在Android中使用CursorAdapter優化ListView？

Question

如何優化ListView的Android正在填充使用CursorAdapter？我正嘗試創建一個MediaPlayer，該列表隨歌曲標題和專輯封面出現，但列表中的滾動非常緩慢。 如何優化List和recycle view呢？

好的，我在這裏添加我的代碼.....所以我讓這個類擴展了CursorAdapter，然後我在類中創建了它的對象，我也想讓它填充它......然後我爲每個類設置一個類型並根據該類型填充特定版本。

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

它看起來像你在主（UI）線程上大量下載圖像和音頻文件。爲了提高性能，應該在後臺線程上下載大文件，以便它們不會減慢用戶界面的速度。當後臺線程完成其任務時，您需要一種機制讓他們通知您的活動並傳遞加載的數據。有幾種方法可以做到這一點，但對於這個論壇來說，完整的描述太長了。

下面是一些類的研究，可與後臺加載幫助：
Loader
AsyncTask

請看看這些教程以獲取更多信息：
Processing Bitmaps Off the UI Thread
Loading Data in the Background