问网络图像检索

EN

private class DealsAdapter extends ArrayAdapter<Item> {      

  public DealsAdapter(List<Item> items) {
     super(DealList.this, R.layout.list_item, items);
  }

  @Override
  public View getView(int position, View convertView, ViewGroup parent) {

     if (convertView == null) {
        LayoutInflater inflater = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        convertView = inflater.inflate(R.layout.list_item, parent, false);
     }

     // use ViewHolder here to prevent multiple calls to findViewById (if you have a large collection)
     TextView text = (TextView) convertView.findViewById(R.id.deal_title);
     ImageView image = (ImageView) convertView.findViewById(R.id.deal_img);
     image.setImageBitmap(BitmapFactory.decodeResource(getResources(), R.drawable.ddicon));

     Item item = getItem(position);

     if (item != null) {
        text.setText(item.getTitle());
        Bitmap bitmap = app.getImageCache().get(item.getItemId()); //<------HERE
        if (bitmap != null) {
           image.setImageBitmap(bitmap);
        } else {
           // put item ID on image as TAG for use in task
           image.setTag(item.getItemId());
           // separate thread/via task, for retrieving each image
           // (note that this is brittle as is, should stop all threads in onPause)               
           new RetrieveImageTask(image).execute(item.getSmallPicUrl());
        }
     }
     return convertView;
  }
}

private class RetrieveImageTask extends AsyncTask<String, Void, Bitmap> {
  private ImageView imageView;

  public RetrieveImageTask(ImageView imageView) {
     this.imageView = imageView;
  }

  @Override
  protected Bitmap doInBackground(String... args) {
     Bitmap bitmap = app.retrieveBitmap(args[0]);
     return bitmap;
  }

  @Override
  protected void onPostExecute(Bitmap bitmap) {
     if (bitmap != null) {
        imageView.setImageBitmap(bitmap);
        app.getImageCache().put((Long) imageView.getTag(), bitmap);
        imageView.setTag(null);
     }
  }