Question

我没有得到任何答案，所以我决定重新编辑

我正在使用这个类在android中创建音乐播放列表。我从here获得了代码代码：

public static final String TAG = "MediaUtil";

public static void deleteTrack(Context context, String localPath) {
    Uri uri = MediaStore.Audio.Media.getContentUriForPath(localPath);
    context.getContentResolver().delete(uri, null, null);
}

public static Cursor query(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;
    }
}

public static Cursor query(Context context, Uri uri, String[] projection,
                           String selection, String[] selectionArgs, String sortOrder) {
    return query(context, uri, projection, selection, selectionArgs, sortOrder, 0);
}

private static int intFromCursor(Cursor c) {
    int id = -1;
    if (c != null) {
        c.moveToFirst();
        if (!c.isAfterLast()) {
            id = c.getInt(0);
        }
    }
    c.close();
    return id;
}

public static int idForplaylist(Context context, String name) {
    Cursor c = query(context, MediaStore.Audio.Playlists.EXTERNAL_CONTENT_URI,
            new String[] { MediaStore.Audio.Playlists._ID },
            MediaStore.Audio.Playlists.NAME + "=?",
            new String[] { name },
            MediaStore.Audio.Playlists.NAME);
    return intFromCursor(c);
}

public static int idFortrack(Context context, String path) {
    Cursor c = query(context, MediaStore.Audio.Playlists.EXTERNAL_CONTENT_URI,
            new String[] { MediaStore.Audio.Media._ID },
            MediaStore.Audio.Media.DATA + "=?",
            new String[] { path },
            MediaStore.Audio.Media.DATA);
    return intFromCursor(c);
}

public static void writePlaylist(Context context, String playlistName, ArrayList<String> paths) {
    try{
        ContentResolver resolver = context.getContentResolver();
        int playlistId = idForplaylist(context, playlistName);
        Uri uri;
        if (playlistId == -1) {
            ContentValues values = new ContentValues(1);
            values.put(MediaStore.Audio.Playlists.NAME, playlistName);
            uri = resolver.insert(MediaStore.Audio.Playlists.EXTERNAL_CONTENT_URI, values);
            playlistId = idForplaylist(context, playlistName);
        } else {
            uri = MediaStore.Audio.Playlists.Members.getContentUri("external", playlistId);
        }
        Log.d(TAG, String.format("Writing playlist %s", uri));

        // Delete everything from the old playlist
        context.getContentResolver().delete(uri, null, null);

        // Add all the new tracks to the playlist.
        int size = paths.size();
        ContentValues values [] = new ContentValues[size];
        for (int k = 0; k < size; ++k) {
            values[k] = new ContentValues();
            values[k].put(MediaStore.Audio.Playlists.Members.PLAY_ORDER, k);
            values[k].put(MediaStore.Audio.Playlists.Members.AUDIO_ID, idFortrack(context, paths.get(k)));
        }

        resolver.bulkInsert(uri, values);
    }
    catch (Exception e){
        Log.e("Mediautil",e.getMessage());
    }

}

` 以下是我的明确权限：

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.WRITE_INTERNAL_STORAGE" />
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />

写完播放列表后，我会收到此日志：

D/MediaUtil: Writing playlist content://media/external/audio/playlists/33813

但我无法看到任何音乐播放器中的播放列表。我做错了什么？

为什么创建播放列表在Android上不可见？

0 个答案: