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

Apps running on Android 17 or higher that target Android 17 (API level 37) or higher cannot change static final fields. If an app attempts to change a static final field by using reflection, it will cause an IllegalAccessException. Attempting to modify one of these fields through JNI APIs (such as SetStaticLongField()) will cause the app to crash.

无障碍

Android 17 进行了以下变更，以改进无障碍功能。

支持复杂 IME 实体键盘输入的无障碍功能

This feature introduces new AccessibilityEvent and TextAttribute APIs to enhance screen reader spoken feedback for CJKV language input. CJKV IME apps can now signal whether a text conversion candidate has been selected during text composition. Apps with edit fields can specify text change types when sending text changed accessibility events. For example, apps can specify that a text change occurred during text composition, or that a text change resulted from a commit. Doing this enables accessibility services such as screen readers to deliver more precise feedback based on the nature of the text modification.

App adoption

  • IME Apps: When setting composing text in edit fields, IMEs can use TextAttribute.Builder.setTextSuggestionSelected() to indicate whether a specific conversion candidate was selected.

  • Apps with Edit Fields: Apps that maintain a custom InputConnection can retrieve candidate selection data by calling TextAttribute.isTextSuggestionSelected(). These apps should then call AccessibilityEvent.setTextChangeTypes() when dispatching TYPE_VIEW_TEXT_CHANGED events. Apps targeting Android 17 (API level 37) that use the standard TextView will have this feature enabled by default. (That is, TextView will handle retrieving data from the IME and setting text change types when sending events to accessibility services).

  • Accessibility Services: Accessibility services that process TYPE_VIEW_TEXT_CHANGED events can call AccessibilityEvent.getTextChangeTypes() to identify the nature of the modification and adjust their feedback strategies accordingly.

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 introduces platform support for Encrypted Client Hello (ECH), a TLS extension that enhances user privacy by encrypting the Server Name Indication (SNI) in the TLS handshake. This encryption helps prevent network observers from easily identifying the specific domain your app is connecting to.

For apps targeting Android 17 (API level 37) or higher, ECH is opportunistically used for TLS connections. ECH is active only if the networking library used by the app (for example, HttpEngine, WebView, or OkHttp) has integrated ECH support and the remote server also supports the ECH protocol. If ECH cannot be negotiated, the connection automatically falls back to a standard TLS handshake without SNI encryption.

To allow apps to customize this behavior, Android 17 adds a new <domainEncryption> element to the Network Security Configuration file. Developers can use <domainEncryption> within <base-config> or <domain-config> tags to select an ECH mode (for example, "opportunistic", "enabled", or "disabled") on a global or per-domain basis.

For more information, see the Encrypted Client Hello documentation.

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

If an app targets Android 17 (API level 37) or higher and the user is using a physical input device (for example, an external keyboard), the Android operating system applies the new show_passwords_physical setting to all characters in the password field. By default, that setting hides all password characters.

The Android system shows the last-typed password character to help the user see if they mistyped the password. However, this is much less necessary with larger external keyboards. In addition, devices with external keyboards often have larger displays, which increases the danger of someone seeing the typed password.

If the user is using the device's touchscreen, the system applies the new show_passwords_touch setting.

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

If an app targets Android 17 (API level 37) or higher, certificate transparency (CT) is enabled by default. (On Android 16, CT is available but apps had to opt in.)

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

For apps targeting Android 17 (API level Android 17 (API level 37)) and higher, Contacts Provider 2 (CP2) restricts certain columns containing Personally Identifiable Information (PII) from the data view. When this change is enabled, these columns are removed from the data view to enhance user privacy. The restricted columns include:

Apps that are using these columns from ContactsContract.Data can extract them from ContactsContract.RawContacts instead, by joining with RAW_CONTACT_ID.

在 CP2 中强制执行严格的 SQL 检查

对于以 Android 17（API 级别 37）及更高版本为目标平台的应用，当在没有 READ_CONTACTS 权限的情况下访问 ContactsContract.Data 表时，联系人提供程序 2 (CP2) 会强制执行严格的 SQL 查询验证。

在此项更改生效后，如果应用没有 READ_CONTACTS 权限，则在查询 ContactsContract.Data 表时会设置 StrictColumns 和 StrictGrammar 选项。如果查询使用的模式与这些模式不兼容，则会被拒绝并导致抛出异常。

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

我们在 Android 16 中引入了平台 API 变更，以 忽略屏幕方向、 宽高比和尺寸调整能力限制（针对大型屏幕，sw >= 600dp），适用于面向 API 级别 36 或更高级别的应用。开发者可以选择使用 SDK 36 退出这些变更，但对于面向 Android 17（API 级别 37）或更高级别的应用，此退出选项将不再可用。

如需了解详情，请参阅忽略屏幕方向和尺寸调整能力限制。

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.