官方解释

https://developer.android.com/reference/android/app/backup/BackupManager.html

The interface through which an application interacts with the Android backup service to request backup and restore operations. Applications instantiate it using the constructor and issue calls through that instance.

When an application has made changes to data which should be backed up, a call to dataChanged() will notify the backup service. The system will then schedule a backup operation to occur in the near future. Repeated calls to dataChanged() have no further effect until the backup operation actually occurs.

A backup or restore operation for your application begins when the system launches the BackupAgent subclass you’ve declared in your manifest. See the documentation for BackupAgent for a detailed description of how the operation then proceeds.Several attributes affecting the operation of the backup and restore mechanism can be set on the
tag in your application’s AndroidManifest.xml file.

直译过来就是：这个接口能实现应用程序通过Andorid备份服务请求备份和恢复的操作

Attributes

android:allowBackup 是否允许应用程序进行备份
android:backupAgent
android:killAfterRestore
android:restoreAnyVersion