android开发之Handler的使用

package com.lintao.handledemo;

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.TextView;

/**
 * 通过线程修改UI
 * @author admin
 *
 */
public class MainActivity extends Activity {

    private TextView mTvHandlerDemo;

    private Handler myHandler;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mTvHandlerDemo = (TextView)findViewById(R.id.tv_handler_demo);
        
        //实例化一个Handler
        myHandler = new MyHandler();
        //实例化一个Runnable接口
        MyThread m = new MyThread();
        //启动该接口
        new Thread(m).start();
    }

    /**
     * 接受消息并处理消息 ,此Handler会与当前主线程一块运行，可以用来改变UI等
     */
    class MyHandler extends Handler {
        // 子类必须重写此方法,接受数据
        @Override
        public void handleMessage(Message msg) {
            // TODO Auto-generated method stub
            super.handleMessage(msg);
            // 此处可以更新UI
            Bundle b = msg.getData();
            String color = b.getString("text");
            MainActivity.this.mTvHandlerDemo.setText(color);
        }
    }

    /**
     * 这里就可以用来处理主线程以后的工作，等完成后可以发送信息给主线程
     * @author admin
     *
     */
    class MyThread implements Runnable {
        public void run() {
            //隔了10s
            try {
                Thread.sleep(10000);
            } catch (InterruptedException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            //构造Message
            Message msg = new Message();
            Bundle b = new Bundle();// 存放数据
              b.putString("text", "改变UI");
            msg.setData(b);

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

        }
    }

}

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.lintao.handledemo.MainActivity$PlaceholderFragment" >

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/hello_world"
        android:id="@+id/tv_handler_demo" />

</RelativeLayout>