Android MediaPlayer无法设置uri

Question

I'm trying to store the uri of a previously played song, using sharedPreferences. But when if fetch and reconstruct the uri in order to play the song i get the following error message:

05-03 20:43:14.642 8617-8716/com.stopwatch.app W/MediaPlayer: Couldn't open file on client side; trying server side: java.lang.SecurityException: Permission Denial: opening provider com.android.providers.media.MediaDocumentsProvider from ProcessRecord{2c95b0 8617:com.stopwatch.app/u0a175} (pid=8617, uid=10175) requires android.permission.MANAGE_DOCUMENTS or android.permission.MANAGE_DOCUMENTS

05-03 20:43:14.658 8617-8716/com.stopwatch.app I/MediaPlayer: setDataSource(content://com.android.providers.media.documents/document/audio%3A18504)

05-03 20:43:14.661 8617-8716/com.stopwatch.app E/MediaPlayer: Unable to create media player

05-03 20:43:14.662 8617-8716/com.stopwatch.app W/System.err: java.io.IOException: setDataSource failed.: status=0x80000000

I don't get way I would need android.permission.MANAGE_DOCUMENTS and my IDE tell me that it is a permission only suited for system applications. My code looks like this:

if(prefs.contains("AudioFile")){
        try {
            String UriString = prefs.getString("AudioFile", null);
            Uri uri = Uri.parse(UriString);
            mediaPlayer.setDataSource(this, uri);
            Gdx.app.log("Android Media Player", "Successfully got data");
        } catch (IOException e) {
            e.printStackTrace();
            Gdx.app.log("Android Media Player", e.getMessage());
        }
        try {
            mediaPlayer.prepare();
            Gdx.app.log("Android Media Player", "Successfully prepared content");
        } catch (IOException e) {
            e.printStackTrace();
            Gdx.app.log("Android Media Player", e.getMessage());
        }
    }

I have tried running it in the onCreate method (which seems to be a bad idea) and through another method which is called on a button click, both failed.

Notice that if I start the application and retrieve the uri through an intent at initiate the mediaPlayer through:

protected void onActivityResult (int requestCode, int resultCode, Intent data){
    if(requestCode == MUSIC_REQUEST){
        if(resultCode == RESULT_OK){
            Uri myUri = data.getData();
            SharedPreferences.Editor editor = prefs.edit();
            editor.putString("AudioFile", myUri.toString());
            editor.commit();
            System.out.println(myUri);
            try {
                mediaPlayer.setDataSource(this, myUri);
                Gdx.app.log("Android Media Player", "Succesfully got data");
            } catch (IOException e) {
                e.printStackTrace();
                Gdx.app.log("Android Media Player", e.getMessage());
            }
            try {
                mediaPlayer.prepare();
                Gdx.app.log("Android Media Player", "Succesfully prepared content");
            } catch (IOException e) {
                e.printStackTrace();
                Gdx.app.log("Android Media Player", e.getMessage());
            }
        }
    }
    super.onActivityResult(requestCode, resultCode, data);
}

I have no problems, not even if I substitute with mediaPlayer.setDataSource(this, Uri.parse(myUri.toString)).

Answer 1

You cannot persist a Uri value and expect it to work later. Those that have a content scheme offer you access to the content for a very short time .

If you are using ACTION_OPEN_DOCUMENT to get your Uri , you can request long-term access to the content via takePersistableUriPermission() on a ContentResolver . You will still have to deal with the possibility that the user might move or delete the content, though.

If you are using ACTION_GET_CONTENT to get your Uri , either switch to ACTION_OPEN_DOCUMENT (if your minSdkVersion is 19 or higher) or make a copy of the content, then use your copy.