如何更新ImageView中的位图

Question

protected Bitmap doInBackground(String...params) {
        // TODO Auto-generated method stub
         try {
              /* Open a new URL and get the InputStream to load data from it. */
              URL aURL = new URL(params[0]);
              URLConnection conn = aURL.openConnection();
              conn.connect();
              InputStream is = conn.getInputStream();
              /* Buffered is always good for a performance plus. */
              BufferedInputStream bis = new BufferedInputStream(is);
              /* Decode url-data to a bitmap. */
              Bitmap bm = BitmapFactory.decodeStream(bis);
              b1=bm;
              bis.close();
              is.close();
          } catch (IOException e) 
          {
              Log.e("DEBUGTAG", "Remote Image Exception", e);
          }
       return null;
   }
// TODO Auto-generated method stub
        super.onPostExecute(result);
        i1.setImageBitmap(b1);
        Animation rotation = AnimationUtils.loadAnimation(MainActivity.this, R.anim.rotate);
     i1.startAnimation(rotation);
    //System.out.println("imageview is working");
        try {
            System.out.println("thread going to sleep");
            Thread.sleep(2000);
        } catch (InterruptedException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        i1.setImageBitmap(b1);
        }

我正在通过位图显示来自Internet的图像，现在我使用了另一个图像，通过更新URL，但我无法显示此图像仅显示上一个图像，如果我运行这仅在循环中，最后一个图像是在示意吗？有任何建议

Answer 1

从您的on treate或您想从网络下载代码

的地方

new Thread(new Runnable() {
                public void run() {
                    Drawable drawable = createDrawableFromURL(_mDrawingURL);
                    Message msgURL = new Message();
                    msgURL.arg2 = URL_CONSTANT;
                    msgURL.obj = drawable;
                    _handler_url.sendMessage(msgURL);   
                }
            }).start();
        } catch (JSONException e) {
            e.printStackTrace();
        } 
    }

此方法将用于从Internet下载图像：

private Drawable createDrawableFromURL(String urlString) {
        Drawable image = null;
        try
        {
            InputStream inputStream = new URL(urlString).openStream();
            image = Drawable.createFromStream(inputStream, null);
            inputStream.close();
        }
        catch (MalformedURLException e) {
            e.printStackTrace();
            image = null;
        } catch (IOException e) {
            e.printStackTrace();
            image = null;
        }
        return image;
    }

下载图像后，图像视图将使用图像进行更新。：

private Handler _handler_url = new Handler(){
        public void dispatchMessage(Message msg) {
            switch (msg.arg2) {
            case URL_CONSTANT:
                Drawable drawable = (Drawable) msg.obj;
                if(drawable!=null)
                    _mImageView.setImageDrawable(drawable);
                break;
            default:
                break;
            }
        };
    };