handler例子

package mars.barhandler;import android.app.Activity;import android.os.Bundle;import android.os.Handler;import android.os.Message;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;import android.widget.ProgressBar;public class TestBarHandler extends Activity {    /** Called when the activity is first created. *///声明控件变量ProgressBar bar = null;Button startButton = null;    @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.main);        //根据控件的ID得到代表控件的对象,并为按钮设置监听器        bar = (ProgressBar)findViewById(R.id.bar);        startButton = (Button)findViewById(R.id.startButton);        startButton.setOnClickListener(new ButtonListener());    }    //当点击startButton按钮时，就会执行ButtonListener的onClick方法    class ButtonListener implements OnClickListener{@Overridepublic void onClick(View v) {// TODO Auto-generated method stubbar.setVisibility(View.VISIBLE);updateBarHandler.post(updateThread);}        }    //使用匿名内部类来复写Handler当中的handleMessage方法    Handler updateBarHandler = new Handler(){@Overridepublic void handleMessage(Message msg) {bar.setProgress(msg.arg1);Bundle bundle = msg.getData();updateBarHandler.post(updateThread);System.out.println("test---->" + bundle.getString("test"));}        };    //线程类，该类使用匿名内部类的方式进行声明    Runnable updateThread = new Runnable(){    int i = 0 ;@Overridepublic void run() {System.out.println("Begin Thread" + i);i = i + 10 ;//得到一个消息对象，Message类是有Android操作系统提供Message msg = updateBarHandler.obtainMessage();//将msg对象的arg1参数的值设置为i,用arg1和arg2这两个成员变量传递消息，优点是系统性能消耗较少msg.arg1 = i ;Bundle bundle = new Bundle();bundle.putString("test", "test bundle");msg.setData(bundle);try {//设置当前显示睡眠1秒Thread.sleep(1000);} catch (InterruptedException e) {// TODO Auto-generated catch blocke.printStackTrace();}//将msg对象加入到消息队列当中if( i > 100){//如果当i的值为100时，就将线程对象从handler当中移除updateBarHandler.removeCallbacks(updateThread);System.out.println(">>>>>>");}else{updateBarHandler.sendMessage(msg);System.out.println("<<<<<<");}}    };    class MyThread extends Thread{    public void run(){        }    }    }