android - 无法在Android中使用MediaPlayer播放MediaStore.Audio歌曲

Question

我目前正在制作一个简单的音乐播放器，并且设法通过下面的示例脚本从媒体获取音乐列表。但是，问题是我不知道如何播放ContentResolver中的音乐。我读过http://developer.android.com/reference/android/provider/MediaStore.Audio.html，但很难理解。有好的样本或教程吗？我要实现的是从Android中的ContentResolver播放音乐。

   public  Track(Cursor cursor)
    {
        id              = cursor.getLong( cursor.getColumnIndex( MediaStore.Audio.Media._ID ));
        path            = cursor.getString( cursor.getColumnIndex(MediaStore.Audio.Media.DATA));
        title           = cursor.getString( cursor.getColumnIndex( MediaStore.Audio.Media.TITLE ));
        album           = cursor.getString( cursor.getColumnIndex( MediaStore.Audio.Media.ALBUM ));
        artist          = cursor.getString( cursor.getColumnIndex( MediaStore.Audio.Media.ARTIST ));
        albumId         = cursor.getLong( cursor.getColumnIndex( MediaStore.Audio.Media.ALBUM_ID ));
        artistId        = cursor.getLong( cursor.getColumnIndex( MediaStore.Audio.Media.ARTIST_ID ));
        duration        = cursor.getLong( cursor.getColumnIndex( MediaStore.Audio.Media.DURATION ));
        trackNo         = cursor.getInt( cursor.getColumnIndex( MediaStore.Audio.Media.TRACK ));
        uri             = ContentUris.withAppendedId(MediaStore.Audio.Media.EXTERNAL_CONTENT_URI, id);
    }

    public static List getItems(Context activity) {

        List tracks = new ArrayList();
        ContentResolver resolver = activity.getContentResolver();
        Cursor cursor = resolver.query(
                MediaStore.Audio.Media.EXTERNAL_CONTENT_URI,
                Track.COLUMNS,
                null,
                null,
                null
        );
        while( cursor.moveToNext() ){
            if( cursor.getLong(cursor.getColumnIndex( MediaStore.Audio.Media.DURATION)) < 3000 ){continue;}
            tracks.add(new Track(cursor));
        }
        cursor.close();
        return tracks;
    }

Answer 1

这是Google提供的文档，我引用:

Another feature that may be useful in a media player application is the ability to retrieve music that the user has on the device. You can do that by querying the ContentResolver for external media:

ContentResolver contentResolver = getContentResolver();
Uri uri = android.provider.MediaStore.Audio.Media.EXTERNAL_CONTENT_URI;
Cursor cursor = contentResolver.query(uri, null, null, null, null);
if (cursor == null) {
    // query failed, handle error.
} else if (!cursor.moveToFirst()) {
    // no media on the device
} else {
    int titleColumn = cursor.getColumnIndex(android.provider.MediaStore.Audio.Media.TITLE);
    int idColumn = cursor.getColumnIndex(android.provider.MediaStore.Audio.Media._ID);
    do {
       long thisId = cursor.getLong(idColumn);
       String thisTitle = cursor.getString(titleColumn);
       // ...process entry...
    } while (cursor.moveToNext());
}

To use this with the MediaPlayer, you can do this:

long id = /* retrieve it from somewhere */;
Uri contentUri = ContentUris.withAppendedId(
        android.provider.MediaStore.Audio.Media.EXTERNAL_CONTENT_URI, id);

mMediaPlayer = new MediaPlayer();
mMediaPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC);
mMediaPlayer.setDataSource(getApplicationContext(), contentUri);

// ...prepare and start...

资源:
Media Playback: Retrieving Media from a Content Resolver