Android：列出所有录制的文件

Question

我想获取默认录音机录制的所有声音的arraylist。这怎么可能？我使用以下代码从sdcard获取所有声音，但它根本不包含录制的声音，它们具有3ga扩展名。

String selection = MediaStore.Audio.Media.IS_MUSIC + " != 0";
String[] projection = {
  MediaStore.Audio.Media._ID,
  MediaStore.Audio.Media.ARTIST,
  MediaStore.Audio.Media.TITLE,
  MediaStore.Audio.Media.DATA,
  MediaStore.Audio.Media.DISPLAY_NAME,
  MediaStore.Audio.Media.DURATION
};
Cursor cursor = ((Activity) ctx).managedQuery(
  MediaStore.Audio.Media.EXTERNAL_CONTENT_URI,
  projection,
  selection,
  null,
  null
);
if(cursor != null) {
  while(cursor.moveToNext()){
    songs.add(new Song(cursor.getString(0), cursor.getString(4)));
  }
}