android handler用法和实例

package com.cn;

import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.os.Looper;
import android.os.Message;
import android.util.Log;
import android.widget.Button;

public class TestHandlerActivity extends Activity {
 public Button button;
 public MyHandler myHandler;

 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.main);

  button = (Button) findViewById(R.id.button);
 
 
  myHandler = new MyHandler(); //接收数据   与主Activity主线程一起启动
  
 
  
  // 当创建一个新的Handler实例时, 它会绑定到当前线程和消息的队列中,开始分发数据
  // Handler有两个作用, (1) : 定时执行Message和Runnalbe 对象
  // (2): 让一个动作,在不同的线程中执行.

  // 它安排消息,用以下方法
  // post(Runnable)
  // postAtTime(Runnable,long)
  // postDelayed(Runnable,long)
  // sendEmptyMessage(int)
  // sendMessage(Message);
  // sendMessageAtTime(Message,long)
  // sendMessageDelayed(Message,long)

  // 以上方法以 post开头的允许你处理Runnable对象
  // sendMessage()允许你处理Message对象(Message里可以包含数据,)
  MyThread m = new MyThread();
  new Thread(m).start();//启动子线程并向handler发送和更新消息
 
 }

 /**
  * 接受消息,处理消息 ,此Handler会与当前主线程一块运行
  * */

 class MyHandler extends Handler {
 
  public MyHandler() {
   TestHandlerActivity.this.button.setText("你好我是Handler---");
  }

  public MyHandler(Looper L) {
   super(L);
  }

  // 子类必须重写此方法,接受数据
  @Override
  public void handleMessage(Message msg) {
   // TODO Auto-generated method stub
   Log.d("MyHandler", "handleMessage......");
   super.handleMessage(msg);
   // 此处可以更新UI
   Bundle b = msg.getData();
   String color = b.getString("color");
   TestHandlerActivity.this.button.append(color);

  }
 }

 class MyThread implements Runnable {
  public void run() {

   try {
    Thread.sleep(2000);
   } catch (InterruptedException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
   }

   Log.d("thread.......", "mThread........");
   Message msg = new Message();
   Bundle b = new Bundle();// 存放数据
   b.putString("color", "我的");
   msg.setData(b);

   TestHandlerActivity.this.myHandler.sendMessage(msg); // 向Handler发送消息,更新UI

  }
 }
}