MediaStore.Audio.Playlists.Members.moveItem有时无法工作

Question

我遇到了一个我自己不能处理的问题，我检查了每一行代码，但它仍然不起作用。

我有代表播放列表(普通MediaStore.Audio.Playlist)的draggable listener和用于改变歌曲顺序的drop listener。

listView.setDropListener(new DragSortListView.DropListener() {
                @Override
                public void drop(int i, int i2) {
                    if(playlistId != -1) {
                        boolean moved = MediaStore.Audio.Playlists.Members.moveItem(getContentResolver(), playlistId, i, i2);
                        System.out.println("Item moved " + moved);
                    }
                }
            });

我还有contentObserver，它可以处理游标的重新加载。

private class MyContentObserver extends ContentObserver {
    MyContentObserver(Handler handler) {
        super(handler);
    }
    @Override
    public boolean deliverSelfNotifications() {
        return true;
    }
    @Override
    public void onChange(boolean selfChange,  Uri uri) {
        super.onChange(selfChange);
        System.out.println("Updated");
    }
}

当然句柄是注册的

getContentResolver().registerContentObserver(Uri.parse("content://media"), true, contentObserver);

但这里有一个问题- moveItem总是返回true，但歌曲的顺序保持不变。在2.3.6的moveItem上完全不能工作，在4.4.2上--有时，在装有4.4.4的索尼平板电脑上--一切都运行得很好。我也尝试了这个代码，得到了相同的结果

public static final boolean moveItem(ContentResolver res,
                                     long playlistId, int from, int to) {
    Uri uri = MediaStore.Audio.Playlists.Members.getContentUri("external",
            playlistId)
            .buildUpon()
            .appendEncodedPath(String.valueOf(from))
            .appendQueryParameter("move", "true")
            .build();
    ContentValues values = new ContentValues();
    values.put(MediaStore.Audio.Playlists.Members.PLAY_ORDER, to);
    return res.update(uri, values, null, null) != 0;
}

Answer 1

我已经在我的播放列表细节上实现了拖放。大多数(如果不是全部来自这个论坛)if看起来比你的方法更复杂。也许下面的代码片段将帮助您在listview (播放列表上的曲目)的行上设置一个longclicklistener

private final class MyItemLongClickListener implements OnItemLongClickListener {
    public boolean onItemLongClick(AdapterView<?> arg0, View v,
                                   int row, long rowid) {
        if (android.os.Build.VERSION.SDK_INT > 10) {
            Cursor crs = (Cursor) mAdapter.getItem(row);
            int audio_id = crs.getInt(crs.getColumnIndex(MediaStore.Audio.Playlists.Members.AUDIO_ID));
            int _id = crs.getInt(crs.getColumnIndex(MediaStore.Audio.Playlists.Members._ID));
            int playorder_col = crs.getColumnIndexOrThrow(MediaStore.Audio.Playlists.Members.PLAY_ORDER);
            String playorder = crs.getString(playorder_col);
            String text = row + ":" + audio_id + ":" + lngplaylist_id + ":" +
                    playorder +
                    ":" + _id;
            ClipData.Item item = new ClipData.Item(text);
            ClipData dragData = new ClipData(text, new String[]{ClipDescription.MIMETYPE_TEXT_PLAIN, ClipDescription.MIMETYPE_TEXT_PLAIN}, item);
            dragData.addItem(new ClipData.Item(String.valueOf(row)));
            mListView.setOnDragListener(new MyDragListener());

            DragShadowBuilder shadowBuilder = new View.DragShadowBuilder(v);
            v.startDrag(dragData, //data to be dragged
                    shadowBuilder, //drag shadow
                    v, //local data about the drag and drop operation
                    0   //no needed flags
            );
            //            v.setVisibility(View.INVISIBLE);
            return true;
        }
        return false;
    }


  class MyDragListener implements OnDragListener {
    public int PositionOfDraggedItem = -1;
    public int PositionOfItemDraggedOver = -1;

    @Override
    public boolean onDrag(View v, DragEvent event) {
        int row = 0;
        switch (event.getAction()) {
            case DragEvent.ACTION_DRAG_STARTED:
                PositionOfDraggedItem = mListView.pointToPosition((int) (event.getX()), (int) event.getY());
                return true;
            case DragEvent.ACTION_DRAG_ENTERED:
                row = mListView.getPositionForView(mListView);
                return true;
            case DragEvent.ACTION_DRAG_LOCATION:
            case DragEvent.ACTION_DROP:

   and so on

Answer 2

public void drop(int i, int i2) {
    if(playlistId != -1) {
        boolean moved = MediaStore.Audio.Playlists.Members.moveItem(getContentResolver(), playlistId, i, i2);
        System.out.println("Item moved " + moved);

        // scan playlists
        String url = "file://" + Environment.getExternalStorageDirectory() + "/Playlists";
        Uri uri = Uri.parse(url);
        getActivity().sendBroadcast(new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE, uri));
    }
}