Android 6.0 - external storage files being deleted upon app uninstall

Question

My app uses the DownloadManager to download files to a subdirectory of the device's Music folder.

DownloadManager.Request request = new DownloadManager.Request(Uri.parse(url));
...
File file = new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_MUSIC) + "/MyStuff/song.mp3");
request.setDestinationUri(Uri.fromFile(file));

I have noticed that the files are being deleted when the app is uninstalled from a device running Marshmallow (this is not happening on older OS versions). Do you have any ideas about this?

Thanks

Answer 1

This is done by an internal class called DownloadReceiver and defined in the com.android.providers.downloads package manifest

<receiver android:name=".DownloadReceiver" android:exported="false">
    <intent-filter>
        <action android:name="android.intent.action.BOOT_COMPLETED" />
        <action android:name="android.net.conn.CONNECTIVITY_CHANGE" />
        <action android:name="android.intent.action.UID_REMOVED" />
    </intent-filter>
    <intent-filter>
        <action android:name="android.intent.action.MEDIA_MOUNTED" />
        <data android:scheme="file" />
    </intent-filter>
</receiver>

Here the android.intent.action.UID_REMOVED action catches the eye. It was introduced in Lollipop triggering a call to handleUidRemoved() performing

resolver.delete(ALL_DOWNLOADS_CONTENT_URI, Constants.UID + "=" + uid, null);