isTextSuggestionSelected() 来检索候选选择数据。然后，这些应用在调度 TYPE_VIEW_TEXT_CHANGED 事件时应调用 AccessibilityEvent.setTextChangeTypes()。如果应用以 Android 17（API 级别 37）为目标平台，并使用标准 TextView，则默认启用此功能。（也就是说，TextView 将负责从 IME 检索数据，并在向无障碍服务发送事件时设置文本更改类型）。
无障碍服务：处理 TYPE_VIEW_TEXT_CHANGED 事件的无障碍服务可以调用 AccessibilityEvent.getTextChangeTypes() 来识别修改的性质，并相应地调整其反馈策略。

隐私权

Android 17 包含以下变更，以改进用户隐私保护。

机会性启用 ECH（加密客户端 Hello）

Android 17 引入了对加密客户端问候 (ECH) 的平台支持。ECH 是一种 TLS 扩展，可通过加密 TLS 握手中的服务器名称指示 (SNI) 来增强用户隐私保护。这种加密有助于防止网络观察者轻松识别您的应用所连接的特定网域。

对于以 Android 17（API 级别 37）或更高版本为目标平台的应用，ECH 会机会性地用于 TLS 连接。只有当应用使用的网络库（例如 HttpEngine、WebView 或 OkHttp）已集成 ECH 支持，并且远程服务器也支持 ECH 协议时，ECH 才会处于活跃状态。如果无法协商 ECH，连接会自动回退到不使用 SNI 加密的标准 TLS 握手。

为了让应用能够自定义此行为，Android 17 向网络安全配置文件添加了一个新的 <domainEncryption> 元素。开发者可以在 <base-config> 或 <domain-config> 标记中使用 <domainEncryption>，以全局或按网域的方式选择 ECH 模式（例如 "opportunistic"、"enabled" 或 "disabled"）。

如需了解详情，请参阅加密客户端问候文档。

以 Android 17 为目标平台的应用需要本地网络权限

Android 17 introduces the ACCESS_LOCAL_NETWORK runtime permission to protect users from unauthorized local network access. Because this falls under the existing NEARBY_DEVICES permission group, users who have already granted other NEARBY_DEVICES permissions aren't prompted again. This new requirement prevents malicious apps from exploiting unrestricted local network access for covert user tracking and fingerprinting. By declaring and requesting this permission, your app can discover and connect to devices on the local area network (LAN), such as smart home devices or casting receivers.

Apps targeting Android 17 (API level 37) or higher now have two paths to maintain communication with LAN devices: Adopt system-mediated, privacy-preserving device pickers to skip the permission prompt, or explicitly request this new permission at runtime to maintain local network communication.

For more information, see the Local network permission documentation.

在实体设备上隐藏密码

如果应用以 Android 17（API 级别 37）或更高版本为目标平台，并且用户使用的是实体输入设备（例如外接键盘），Android 操作系统会对密码字段中的所有字符应用新的 show_passwords_physical 设置。默认情况下，该设置会隐藏所有密码字符。

Android 系统会显示用户最后输入的密码字符，以帮助用户查看是否输错了密码。不过，对于较大的外接键盘，此功能就没那么必要了。此外，配备外接键盘的设备通常具有较大的显示屏，这会增加他人看到输入密码的风险。

如果用户使用的是设备触摸屏，系统会应用新的 show_passwords_touch 设置。

安全

Android 17 对设备和应用安全性进行了以下改进。

Activity 安全性

In Android 17, the platform continues its shift toward a "secure-by-default" architecture, introducing a suite of enhancements designed to mitigate high-severity exploits such as phishing, interaction hijacking, and confused deputy attacks. This update requires developers to explicitly opt in to new security standards to maintain app compatibility and user protection.

Key impacts for developers include:

BAL hardening & improved opt-in: We are refining Background Activity Launch (BAL) restrictions by extending protections to IntentSender. Developers must migrate away from the legacy MODE_BACKGROUND_ACTIVITY_START_ALLOWED constant. Instead, you should adopt granular controls like MODE_BACKGROUND_ACTIVITY_START_ALLOW_IF_VISIBLE, which restricts activity starts to scenarios where the calling app is visible, significantly reducing the attack surface.
Adoption tools: Developers should utilize strict mode and updated lint checks to identify legacy patterns and ensure readiness for future target SDK requirements.

默认启用 CT

如果应用以 Android 17（API 级别 37）或更高版本为目标平台，则默认启用证书透明度 (CT)。（在 Android 16 上，CT 可用，但应用必须选择启用。）

更安全的原生 DCL-C

If your app targets Android 17 (API level 37) or higher, the Safer Dynamic Code Loading (DCL) protection introduced in Android 14 for DEX and JAR files now extends to native libraries.

All native files loaded using System.load() must be marked as read-only. Otherwise, the system throws UnsatisfiedLinkError.

We recommend that apps avoid dynamically loading code whenever possible, as doing so greatly increases the risk that an app can be compromised by code injection or code tampering.

限制 CP2 数据视图中的 PII 字段

对于以 Android 17（API 级别 Android 17（API 级别 37））及更高版本为目标平台的应用，联系人提供程序 2 (CP2) 会限制数据视图中包含某些个人身份信息 (PII) 的列。启用此变更后，这些列将从数据视图中移除，以增强用户隐私保护。受限列包括：

如果应用正在使用 ContactsContract.Data 中的这些列，则可以通过与 RAW_CONTACT_ID 联接，改为从 ContactsContract.RawContacts 中提取这些列。

在 CP2 中强制执行严格的 SQL 检查

For apps targeting Android 17 (API level Android 17 (API level 37)) and higher, Contacts Provider 2 (CP2) enforces strict SQL query validation when the ContactsContract.Data table is accessed without READ_CONTACTS permission.

With this change, if an app doesn't have READ_CONTACTS permission, StrictColumns and StrictGrammar options are set when querying the ContactsContract.Data table. If a query uses a pattern that isn't compatible with these, it will be rejected and cause an exception to be thrown.

媒体

Android 17 包含以下媒体行为变更。

后台音频安全加固

Beginning with Android 17, the audio framework enforces restrictions on background audio interactions including audio playback, audio focus requests, and volume change APIs to ensure that these changes are started intentionally by the user.

Some audio restrictions apply to all apps. However, the restrictions are more stringent if an app targets Android 17 (API level 37). If one of these apps interacts with audio while it is in the background, it must have a foreground service running. In addition, the app must meet one or both of these requirements:

The foreground service must have while-in-use (WIU) capabilities.
The app must have the exact alarm permission and be interacting with USAGE_ALARM audio streams.

For more information, including mitigation strategies, see Background audio hardening.

设备类型

Android 17 包含以下变更，以改进各种设备尺寸和类型中的用户体验。

平台 API 变更，用于忽略大屏 (sw>=600dp) 上的屏幕方向、尺寸调整能力和宽高比限制

We introduced Platform API changes in Android 16 to ignore orientation, aspect ratio, and resizability restrictions on large screens (sw >= 600dp) for apps targeting API level 36 or higher. Developers have the option to opt out of these changes with SDK 36, but this opt-out will no longer be available for apps that target Android 17 (API level 37) or higher.

For more information, see Restrictions on orientation and resizability are ignored.

连接

Android 17 引入了以下变更，以提高一致性并与蓝牙 RFCOMM 套接字的标准 Java InputStream 行为保持一致。

RFCOMM 的一致 BluetoothSocket read() 行为

For apps targeting Android 17 (API level 37), the read() method of the InputStream obtained from an RFCOMM-based BluetoothSocket now returns -1 when the socket is closed or the connection is dropped.

This change makes RFCOMM socket behavior consistent with LE CoC sockets and aligns with the standard InputStream.read() documentation, which states that -1 is returned when the end of the stream is reached.

Apps that rely solely on catching an IOException to break out of a read loop may be impacted by this change and should update the BluetoothSocket read loops to explicitly check for a return value of -1. This ensures the loop terminates correctly when the remote device disconnects or the socket is closed. For an example of the recommended implementation, see the code snippet in the Transfer Bluetooth data guide.