Android 的消息机制（3）

/**
* MessageQueue2.java
* com.test
*
* Function： TODO
*
*   ver     date           author
* ──────────────────────────────────
*           2011-3-20      Leon
*
* Copyright (c) 2011, TNT All Rights Reserved.
*/

package com.test.messagequeue;
/**
* ClassName:MessageQueue2
* Function: TODO ADD FUNCTION
* Reason:   TODO ADD REASON
*
* @author   Leon
* @version
* @since    Ver 1.1
* @Date     2011-3-20
*/
import android.app.Activity;
import android.graphics.Color;
import android.os.Bundle;
import android.os.Handler;
import android.os.Looper;
import android.os.Message;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.LinearLayout;
import android.widget.TextView;

public class MessageQueue3 extends Activity implements OnClickListener {
private final int WC = LinearLayout.LayoutParams.WRAP_CONTENT;
private final int FP = LinearLayout.LayoutParams.FILL_PARENT;
public TextView tv;
private myThread t;
private Button btn, btn2, btn3;
private EHandler mHandler;

public void onCreate(Bundle icicle) {
super.onCreate(icicle);
LinearLayout layout = new LinearLayout(this);
layout.setOrientation(LinearLayout.VERTICAL);

btn = new Button(this);
btn.setId(101);
btn.setText("test looper");
btn.setOnClickListener(this);
LinearLayout.LayoutParams param =
new LinearLayout.LayoutParams(100,50);
param.topMargin = 10;
layout.addView(btn, param);

btn2 = new Button(this);
btn2.setId(102);
btn2.setText("exit");
btn2.setOnClickListener(this);
layout.addView(btn2, param);

tv = new TextView(this);
tv.setTextColor(Color.WHITE);
tv.setText("");
LinearLayout.LayoutParams param2 =
new LinearLayout.LayoutParams(FP, WC);
param2.topMargin = 10;
layout.addView(tv, param2);
setContentView(layout);
}
public void onClick(View v) {
switch(v.getId()){
case 101:
//           mHandler = new EHandler(Looper.myLooper());
//可以隐式的制定Looper,和上面的效果是一样的
mHandler = new EHandler();
t = new myThread();
t.start();
break;
case 102:
finish();
break;
}
}
//------------------------------------------------------
class EHandler extends Handler {
public EHandler(Looper looper) {
super(looper);
}
public EHandler(){

}
@Override
public void handleMessage(Message msg) {
tv.setText((String)msg.obj);
}
}
//------------------------------------------------------
class myThread extends Thread{

public void run() {

String obj = "This message is from new thread.";
mHandler.removeMessages(0);
Message m = mHandler.obtainMessage(1, 1, 1, obj);
mHandler.sendMessage(m);
}
}