我試圖顯示設備上找到的歌曲列表直接從MediaStore請求數據。我正在使用RecyclerView
和使用CursorAdapter
從MediaStore獲取數據的適配器。 當調用適配器的onBindViewHolder
時,請求被傳遞給CursorAdapter
的bindView
函數,設置所有可視元素。圖片閃爍時滾動在RecyclerView
public class ListRecyclerAdapter3 extends RecyclerView.Adapter<ListRecyclerAdapter3.SongViewHolder> {
// PATCH: Because RecyclerView.Adapter in its current form doesn't natively support
// cursors, we "wrap" a CursorAdapter that will do all teh job
// for us
public MediaStoreHelper mediaStoreHelper;
CustomCursorAdapter mCursorAdapter;
Context mContext;
public class SongViewHolder extends RecyclerView.ViewHolder {
public TextView textItemTitle;
public TextView textItemSub;
public ImageView imgArt;
public int position;
public String album_id;
public String path_art;
public String path_file;
public SongViewHolder(View v) {
super(v);
textItemTitle = (TextView) v.findViewById(R.id.textItemTitle);
textItemSub = (TextView) v.findViewById(R.id.textItemSub);
imgArt = (ImageView) v.findViewById(R.id.imgArt);
}
}
private class CustomCursorAdapter extends CursorAdapter {
public CustomCursorAdapter(Context context, Cursor c, int flags) {
super(context, c, flags);
}
@Override
public View newView(final Context context, Cursor cursor, ViewGroup parent) {
View v = LayoutInflater.from(parent.getContext())
.inflate(R.layout.song_item, parent, false);
final SongViewHolder holder = new SongViewHolder(v);
v.setTag(holder);
return v;
}
@Override
public void bindView(View view, Context context, Cursor cursor) {
SongViewHolder holder = (SongViewHolder) view.getTag();
holder.position = cursor.getPosition();
holder.textItemTitle.setText(cursor.getString(cursor.getColumnIndex("title")));
holder.textItemSub.setText(cursor.getString(cursor.getColumnIndex("artist")));
holder.album_id = cursor.getString(cursor.getColumnIndex("album_id"));
holder.path_file = cursor.getString(cursor.getColumnIndex("_data"));
Picasso.with(holder.imgArt.getContext())
.cancelRequest(holder.imgArt);
holder.imgArt.setImageDrawable(null);
new DownloadImageTask(mediaStoreHelper, context, holder.imgArt).execute(holder.album_id);
}
}
private class DownloadImageTask extends AsyncTask<String, String, String> {
private MediaStoreHelper mediaStoreHelper;
private ImageView imageView;
private Context context;
public DownloadImageTask(MediaStoreHelper mediaStoreHelper, Context context, ImageView imageView)
{
this.mediaStoreHelper = mediaStoreHelper;
this.context = context;
this.imageView = imageView;
}
@Override
protected String doInBackground(String... ids) {
return mediaStoreHelper.getAlbumArtPath(ids[0]);
}
protected void onPostExecute(String result) {
Picasso.with(context)
.load(new File(result))
.placeholder(R.drawable.ic_music)
.fit()
.into(imageView);
}
}
@Override
public void onBindViewHolder(SongViewHolder holder, int position) {
// Passing the binding operation to cursor loader
mCursorAdapter.getCursor().moveToPosition(position);
mCursorAdapter.bindView(holder.itemView, mContext, mCursorAdapter.getCursor());
}
@Override
public SongViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
// Passing the inflater job to the cursor-adapter
View v = mCursorAdapter.newView(mContext, mCursorAdapter.getCursor(), parent);
return new SongViewHolder(v);
}
}
有問題的部分是圖像加載與由兩個部分組成:
- 隨着ALBUMID我從
Cursor
了,我需要用ContentResolver
拿到專輯封面的文件路徑 - 使用文件路徑將圖像加載到
ImageView
中
T這兩段話需要在後臺完成,否則滾動將變得非常遲緩。在bindView
功能我叫AsyncTask
的做工作,但問題是,在滾動快,多種圖像請求闡述,這是結果:
正如你可以從代碼中看到我試圖取消對特定的ImageView
待定畢加索的請求,但這還不夠。這個問題能解決嗎?
我想你可以把onScroll聽者在RecyclerView,只有當它停止滾動啓動圖像加載。 – X3Btel
@ X3Btel不錯的想法,我會嘗試 – fillobotto