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谁能帮我查询Android DB。我需要选择所选文件夹中的所有专辑。对于我制作的所有歌曲：

  private Cursor allSongs() {
    String[] projection = {MediaStore.Audio.Media._ID,             // 0
            MediaStore.Audio.Media.ARTIST,          // 1
            MediaStore.Audio.Media.TITLE,           // 2
            MediaStore.Audio.Media.ALBUM_ID,  // 3
            MediaStore.Audio.Media.ALBUM,           // 4
            MediaStore.Audio.Media.DATA,            // 5
            MediaStore.Audio.Media.DISPLAY_NAME,    // 6
            MediaStore.Audio.Media.DURATION,     //7
            MediaStore.Audio.Media.TITLE_KEY        //8
    };

    String selection = android.provider.MediaStore.Audio.Media.DATA + " like ? ";
    String MEDIA_PATH = Environment.getExternalStorageDirectory() + "/Music/";

    Cursor musicListSDCardCursor = mQuery(
            getActivity(),
            MediaStore.Audio.Media.EXTERNAL_CONTENT_URI,
            projection, selection, new String[]{"%" + MEDIA_PATH + "%"}, null, 0);
    return musicListSDCardCursor;
}

和 mQuery 代码：

 public static Cursor mQuery(Context context, Uri uri, String[] projection,
                            String selection, String[] selectionArgs, String sortOrder, int limit) {
    try {
        ContentResolver resolver = context.getContentResolver();
        if (resolver == null) {
            return null;
        }
        if (limit > 0) {
            uri = uri.buildUpon().appendQueryParameter("limit", "" + limit).build();
        }
        return resolver.query(uri, projection, selection, selectionArgs, sortOrder);
    } catch (UnsupportedOperationException ex) {
        return null;
    }

}

但是如何查询 MediaStore 以从该文件夹 /sdcard/Music/ 获取所有专辑？

我做到了，比如：

 private Cursor allAlbums() {
    Cursor cursor_albums_from_songs = allSongs();

    HashSet<String> albumsList = new HashSet<String>();
    int count = cursor_albums_from_songs.getCount();
    for (int i = 0; i < count; i++) {
        cursor_albums_from_songs.moveToPosition(i);
        albumsList.add(cursor_albums_from_songs.getString(3));
        Log.i("cursor", "" + cursor_albums_from_songs.getString(3));
    }
    Log.i("allAlbums", "" + albumsList.size());
    ArrayList<String> list = new ArrayList<String>(albumsList.size());
    list.addAll(albumsList);
    int count_ids = list.size();
    Cursor[] cursors = new Cursor[count_ids];
    for (int i = 0; i < count_ids; i++) {
        String selection = MediaStore.Audio.Albums._ID + " = ? ";
        String[] selectionArgs = new String[]{list.get(i)};

        String[] projection = {MediaStore.Audio.Albums._ID,  //0
                MediaStore.Audio.Albums.ALBUM,               // 1
                MediaStore.Audio.Albums.ALBUM_ART,           // 2
                MediaStore.Audio.Albums.ARTIST,              //3
                MediaStore.Audio.Albums.FIRST_YEAR,           //4
                MediaStore.Audio.Albums.NUMBER_OF_SONGS      //5
        };

        Cursor artistListSDCardCursor = mQuery(
                mContext,
                MediaStore.Audio.Albums.EXTERNAL_CONTENT_URI,
                projection, selection, selectionArgs, null, 0);
        cursors[i] = artistListSDCardCursor;
    }
    MergeCursor mMergeCursor = new MergeCursor(cursors);
    return mMergeCursor;
}
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