Android笔记二十五.Android事件Handler消息传递机制

package com.example.android_handler;
import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.widget.TextView;
public class HandlerTest extends Activity {
 int i=0;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        final TextView text = (TextView)findViewById(R.id.random);
        //1.创建一个Handler类对象，并重写handleMessage()方法
        final Handler handler = new Handler(){
   @Override
   public void handleMessage(Message msg)
   {
    if(msg.what==0x520)
    {
     text.setText("获得的新随机数为：\n"+Math.random());
    }
   }
        };
     
        //2.定义一个计时器。让该计时器以1.2s周期性地运行指定任务(毫秒为基本单位)
//       new Timer().schedule(new TimerTask(){
//	 public void run() {
//	 handler.sendEmptyMessage(0x520);
//	 }
//        }, 0, 1200);
        new Thread(new Runnable(){
   public void run() {
    while(true)
    {
     try {
      Thread.sleep(1200);
     } catch (Exception e) {
      e.printStackTrace();
     }
     handler.sendEmptyMessage(0x520);
    }
   }
        }).start();
    }
}

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >
    <TextView
        android:id="@+id/random"
        android:textSize="20sp"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="35dp"
        android:layout_gravity="center"/>
</LinearLayout>