照片选择器

照片选择器对话框中会显示设备上的媒体文件。您可选择要与应用分享的照片。
图 1.照片选择器提供了一个直观的界面，方便您与应用分享照片。

照片选择器提供了一个可浏览的界面，其中按日期（从最近到最早）顺序向用户呈现其媒体库中的文件。如隐私保护最佳实践 Codelab 中所示，照片选择器为用户提供了一种安全的内置授权方式，让用户可以仅向应用授予对所选图片和视频的访问权限，而不是对整个媒体库的访问权限。

如果用户的设备上有符合条件的云媒体服务提供商，则还可以： 从远程存储的照片和视频中选择。详细了解云媒体 提供商。

该工具会自动更新，让应用用户能够长期使用扩展的功能，而无需更改任何代码。

使用 Jetpack activity 协定

为了简化照片选择器的集成，请添加 1.7.0 版或更高版本的 androidx.activity 库。

您可以使用以下 activity 结果协定来启动照片选择器：

如果照片选择器在设备上不可用，该库会自动调用 ACTION_OPEN_DOCUMENT intent 操作。搭载 Android 4.4（API 级别 19）或更高版本的设备支持此 intent。您可以通过调用 isPhotoPickerAvailable() 来验证照片选择器在给定设备上是否可用。

选择单个媒体文件

如需选择单个媒体文件，请使用 PickVisualMedia activity 结果协定，如以下代码段所示：

Kotlin

// Registers a photo picker activity launcher in single-select mode.
val pickMedia = registerForActivityResult(PickVisualMedia()) { uri ->
    // Callback is invoked after the user selects a media item or closes the
    // photo picker.
    if (uri != null) {
        Log.d("PhotoPicker", "Selected URI: $uri")
    } else {
        Log.d("PhotoPicker", "No media selected")
    }
}

// Include only one of the following calls to launch(), depending on the types
// of media that you want to let the user choose from.

// Launch the photo picker and let the user choose images and videos.
pickMedia.launch(PickVisualMediaRequest(PickVisualMedia.ImageAndVideo))

// Launch the photo picker and let the user choose only images.
pickMedia.launch(PickVisualMediaRequest(PickVisualMedia.ImageOnly))

// Launch the photo picker and let the user choose only videos.
pickMedia.launch(PickVisualMediaRequest(PickVisualMedia.VideoOnly))

// Launch the photo picker and let the user choose only images/videos of a
// specific MIME type, such as GIFs.
val mimeType = "image/gif"
pickMedia.launch(PickVisualMediaRequest(PickVisualMedia.SingleMimeType(mimeType)))

Java

// Registers a photo picker activity launcher in single-select mode.
ActivityResultLauncher<PickVisualMediaRequest> pickMedia =
        registerForActivityResult(new PickVisualMedia(), uri -> {
    // Callback is invoked after the user selects a media item or closes the
    // photo picker.
    if (uri != null) {
        Log.d("PhotoPicker", "Selected URI: " + uri);
    } else {
        Log.d("PhotoPicker", "No media selected");
    }
});

// Include only one of the following calls to launch(), depending on the types
// of media that you want to let the user choose from.

// Launch the photo picker and let the user choose images and videos.
pickMedia.launch(new PickVisualMediaRequest.Builder()
        .setMediaType(PickVisualMedia.ImageAndVideo.INSTANCE)
        .build());

// Launch the photo picker and let the user choose only images.
pickMedia.launch(new PickVisualMediaRequest.Builder()
        .setMediaType(PickVisualMedia.ImageOnly.INSTANCE)
        .build());

// Launch the photo picker and let the user choose only videos.
pickMedia.launch(new PickVisualMediaRequest.Builder()
        .setMediaType(PickVisualMedia.VideoOnly.INSTANCE)
        .build());

// Launch the photo picker and let the user choose only images/videos of a
// specific MIME type, such as GIFs.
String mimeType = "image/gif";
pickMedia.launch(new PickVisualMediaRequest.Builder()
        .setMediaType(new PickVisualMedia.SingleMimeType(mimeType))
        .build());

选择多个媒体项

如需选择多个媒体项，请设置可选媒体文件数量上限，如以下代码段所示。

Kotlin

// Registers a photo picker activity launcher in multi-select mode.
// In this example, the app lets the user select up to 5 media files.
val pickMultipleMedia =
        registerForActivityResult(PickMultipleVisualMedia(5)) { uris ->
    // Callback is invoked after the user selects media items or closes the
    // photo picker.
    if (uris.isNotEmpty()) {
        Log.d("PhotoPicker", "Number of items selected: ${uris.size}")
    } else {
        Log.d("PhotoPicker", "No media selected")
    }
}

// For this example, launch the photo picker and let the user choose images
// and videos. If you want the user to select a specific type of media file,
// use the overloaded versions of launch(), as shown in the section about how
// to select a single media item.
pickMultipleMedia.launch(PickVisualMediaRequest(PickVisualMedia.ImageAndVideo))

Java

// Registers a photo picker activity launcher in multi-select mode.
// In this example, the app lets the user select up to 5 media files.
ActivityResultLauncher<PickVisualMediaRequest> pickMultipleMedia =
        registerForActivityResult(new PickMultipleVisualMedia(5), uris -> {
    // Callback is invoked after the user selects media items or closes the
    // photo picker.
    if (!uris.isEmpty()) {
        Log.d("PhotoPicker", "Number of items selected: " + uris.size());
    } else {
        Log.d("PhotoPicker", "No media selected");
    }
});

// For this example, launch the photo picker and let the user choose images
// and videos. If you want the user to select a specific type of media file,
// use the overloaded versions of launch(), as shown in the section about how
// to select a single media item.
pickMultipleMedia.launch(new PickVisualMediaRequest.Builder()
        .setMediaType(PickVisualMedia.ImageAndVideo.INSTANCE)
        .build());

平台会限制您可以让用户在照片选择器中选择的文件数量上限。如需访问此限制，请调用 getPickImagesMaxLimit()。 在不支持照片选择器的设备上，系统会忽略此上限。

适用的设备

照片选择器适用于符合以下条件的设备：

搭载 Android 4.4（API 级别 19）到 Android 10（API 级别 29）的旧款设备，以及搭载 Android 11 或 12 且支持 Google Play 服务的 Android Go 设备，都可以安装向后移植的照片选择器版本。如需通过 Google Play 服务自动安装向后移植的照片选择器模块，请将以下条目添加到应用清单文件的 <application> 标记中：

<!-- Trigger Google Play services to install the backported photo picker module. -->
<service android:name="com.google.android.gms.metadata.ModuleDependencies"
         android:enabled="false"
         android:exported="false"
         tools:ignore="MissingClass">
    <intent-filter>
        <action android:name="com.google.android.gms.metadata.MODULE_DEPENDENCIES" />
    </intent-filter>
    <meta-data android:name="photopicker_activity:0:required" android:value="" />
</service>

保留媒体文件访问权限

默认情况下，系统会授予应用对媒体文件的访问权限，直到设备重启或应用停止运行。如果您的应用执行长时间运行的工作（例如在后台上传大型文件），您可能需要将此访问权限保留更长时间。为此，请调用 takePersistableUriPermission() 方法：

Kotlin

val flag = Intent.FLAG_GRANT_READ_URI_PERMISSION
context.contentResolver.takePersistableUriPermission(uri, flag)

Java

int flag = Intent.FLAG_GRANT_READ_URI_PERMISSION;
context.contentResolver.takePersistableUriPermission(uri, flag);