android之消息机制（一）

消息操作类Handler

首先编写main.xml文件代码如下：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent" >
	<TextView 
	    android:id="@+id/info"
	    android:layout_width="fill_parent"
	    android:layout_height="wrap_content"/>
</LinearLayout>
 

　　然后改写Activity.java类

代码如下：

package com.example.myfirstproject;

import java.util.ArrayList;
import java.util.List;
import java.util.Timer;
import java.util.TimerTask;

import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.app.Activity;
import android.content.pm.ActivityInfo;
import android.content.res.Configuration;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.*;

public class MainActivity extends Activity {
	private static int count = 0;
	public static final int SET = 1;
	private Handler myHandler = new Handler(){
		public void handleMessage(android.os.Message msg){
			switch(msg.what){
			case SET:
				MainActivity.this.info.setText("MLDN-"+count++);
			}
		}
	};
	private TextView info = null;
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        this.info = (TextView)super.findViewById(R.id.info);
        Timer timer = new Timer();
        timer.schedule(new MyTask(), 0, 1000);
    }    
    private class MyTask extends TimerTask{
    	public void run(){
    		Message msg = new Message();
    		msg.what = SET;
    		MainActivity.this.myHandler.sendMessage(msg);
    	}
    }
}

　　运行效果：