Android线程模型和AsyncTask(2)

ublic class CanvasImageTask extends AsyncTask<ImageView, Void, Bitmap>{            private ImageView gView ;                    protected Bitmap doInBackground(ImageView... views) {                    Bitmap bmp = null ;                    ImageView view = views[0];                // 根据iconUrl获取图片并渲染，iconUrl的url放在了view的tag中。                if (view.getTag() != null) {                        try {                           URL url = new URL(view.getTag().toString());                           HttpURLConnection conn = (HttpURLConnection)url.openConnection();                           conn.setDoInput(true);                           conn.connect();                           InputStream stream = conn.getInputStream();                           bmp = BitmapFactory.decodeStream(stream);                           stream.close();                        } catch (Exception e) {                                    Log.v("img", e.getMessage());                                return null;                        }                }                this.gView = view;                return bmp;        }        protected void onPostExecute(Bitmap bm) {                if (bm != null) {                        this.gView.setImageBitmap(bm);                        this.gView = null ;                }        }            }    在Activity中直接调用    if(!img.isDrawingCacheEnabled() || !holder.image.getTag().equals(imgpath)){                    img.setImageResource(R.drawable.icon_app);                    img.setTag(imgpath);                    try{                        new CanvasImageTask().execute(img);                        img.setDrawingCacheEnabled(true);                    }catch (Exception e) {                        Log.e("error", "RejectedExecutionException in content_img: " +  imgpath);  

这样图片加载使用异步线程便不会进行堵塞发生错误，我们还可以使用 callback 在图片加载完后进行回调