線程中更新UI

在android中更新UI爲非線程安全的。所以想在線程中更新UI必須和Handler配合。

例：

private ImageView imgHead;
private Handler handler=new Handler(){

		@Override
		public void handleMessage(Message msg) {
			switch (msg.what) {
			case 1:
				imgHead.setImageBitmap((Bitmap)msg.obj);
				break;
			default:
				break;
			}
		}
	};
	Runnable downloadRun = new Runnable(){
		@Override        
		public void run() {            
			URL url;
            Bitmap bitmap = null;
            try {
                    url = new URL("http://tp1.sinaimg.cn/2118986604/180/5633348097/1");
                    InputStream is = url.openConnection().getInputStream();
                    BufferedInputStream bis = new BufferedInputStream(is);
                    bitmap = BitmapFactory.decodeStream(bis);
                    bis.close();
            } catch (MalformedURLException e) {
                    e.printStackTrace();
            } catch (IOException e) {
                    e.printStackTrace();
            }
            handler.obtainMessage(1,bitmap).sendToTarget();
          //Bitmap bitmap = getBitmapFromUrl("http://tp1.sinaimg.cn/2118986604/50/5633348097/1");
			//imgHead.setImageBitmap(bitmap);
			//imgHead.invalidate();
		}
	};
protected void onCreate(Bundle savedInstanceState) {
	imgHead=(ImageView) this.findViewById(R.id.img_head);
new Thread(downloadRun).start();
	}