Question

如何优化使用ListView填充的Android中的CursorAdapter？我正在尝试创建一个MediaPlayer，列表会显示歌曲标题和专辑封面，但列表中的滚动速度非常慢。如何优化其中的List和recycle view？

好吧我在这里添加我的代码.....所以我让这个类扩展CursorAdapter然后我在类中创建了它的对象我希望它也填充它...然后我设置了一个类型对于每个类，并根据该类型填充特定版本。

public class PopulatingListAdapter extends CursorAdapter {

private final static int ALL_SONGS_TYPE = 0;
private final static int ALBUM_SONGS = 1;
private final static int ARTIST_SONGS = 2;
private final static int ALBUM_TYPE = 3;
private final static int ARTIST_TYPE = 4;

private final LayoutInflater myInflater;

private int typeOfList;

public void setType(int type){
    typeOfList=type;
}

View myView=null;

public PopulatingListAdapter(Context context, Cursor c, int flags) {
    super(context, c, flags);
    // TODO Auto-generated constructor stub
    myInflater = LayoutInflater.from(context);
}

public void initializingVariables(Activity activity){

}


@Override
public void bindView(View view, Context context, Cursor cursor) {
    // TODO Auto-generated method stub

    if(typeOfList==ALL_SONGS_TYPE)
    {   
        TextView songTitleNameAllSongs = (TextView) view.findViewById(R.id.all_song_title);
        songTitleNameAllSongs.setText(cursor.getString(cursor.getColumnIndex(MediaStore.Audio.Media.TITLE)));

        TextView songDisplayNameAllSongs = (TextView) view.findViewById(R.id.all_song_display);
        songDisplayNameAllSongs.setText(cursor.getString(cursor.getColumnIndex(MediaStore.Audio.Media.DISPLAY_NAME)));

        ImageView albumArtInAllSongs = (ImageView) view.findViewById(R.id.album_art_all_songs_single_row);
        Cursor myCursor;
        String[] projection = {MediaStore.Audio.Albums._ID,
                               MediaStore.Audio.Albums.ALBUM,
                               MediaStore.Audio.Albums.ALBUM_ART};
        myCursor = context.getContentResolver().query(MediaStore.Audio.Albums.EXTERNAL_CONTENT_URI, projection, null, null, null);
        int row=0;
        if(myCursor.moveToFirst())
        {
            while(row<myCursor.getCount())
          {

            if(cursor.getString(cursor.getColumnIndex(MediaStore.Audio.Media.ALBUM)).equals(myCursor.getString(myCursor.getColumnIndex(MediaStore.Audio.Albums.ALBUM))))
            {
            Bitmap bmp = BitmapFactory.decodeFile(myCursor.getString(myCursor.getColumnIndex(MediaStore.Audio.Albums.ALBUM_ART)));
            if(bmp!=null)
                albumArtInAllSongs.setImageBitmap(bmp);
            else
                albumArtInAllSongs.setImageDrawable(context.getResources().getDrawable(R.drawable.head_10));
            }
            myCursor.moveToPosition(++row);
          }
        }

    }else if(typeOfList==ALBUM_TYPE)
    {   
        TextView albumCoverTitleInAllAlbums = (TextView) view.findViewById(R.id.album_cover_title);
        albumCoverTitleInAllAlbums.setText(cursor.getString(cursor.getColumnIndex(MediaStore.Audio.Albums.ALBUM)));

        TextView artistAlbumTitleInAllAlbums = (TextView) view.findViewById(R.id.artist_album_title);
        artistAlbumTitleInAllAlbums.setText(cursor.getString(cursor.getColumnIndex(MediaStore.Audio.Albums.ARTIST)));

        ImageView albumArtInAllAlbum = (ImageView) view.findViewById(R.id.album_single_row_album_art);
        Bitmap bmp = BitmapFactory.decodeFile(cursor.getString(cursor.getColumnIndex(MediaStore.Audio.Albums.ALBUM_ART)));
        if(bmp!=null)
            albumArtInAllAlbum.setImageBitmap(bmp);
        else
            albumArtInAllAlbum.setImageDrawable(context.getResources().getDrawable(R.drawable.head_10));        
    }else if(typeOfList==ARTIST_TYPE)
    {   
        TextView artistNameInAllArtist = (TextView) view.findViewById(R.id.artists_single_name);
        artistNameInAllArtist.setText(cursor.getString(cursor.getColumnIndex(MediaStore.Audio.Artists.ARTIST)));

    }else if(typeOfList==ALBUM_SONGS)
    {   
        TextView albumSongTitleNameInAlbumSongs = (TextView) view.findViewById(R.id.albums_songs_name_of_song);
        albumSongTitleNameInAlbumSongs.setText(cursor.getString(cursor.getColumnIndex(MediaStore.Audio.Media.TITLE)));

        TextView albumSongDisplayNameInAlbumSongs = (TextView) view.findViewById(R.id.albums_songs_name_of_album);
        albumSongDisplayNameInAlbumSongs.setText(cursor.getString(cursor.getColumnIndex(MediaStore.Audio.Media.ALBUM)));
    }else if(typeOfList==ARTIST_SONGS){
        TextView artistSongTitleNameInArtistSongs = (TextView) view.findViewById(R.id.artist_song_title_name);
        artistSongTitleNameInArtistSongs.setText(cursor.getString(cursor.getColumnIndex(MediaStore.Audio.Media.TITLE)));

        TextView artistSongDisplayNameInArtistSongs = (TextView) view.findViewById(R.id.artist_song_artist_name);
        artistSongDisplayNameInArtistSongs.setText(cursor.getString(cursor.getColumnIndex(MediaStore.Audio.Media.ARTIST)));
    }
  }


@Override
public View newView(Context context, Cursor cursor, ViewGroup parent) {
    // TODO Auto-generated method stub
        if(typeOfList==ALL_SONGS_TYPE)
        {
            myView = myInflater.inflate(R.layout.all_songs_single_row, parent, false);
        }else if(typeOfList==ALBUM_TYPE)
        {
            myView = myInflater.inflate(R.layout.album_single_row, parent, false);
        }else if(typeOfList==ARTIST_TYPE)
        {
            myView = myInflater.inflate(R.layout.artists_single_row, parent, false);
        }else if(typeOfList==ALBUM_SONGS)
        {
            myView = myInflater.inflate(R.layout.albums_songs_single_row, parent, false);
        }else if(typeOfList==ARTIST_SONGS)
        {
            myView = myInflater.inflate(R.layout.artists_song_single_row, parent, false);
        }
    return myView;
}

Answer 1

看起来你在主（UI）线程上进行了大量的图像和音频文件下载。为了提高性能，应该在后台线程上下载大文件，这样它们不会减慢用户界面的速度。当后台线程完成其任务时，您需要一种机制让它们通知您的活动并传递加载的数据。有几种方法可以实现这一目标，但完整的描述对于这个论坛来说太长了。

以下是一些有助于后台加载的研究课程：
Loader
AsyncTask

请查看这些教程以获取更多信息：
Processing Bitmaps Off the UI Thread
Loading Data in the Background

使用CursorAdapter在Android中优化ListView？

1 个答案: