功能和 API 概览

Android 14 面向开发者引入了一些出色的功能和 API。下文可帮助您了解适用于您的应用的功能并开始使用相关 API。

如需查看已添加、修改和删除的 API 的详细列表,请参阅 API 差异报告。如需详细了解添加的 API,请访问 Android API 参考文档。对于 Android 14,请查找在 API 级别 34 中添加的 API。如需了解平台变更可能会在哪些方面影响您的应用,请务必查看适用于以 Android 14 为目标平台的应用所有应用的 Android 14 行为变更。

国际化

各应用语言偏好设定

Android 14 expands on the per-app language features that were introduced in Android 13 (API level 33) with these additional capabilities:

  • Automatically generate an app's localeConfig: Starting with Android Studio Giraffe Canary 7 and AGP 8.1.0-alpha07, you can configure your app to support per-app language preferences automatically. Based on your project resources, the Android Gradle plugin generates the LocaleConfig file and adds a reference to it in the final manifest file, so you no longer have to create or update the file manually. AGP uses the resources in the res folders of your app modules and any library module dependencies to determine the locales to include in the LocaleConfig file.

  • Dynamic updates for an app's localeConfig: Use the setOverrideLocaleConfig() and getOverrideLocaleConfig() methods in LocaleManager to dynamically update your app's list of supported languages in the device's system settings. Use this flexibility to customize the list of supported languages per region, run A/B experiments, or provide an updated list of locales if your app utilizes server-side pushes for localization.

  • App language visibility for input method editors (IMEs): IMEs can utilize the getApplicationLocales() method to check the language of the current app and match the IME language to that language.

Grammatical Inflection API

有 30 亿人在使用区分性别的语言,此类语言的语法类别(例如名词、动词、形容词和介词)会根据您交谈所涉及的人或物的性别而变化。传统上,许多区分性别的语言使用阳性语法性别作为默认或通用性别。

以错误的语法性别来称呼用户,例如以阳性语法性别来称呼女性,可能会对她们的表现和态度产生负面影响。相比之下,界面语言如果能正确反映用户的语法性别,就可以提高用户互动度,并提供更个性化、更自然的用户体验。

为帮助您针对区分性别的语言构建以用户为中心的界面,Android 14 引入了语法变化 API,让您无需重构应用便能添加对语法性别的支持。

地区偏好设置

Regional preferences enable users to personalize temperature units, the first day of the week, and numbering systems. A European living in the United States might prefer temperature units to be in Celsius rather than Fahrenheit and for apps to treat Monday as the beginning of the week instead of the US default of Sunday.

New Android Settings menus for these preferences provide users with a discoverable and centralized location to change app preferences. These preferences also persist through backup and restore. Several APIs and intents—such as getTemperatureUnit and getFirstDayOfWeek— grant your app read access to user preferences, so your app can adjust how it displays information. You can also register a BroadcastReceiver on ACTION_LOCALE_CHANGED to handle locale configuration changes when regional preferences change.

To find these settings, open the Settings app and navigate to System > Languages & input > Regional preferences.

Regional preferences screen in Android system settings.
Temperature options for regional preferences in Android system settings.

无障碍功能

非线性字体放大至 200%

从 Android 14 开始,系统支持字体放大高达 200%,为弱视用户提供了符合网络内容无障碍指南 (WCAG) 的其他无障碍选项。

为防止屏幕上的大文本元素放大过大,系统会采用非线性放大曲线。这种放大策略意味着大号文本的放大比例不会与较小的文本相同。非线性字体缩放有助于保持不同大小元素之间的比例层次结构,同时缓解高级别线性文本缩放的问题(例如文本被截断或文本因超大显示大小而难以阅读)。

使用非线性字体放大测试应用

在设备的无障碍设置中启用最大字号,以测试应用。

如果您已经使用放大像素 (sp) 单位来定义文本大小,那么这些额外的选项和缩放改进会自动应用于应用中的文本。但是,您仍然应该在启用最大字体大小 (200%) 的情况下执行界面测试,以确保应用正确应用字体大小,并且可以适应更大的字体大小,而不影响易用性。

要启用 200% 字号,请按以下步骤操作:

  1. 打开“设置”应用,然后依次前往无障碍 > 显示大小和文字
  2. 字号选项中,点按加号 (+) 图标,直到启用最大字号设置,如本部分随附的图片所示。

针对文本大小使用放大像素 (sp) 单位

请务必始终以 sp 为单位指定文本大小。当应用使用 sp 单位时,Android 可以应用用户的首选文本大小并相应地缩放。

不要为内边距使用 sp 单位,也不假设隐式内边距定义视图高度:使用非线性字体缩放 sp 尺寸可能不成比例,因此 4sp + 20sp 可能不等于 24sp。

转换放大像素 (sp) 单位

使用 TypedValue.applyDimension() 从 sp 单位转换为像素,并使用 TypedValue.deriveDimension() 将像素转换为 sp。这些方法会自动应用适当的非线性缩放曲线。

避免使用 Configuration.fontScaleDisplayMetrics.scaledDensity 对方程进行硬编码。由于字体缩放是非线性的,因此 scaledDensity 字段不再准确。fontScale 字段应仅用于提供信息,因为字体不再使用单个标量值进行缩放。

对 lineHeight 使用 sp 单位

始终使用 sp 单位(而非 dp)定义 android:lineHeight,以便行高随文本一起缩放。否则,如果您的文本为 sp,而 lineHeight 以 dp 或 px 为单位,则文本无法缩放且看起来狭窄。TextView 会自动更正 lineHeight 以保留您预期的比例,但前提是以 sp 为单位同时定义 textSizelineHeight

摄像头和媒体

图片 Ultra HDR

标准动态范围 (SDR) 与高动态范围 (HDR) 图片质量的示意图。

Android 14 增加了对高动态范围 (HDR) 图片的支持,此类图片可在拍照时保留来自传感器的更多信息,从而实现鲜艳的色彩和更高的对比度。Android 采用 Ultra HDR 格式,这种格式可完全向后兼容 JPEG 图片,允许应用与 HDR 图片无缝互操作,从而根据需要以标准动态范围 (SDR) 显示图片。

当您的应用为其 Activity 窗口选择使用 HDR 界面(通过清单条目或在运行时通过调用 Window.setColorMode())时,框架会自动在 HDR 界面中呈现这些图片。您还可以在支持的设备上拍摄压缩的 Ultra HDR 静态图片。从传感器中恢复的颜色越多,博文中的编辑效果就越灵活。与 Ultra HDR 图片关联的 Gainmap 可用于使用 OpenGL 或 Vulkan 渲染这些图片。

相机扩展程序中的缩放、聚焦、Postview 等更多功能

Android 14 升级并改进了相机扩展,使应用能够处理更长的处理时间,从而能够在支持的设备上使用计算密集型算法(如弱光摄影)改善图像。在使用相机扩展功能时,这些功能可为用户带来更稳健的体验。这些改进措施示例包括:

传感器内缩放

When REQUEST_AVAILABLE_CAPABILITIES_STREAM_USE_CASE in CameraCharacteristics contains SCALER_AVAILABLE_STREAM_USE_CASES_CROPPED_RAW, your app can use advanced sensor capabilities to give a cropped RAW stream the same pixels as the full field of view by using a CaptureRequest with a RAW target that has stream use case set to CameraMetadata.SCALER_AVAILABLE_STREAM_USE_CASES_CROPPED_RAW. By implementing the request override controls, the updated camera gives users zoom control even before other camera controls are ready.

无损 USB 音频

Android 14 开始支持无损音频格式,通过 USB 有线耳机提供发烧级体验。您可以查询 USB 设备的首选混音器属性,注册监听器以监听首选混音器属性的变化,并使用 AudioMixerAttributes 类配置混音器属性。此类表示格式,例如声道掩码、采样率和混音器行为。该类允许直接发送音频,而不进行混音、音量调整或处理效果。

开发者工作效率和工具

Credential Manager

Android 14 添加了 Credential Manager 作为平台 API,并通过使用 Google Play 服务的 Jetpack 库为 Android 4.4(API 级别 19)设备提供了额外的支持。凭据管理器旨在使用 API 通过用户配置的凭据提供程序检索和存储凭据,让用户更轻松地登录。凭据管理器在一个 API 中支持多种登录方法,包括用户名和密码、通行密钥和联合登录解决方案(如“使用 Google 账号登录”)。

通行密钥具有许多优势。例如,通行密钥基于业界标准构建,可在不同的操作系统和浏览器生态系统中使用,还可用于网站和应用。

如需了解详情,请参阅凭据管理器和通行密钥文档以及关于 Credential Manager 和通行密钥的博文

Health Connect

Health Connect 是存储用户健康与健身数据的设备端存储库。它可让用户在喜爱的应用之间共享数据,并且只需一个位置即可控制他们要与这些应用共享哪些数据。

在搭载 Android 14 之前的 Android 版本的设备上,Health Connect 可作为应用从 Google Play 商店下载。从 Android 14 开始,Health Connect 已成为平台的一部分,它通过 Google Play 系统更新接收更新,而无需单独下载。这样一来,您可以经常更新 Health Connect,并且您的应用可以依赖于搭载 Android 14 或更高版本的设备上的 Health Connect。用户可以通过设备的“设置”中访问 Health Connect,并将隐私控制集成到系统设置中。

用户无需在搭载 Android 14 或更高版本的设备上单独下载应用,即可开始使用 Health Connect。
用户可以通过系统设置控制哪些应用有权访问其健康与健身数据。

Health Connect 在 Android 14 中包含多项新功能(例如锻炼路线),可让用户分享可在地图上直观呈现的锻炼路线。路线是指一段时间内保存的位置列表,您的应用可以将路线插入锻炼时段,并将其绑定在一起。为了确保用户能够完全控制这些敏感数据,用户必须允许与其他应用共享个别路由。

如需了解详情,请参阅 Health Connection 文档和有关 Android Health 的新变化的博文。

OpenJDK 17 更新

Android 14 continues the work of refreshing Android's core libraries to align with the features in the latest OpenJDK LTS releases, including both library updates and Java 17 language support for app and platform developers.

The following features and improvements are included:

  • Updated approximately 300 java.base classes to Java 17 support.
  • Text Blocks, which introduce multi-line string literals to the Java programming language.
  • Pattern Matching for instanceof, which allows an object to be treated as having a specific type in an instanceof without any additional variables.
  • Sealed classes, which allow you restrict which classes and interfaces can extend or implement them.

Thanks to Google Play system updates (Project Mainline), over 600 million devices are enabled to receive the latest Android Runtime (ART) updates that include these changes. This is part of our commitment to give apps a more consistent, secure environment across devices, and to deliver new features and capabilities to users independent of platform releases.

Java and OpenJDK are trademarks or registered trademarks of Oracle and/or its affiliates.

针对应用商店的改进

Android 14 introduces several PackageInstaller APIs that allow app stores to improve their user experience.

Request install approval before downloading

Installing or updating an app might require user approval. For example, when an installer making use of the REQUEST_INSTALL_PACKAGES permission attempts to install a new app. In prior Android versions, app stores can only request user approval after APKs are written to the install session and the session is committed.

Starting with Android 14, the requestUserPreapproval() method lets installers request user approval before committing the install session. This improvement lets an app store defer downloading any APKs until after the installation has been approved by the user. Furthermore, once a user has approved installation, the app store can download and install the app in the background without interrupting the user.

Claim responsibility for future updates

The setRequestUpdateOwnership() method allows an installer to indicate to the system that it intends to be responsible for future updates to an app it is installing. This capability enables update ownership enforcement, meaning that only the update owner is permitted to install automatic updates to the app. Update ownership enforcement helps to ensure that users receive updates only from the expected app store.

Any other installer, including those making use of the INSTALL_PACKAGES permission, must receive explicit user approval in order to install an update. If a user decides to proceed with an update from another source, update ownership is lost.

Update apps at less-disruptive times

App stores typically want to avoid updating an app that is actively in use because this leads to the app's running processes being killed, which potentially interrupts what the user was doing.

Starting with Android 14, the InstallConstraints API gives installers a way to ensure that their app updates happen at an opportune moment. For example, an app store can call the commitSessionAfterInstallConstraintsAreMet() method to make sure that an update is only committed when the user is no longer interacting with the app in question.

Seamlessly install optional splits

With split APKs, features of an app can be delivered in separate APK files, rather than as a monolithic APK. Split APKs allow app stores to optimize the delivery of different app components. For example, app stores might optimize based on the properties of the target device. The PackageInstaller API has supported splits since its introduction in API level 22.

In Android 14, the setDontKillApp() method allows an installer to indicate that the app's running processes shouldn't be killed when new splits are installed. App stores can use this feature to seamlessly install new features of an app while the user is using the app.

应用元数据软件包

从 Android 14 开始,Android 软件包安装程序可让您指定应用元数据(例如数据安全做法),以在 Google Play 等应用商店页面上架。

检测用户何时截取设备屏幕截图

为了打造更加标准化的屏幕截图检测体验,Android 14 引入了可保护隐私的屏幕截图检测 API。借助此 API,应用可以按 activity 注册回调。如果用户在该 activity 可见时截取屏幕截图,系统会调用这些回调并通知用户。

用户体验

Sharesheet 自定义操作和经过改进的排名系统

Android 14 updates the system sharesheet to support custom app actions and more informative preview results for users.

Add custom actions

With Android 14, your app can add custom actions to the system sharesheet it invokes.

Screenshot of custom actions on the sharesheet.

Improve ranking of Direct Share targets

Android 14 uses more signals from apps to determine the ranking of the direct share targets to provide more helpful results for the user. To provide the most useful signal for ranking, follow the guidance for improving rankings of your Direct Share targets. Communication apps can also report shortcut usage for outgoing and incoming messages.

Direct Share row in the sharesheet, as shown by 1

支持内置和自定义预测性返回动画

视频:预测性返回动画

Android 13 在开发者选项背后引入了预测性“返回主屏幕”动画。在已启用开发者选项的受支持应用中使用时,滑回手势会显示动画,表明返回手势会使应用退回到主屏幕。

Android 14 包含针对“预测性返回”的多项改进和新指南:

在此 Android 14 预览版中,所有预测性返回功能都是位于开发者选项背后。请参阅与将您的应用迁移到预测性返回有关的开发者指南,以及与创建自定义应用内转换有关的开发者指南

大屏设备制造商按应用替换项

借助按应用替换项,设备制造商可以更改应用在大屏设备上的行为。例如,FORCE_RESIZE_APP 替换项指示系统调整应用大小以适应显示屏尺寸(避免尺寸兼容模式),即使在应用清单中设置了 resizeableActivity="false" 也是如此。

替换项旨在改善大屏设备上的用户体验。

新的清单属性可让您为应用停用某些设备制造商替换项。

大屏设备用户按应用替换项

按应用替换会更改应用在大屏设备上的行为。例如,无论应用的配置如何,OVERRIDE_MIN_ASPECT_RATIO_LARGE 设备制造商替换项都会将应用宽高比设置为 16:9。

Android 14 QPR1 允许用户在大屏设备上通过新的设置菜单应用按应用替换项。

分享应用界面

应用屏幕共享功能让用户能够在录制屏幕内容期间共享应用窗口,而非整个设备屏幕。

使用应用屏幕共享时,状态栏、导航栏、通知和其他系统界面元素会从共享显示屏中排除。系统只会分享所选应用的内容。

应用屏幕共享可让用户运行多个应用,但仅限单个应用共享内容,从而提高效率和隐私性。

Pixel 8 Pro 上的 Gboard 由 LLM 提供支持的智能回复

On Pixel 8 Pro devices with the December Feature Drop, developers can try out higher-quality smart replies in Gboard powered by on-device Large Language Models (LLMs) running on Google Tensor.

This feature is available as a limited preview for US English in WhatsApp, Line, and KakaoTalk. It requires using a Pixel 8 Pro device with Gboard as your keyboard.

To try it out, first enable the feature in Settings > Developer Options > AiCore Settings > Enable Aicore Persistent.

Next, open a conversation in a supported app to see LLM-powered Smart Reply in Gboard's suggestion strip in response to incoming messages.

Gboard utilizes on-device LLMs to provide higher-quality smart replies.

显卡

路径可查询和插值

Android's Path API is a powerful and flexible mechanism for creating and rendering vector graphics, with the ability to stroke or fill a path, construct a path from line segments or quadratic or cubic curves, perform boolean operations to get even more complex shapes, or all of these simultaneously. One limitation is the ability to find out what is actually in a Path object; the internals of the object are opaque to callers after creation.

To create a Path, you call methods such as moveTo(), lineTo(), and cubicTo() to add path segments. But there has been no way to ask that path what the segments are, so you must retain that information at creation time.

Starting in Android 14, you can query paths to find out what's inside of them. First, you need to get a PathIterator object using the Path.getPathIterator API:

Kotlin

val path = Path().apply {
    moveTo(1.0f, 1.0f)
    lineTo(2.0f, 2.0f)
    close()
}
val pathIterator = path.pathIterator

Java

Path path = new Path();
path.moveTo(1.0F, 1.0F);
path.lineTo(2.0F, 2.0F);
path.close();
PathIterator pathIterator = path.getPathIterator();

Next, you can call PathIterator to iterate through the segments one by one, retrieving all of the necessary data for each segment. This example uses PathIterator.Segment objects, which packages up the data for you:

Kotlin

for (segment in pathIterator) {
    println("segment: ${segment.verb}, ${segment.points}")
}

Java

while (pathIterator.hasNext()) {
    PathIterator.Segment segment = pathIterator.next();
    Log.i(LOG_TAG, "segment: " + segment.getVerb() + ", " + segment.getPoints());
}

PathIterator also has a non-allocating version of next() where you can pass in a buffer to hold the point data.

One of the important use cases of querying Path data is interpolation. For example, you might want to animate (or morph) between two different paths. To further simplify that use case, Android 14 also includes the interpolate() method on Path. Assuming the two paths have the same internal structure, the interpolate() method creates a new Path with that interpolated result. This example returns a path whose shape is halfway (a linear interpolation of .5) between path and otherPath:

Kotlin

val interpolatedResult = Path()
if (path.isInterpolatable(otherPath)) {
    path.interpolate(otherPath, .5f, interpolatedResult)
}

Java

Path interpolatedResult = new Path();
if (path.isInterpolatable(otherPath)) {
    path.interpolate(otherPath, 0.5F, interpolatedResult);
}

The Jetpack graphics-path library enables similar APIs for earlier versions of Android as well.

使用顶点和 fragment 着色器的自定义网格

Android has long supported drawing triangle meshes with custom shading, but the input mesh format has been limited to a few predefined attribute combinations. Android 14 adds support for custom meshes, which can be defined as triangles or triangle strips, and can, optionally, be indexed. These meshes are specified with custom attributes, vertex strides, varying, and vertex and fragment shaders written in AGSL.

The vertex shader defines the varyings, such as position and color, while the fragment shader can optionally define the color for the pixel, typically by using the varyings created by the vertex shader. If color is provided by the fragment shader, it is then blended with the current Paint color using the blend mode selected when drawing the mesh. Uniforms can be passed into the fragment and vertex shaders for additional flexibility.

适用于画布的硬件缓冲区渲染程序

To assist in using Android's Canvas API to draw with hardware acceleration into a HardwareBuffer, Android 14 introduces HardwareBufferRenderer. This API is particularly useful when your use case involves communication with the system compositor through SurfaceControl for low-latency drawing.