让用户不再遭遇ANR

• ANR简介
      Android有专门的Thread来负责处理如下的case:
         1)在规定时间内没有响应用户输入(例如: 按键, 触摸屏幕)
         2)在规定时间内没有执行完毕BroadcastReceiver
       此时，系统会向用户显示一个对话框，这个对话框称作应用程序无响应(ANR:Application NotResponding)对话框。

• 避免ANR
     引起ANR的本质原因是: 主(main) Thread 过于繁忙，不能处理用户输入。避免ANR就需要把那些阻塞main thread的东西，移植到子线程去作(下面分别是引起ANR的代码和 优化后的代码)。

//cause ANR
 public void onUpdate(int itemPos,  final String itemName, UpdateInfo update) {
	             final String[] fields = new String[5];
	             fields[0] = notifyValue(update, X1);
	             fields[1] = notifyValue(update, X2);
	             fields[2] = notifyValue(update, X3);
	             fields[3] = notifyValue(update, X4);
	             fields[4] = notifyValue(update, X5);
	             
                Message msg =  messageHandler.obtainMessage(); 
                msg.what = MESSAGE_HANDLE_ID_UPDATEROW_DATA;
				Bundle bundle = new Bundle();
				bundle.putInt(MESSAGE_KEY_ID, Integer.parseInt(itemName, 10));
				bundle.putString(X1,  fields[0] );
				bundle.putString(X2, fields[1]);
				bundle.putString(X3, fields[2]);
				bundle.putString(X4, fields[3]);
				bundle.putString(X5, fields[4]);
				msg.setData(bundle);
				messageHandler.sendMessage(msg);
}


private  Handler messageHandler = new Handler() {

		@Override
		public void handleMessage(Message msg) {
			
		switch(msg.what) {
			case  MESSAGE_HANDLE_ID_UPDATEROW_DATA:{
			  int id = msg.getData().getInt(MESSAGE_KEY_ID);
				String fields[] = new String[5];
				fields[0] = msg.getData().getString(X1);
				fields[1] = msg.getData().getString(X2);
				fields[2] = msg.getData().getString(X3);
				fields[3] = msg.getData().getString(X4);
				fields[4] = msg.getData().getString(X5);
				updateRowInTable(id, fields);
				break;
			}
}

// high performance
 public void onUpdate(int itemPos,  final String itemName, UpdateInfo update) {
	             final String[] fields = new String[5];
	             fields[0] = notifyValue(update, X1);
	             fields[1] = notifyValue(update, X2);
	             fields[2] = notifyValue(update, X3);
	             fields[3] = notifyValue(update, X4);
	             fields[4] = notifyValue(update, X5);

			final Runnable myUpdateResults = new Runnable() {
			        public void run() {
			        	updateRowInTable(Integer.parseInt(itemName, 10), fields);
			        }
			    };
			    
			     new Thread() {
		            public void run() {
		            	messageHandler.post(myUpdateResults);
		            }
		        }.start();

 private  Handler messageHandler = new Handler();