How to trigger MediaScan on Nexus 7?

问题

Because I want to make sure the MediaStore has the latest information without having to reboot I'd like to trigger the MediaScanner using the popular way I found on SO

context.sendBroadcast(new Intent(Intent.ACTION_MEDIA_MOUNTED,
                                 Uri.parse("file://" + Environment.getExternalStorageDirectory())));

This works fine on my Samsung S2 w/ICS but not on my Nexus 7 w/JellyBean. Logcat shows this on my Nexus 7:

WARN/ActivityManager(480): Permission denied: checkComponentPermission() owningUid=10014
WARN/BroadcastQueue(480): Permission Denial: broadcasting Intent { act=android.intent.action.MEDIA_MOUNTED dat=file:///storage/emulated/0 flg=0x10 } from com.example.foo.bar (pid=17488, uid=10046) is not exported from uid 10014 due to receiver com.android.providers.downloads/.DownloadReceiver
INFO/ActivityManager(480): Start proc com.google.android.music:main for broadcast com.google.android.music/.store.MediaStoreImportService$Receiver: pid=17858 uid=10038 gids={50038, 3003, 1015, 1028}
INFO/MusicStore(17858): Database version: 50
INFO/MediaStoreImporter(17858): Update: incremental Added music: 0 Updated music: 0 Deleted music: 0 Created playlists: 0 Updated playlists: 0 Deleted playlists: 0 Inserted playlist items: 0 Deleted playlist items: 0 Removed orphaned playlist items: 0

The last line sounds encouraging in theory, but the values are always 0 even after new files had been pushed to the SD card (via adb push). On my older device (S2) it does remount the SD card.

I've added the following permissions to my AndroidManifest.xml but it behaves the same as without those permissions:

<uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"/>
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>

Any ideas/alternatives?

---

Edit 1:

Note that I don't know any file paths of new or modified or deleted files. I just want to make sure the MediaStore is up-to-date.

回答1:

using the popular way I found on SO

Faking ACTION_MEDIA_MOUNTED broadcasts has never been an appropriate solution IMHO.

Any ideas/alternatives?

Use MediaScannerConnection, such as via its scanFile() static method.

回答2:

Here's the sample code based on CommonsWare's answer:

MediaScannerConnection.scanFile(activity, new String[]{path}, null,
                                new MediaScannerConnection.OnScanCompletedListener() {
    @Override
    public void onScanCompleted(final String path, final Uri uri) {
        Log.i(TAG, String.format("Scanned path %s -> URI = %s", path, uri.toString()));
    }
});

Even though in most of the cases, where one knows the files to be added/updated/etc. to the MediaStore, one should follow CommonsWare's answer, I wanted to post the my solution where I need to do it the rough way because I don't know the file paths. I use this mostly for testing/demoing:

Uri uri = Uri.fromFile(Environment.getExternalStorageDirectory());
activity.sendBroadcast(new Intent(Intent.ACTION_MEDIA_MOUNTED, uri));

BTW, no permissions are necessary for either solution.

回答3:

My answer is a little late, but it might help those, who save a new file, and would like to extend the media store by just that file on Android Kitkat: On Android Kitkat the intent ACTION_MEDIA_MOUNTED is blocked for non-system apps (I think, because scanning the whole filesystem is pretty expensive). But it is still possible to use the intent ACTION_MEDIA_SCANNER_SCAN_FILE to add a file to the media store:

File f = new File(path to the file you would like to add to the media store ...);
try {
    Intent mediaScanIntent = new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE);
    Uri uri = Uri.fromFile(f);
    mediaScanIntent.setData(uri);
    sendBroadcast(mediaScanIntent);
} catch(Exception e) {
    ... 
}

来源：https://stackoverflow.com/questions/15147536/how-to-trigger-mediascan-on-nexus-7