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

用户可通过地区偏好设置对温度单位、一周的第一天和编号系统进行个性化设置。居住在美国的欧洲用户可能更希望使用摄氏度,而不是华氏度,并且希望应用将星期一视为一周的开始,而不是像美国那样默认从星期日开始。

新 Android 设置菜单包含这些偏好设置,使用户能够在一个位置集中发现这些应用更改偏好设置。这些偏好设置在备份和恢复设备后也会保持不变。多个 API 和 intent(例如 getTemperatureUnitgetFirstDayOfWeek)会为您的应用授予读取权限来访问用户偏好设置,因此您的应用可以调整其显示信息的方式。您还可以在 ACTION_LOCALE_CHANGED 上注册 BroadcastReceiver,以便在地区偏好设置发生更改时处理语言区域配置更改。

如需找到这些设置,请打开“设置”应用,然后依次前往系统 > 语言和输入法 > 地区偏好设置

Android 系统设置中的地区偏好设置屏幕。
Android 系统设置中的地区偏好设置温度选项。

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

An illustration of Standard Dynamic Range (SDR) versus High Dynamic Range (HDR) image quality.

Android 14 adds support for High Dynamic Range (HDR) images that retain more of the information from the sensor when taking a photo, which enables vibrant colors and greater contrast. Android uses the Ultra HDR format, which is fully backward compatible with JPEG images, allowing apps to seamlessly interoperate with HDR images, displaying them in Standard Dynamic Range (SDR) as needed.

Rendering these images in the UI in HDR is done automatically by the framework when your app opts in to using HDR UI for its Activity Window, either through a manifest entry or at runtime by calling Window.setColorMode(). You can also capture compressed Ultra HDR still images on supported devices. With more colors recovered from the sensor, editing in post can be more flexible. The Gainmap associated with Ultra HDR images can be used to render them using OpenGL or Vulkan.

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 gains support for lossless audio formats for audiophile-level experiences over USB wired headsets. You can query a USB device for its preferred mixer attributes, register a listener for changes in preferred mixer attributes, and configure mixer attributes using the AudioMixerAttributes class. This class represents the format, such as channel mask, sample rate, and behavior of the audio mixer. The class allows for audio to be sent directly, without mixing, volume adjustment, or processing effects.

开发者工作效率和工具

Credential Manager

Android 14 adds Credential Manager as a platform API, with additional support back to Android 4.4 (API level 19) devices through a Jetpack Library using Google Play services. Credential Manager aims to make sign-in easier for users with APIs that retrieve and store credentials with user-configured credential providers. Credential Manager supports multiple sign-in methods, including username and password, passkeys, and federated sign-in solutions (such as Sign-in with Google) in a single API.

Passkeys provide many advantages. For example, passkeys are built on industry standards, can work across different operating systems and browser ecosystems, and can be used with both websites and apps.

For more information, see the Credential Manager and passkeys documentation and the blogpost about Credential Manager and passkeys.

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 将继续更新 Android 的核心库,以与最新 OpenJDK LTS 版本中的功能保持一致,包括适合应用和平台开发者的库更新和 Java 17 语言支持。

其中包含以下功能和改进:

  • 将大约 300 个 java.base 类更新为支持 Java 17。
  • 文本块 - 为 Java 编程语言引入了多行字符串字面量。
  • instanceof 模式匹配:可让对象在 instanceof 中被视为具有特定类型,而无需任何额外的变量。
  • 密封类:允许您限制哪些类和接口可以扩展或实现它们。

得益于 Google Play 系统更新 (Project Mainline),6 亿多台设备能够接收包含这些更改的最新 Android 运行时 (ART) 更新。我们致力于为应用提供更加一致、安全的跨设备环境,并为用户提供独立于平台版本的新功能。

Java 和 OpenJDK 是 Oracle 及/或其关联公司的商标或注册商标。

针对应用商店的改进

Android 14 引入了多个 PackageInstaller API,可帮助应用商店改善其用户体验。

下载之前请求批准安装

安装或更新应用可能需要用户批准。 例如,当使用 REQUEST_INSTALL_PACKAGES 权限的安装程序尝试安装新应用时。在之前的 Android 版本中,应用商店只有在 APK 写入安装会话且该会话已提交之后才能请求用户批准。

从 Android 14 开始,requestUserPreapproval() 方法可让安装程序在提交安装会话之前请求用户批准。此项改进可让应用商店将任何 APK 的下载操作推迟到用户批准安装之后。此外,用户批准安装后,应用商店可以在后台下载并安装应用,而不会干扰用户。

承担未来更新的责任

通过 setRequestUpdateOwnership() 方法,安装程序可以告知系统它打算负责未来安装的应用更新。此功能可实现更新所有权强制执行,即只有更新所有者才能为应用安装自动更新。更新所有权强制执行有助于确保用户仅从预期的应用商店接收更新。

任何其他安装程序(包括使用 INSTALL_PACKAGES 权限的安装程序)都必须获得用户的明确批准,才能安装更新。如果用户决定继续从其他来源进行更新,更新所有权将会丢失。

在干扰较少的时段更新应用

应用商店通常希望避免更新正在使用的应用,因为这会导致应用正在运行的进程被终止,而这可能会中断用户正在执行的操作。

从 Android 14 开始,InstallConstraints API 让安装程序可以确保其应用更新在适当的时机进行。例如,应用商店可以调用 commitSessionAfterInstallConstraintsAreMet() 方法来确保仅在用户不再与相关应用互动时进行更新。

无缝安装可选拆分

借助拆分 APK,应用的功能可以通过单独的 APK 文件提供,而不是以单体式 APK 的形式提供。借助拆分 APK,应用商店可以优化不同应用组件的提供。例如,应用商店可能会根据目标设备的属性进行优化。自从在 API 级别 22 中引入以来,PackageInstaller API 一直支持拆分。

在 Android 14 中,setDontKillApp() 方法可让安装程序指明在安装新的分块时不应终止应用正在运行的进程。应用商店可以使用此功能,在用户使用应用时无缝安装应用的新功能。

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

Video: Predictive back animations

Android 13 introduced the predictive back-to-home animation behind a developer option. When used in a supported app with the developer option enabled, swiping back shows an animation indicating that the back gesture exits the app back to the home screen.

Android 14 includes multiple improvements and new guidance for Predictive Back:

With this Android 14 preview release, all features of Predictive Back remain behind a developer option. See the developer guide to migrate your app to predictive back, as well as the developer guide to creating custom in-app transitions.

大屏设备制造商按应用替换项

Per-app overrides enable device manufacturers to change the behavior of apps on large screen devices. For example, the FORCE_RESIZE_APP override instructs the system to resize the app to fit display dimensions (avoiding size compatibility mode) even if resizeableActivity="false" is set in the app manifest.

Overrides are intended to improve the user experience on large screens.

New manifest properties enable you to disable some device manufacturer overrides for your app.

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。

局部屏幕共享

部分屏幕共享功能可让用户在屏幕内容录制期间共享应用窗口,而非整个设备屏幕。

使用局部屏幕共享时,状态栏、导航栏、通知和其他系统界面元素将从共享显示中排除。系统只会分享所选应用的内容。

局部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,从而提高工作效率和隐私性。

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

为了帮助使用 Android 的 Canvas API 通过硬件加速绘制 HardwareBuffer,Android 14 引入了 HardwareBufferRenderer。当您的用例需要通过 SurfaceControl 与系统合成器进行通信以实现低延迟绘制时,此 API 特别有用。