Android Message机制

参考链接http://www.cnblogs.com/hnrainll/archive/2012/01/06/2314863.html

package com.test.messagedemo;

import android.R.string;
import android.os.Bundle;
import android.os.Handler;
import android.os.Looper;
import android.os.Message;
import android.app.Activity;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;
import android.support.v4.app.NavUtils;

public class MainActivity extends Activity {
	private Button btn1,btn2,btn3,btn4;
	private TextView tv1,tv2,tv3,tv4;
	private static final String TAG = "Thread Id:";

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        btn1=(Button)findViewById(R.id.btn1);
        btn1.setOnClickListener(listener);
        tv1=(TextView)findViewById(R.id.tv1);
        btn2=(Button)findViewById(R.id.btn2);
        btn2.setOnClickListener(listener);
        tv2=(TextView)findViewById(R.id.tv2);
        btn3=(Button)findViewById(R.id.btn3);
        btn3.setOnClickListener(listener);
        tv3=(TextView)findViewById(R.id.tv3);
        btn4=(Button)findViewById(R.id.btn4);
        btn4.setOnClickListener(listener);
        tv4=(TextView)findViewById(R.id.tv4);
        
    }
    
    View.OnClickListener listener=new View.OnClickListener()
	{
		
		@Override
		public void onClick(View v)
		{
			// TODO Auto-generated method stub
			switch (v.getId())
			{
			case R.id.btn1://主线程给自己发送消息
				Looper looper;
				looper=Looper.myLooper();//获取当前线程的Looper，现在为主线程				
				EventHandler mHander=new EventHandler(looper);
				mHander.removeMessages(0);//删除队列消息
				String obj="This is main thread's message and received by itself!";
				Message m=mHander.obtainMessage(1, 1, 1, obj);				
				mHander.sendMessage(m);
				//mHander.handleMessage(m);//sendMessage后，Handler会自动调用handleMessage				
				break;
				
			case R.id.btn2://子线程给主线程发送消息
				NoLooperThread noLooperThread=new NoLooperThread();				
				noLooperThread.start();		
				break;
				
			case R.id.btn3://子线程给自己发送消息
				OwnLooperThread ownLooperThread=new OwnLooperThread();
				ownLooperThread.start();
				break;
				
			case R.id.btn4://主线程给子线程发送消息
				ReceiveMessageThread receiveMessageThread=new ReceiveMessageThread();
				receiveMessageThread.start();
				break;

			default:
				break;
			}
			
		}
	};
	
	private class EventHandler extends Handler
	{
    	
		public EventHandler(Looper looper)//这个方法必须写下来，否则这个类用不了
    	{
            super (looper);
            
    	}
		@Override
		public void handleMessage(Message msg)
		{
			// TODO Auto-generated method stub
			switch (msg.what)
			{
			case 1:
				tv1.setText(msg.obj.toString());
						
				break;				
			case 2:
				tv2.setText(msg.obj.toString());			
							
			case 3:
				tv3.setText(msg.obj.toString());
				break;
				
			case 4:
				tv4.setText(msg.obj.toString());
				break;
				
			default:
				break;
			}			
			
		}		
	}
	
	private class NoLooperThread extends Thread
	{
		private EventHandler mNoLooperThreadHandler; 
		@Override
		public void run()
		{
			Looper looper=Looper.getMainLooper();
			mNoLooperThreadHandler=new EventHandler(looper);
			mNoLooperThreadHandler.removeMessages(0);
			String obj="This is the message from otherThread to MainThread!";
			Message m=mNoLooperThreadHandler.obtainMessage(2, 1, 1, obj);
			mNoLooperThreadHandler.sendMessage(m);
			//mNoLooperThreadHandler.handleMessage(m);
			Log.i(TAG, "NoLooperThread id:" + this.getId()); //注意将long型转成String的一个技巧
		}
		
	}
	
    private class OwnLooperThread extends Thread
    {
    	private EventHandler mOwnLooperEventHandler;
		@Override
		public void run()
		{
			// TODO Auto-generated method stub
			Looper.prepare();
			Looper looper=Looper.myLooper();
			mOwnLooperEventHandler=new EventHandler(looper);
			mOwnLooperEventHandler.removeMessages(0);
			String obj="This is message from otherThread and to itself!";
			Message m=mOwnLooperEventHandler.obtainMessage(3, 1, 1, obj);
			mOwnLooperEventHandler.sendMessage(m);
			//mOwnLooperEventHandler.handleMessage(m);
			Log.i(TAG, "ownLooperThread id:" + this.getId()); 
		}
    	
    }

    private class ReceiveMessageThread extends Thread
    {

    	private EventHandler mReceiveMessageHandler;
		@Override
		public void run()
		{
			// TODO Auto-generated method stub
			Looper.prepare();
			Looper looper=Looper.getMainLooper();
			mReceiveMessageHandler=new EventHandler(looper);
			mReceiveMessageHandler.removeMessages(0);
			String obj="This is message from MainThread  to OtherThread!";
			Message m=mReceiveMessageHandler.obtainMessage(4, 1, 1, obj);
			mReceiveMessageHandler.sendMessage(m);	
			Log.i(TAG, "ReceiveLooperThread id:" + this.getId()); 		
			
		}
    	
    }
    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.activity_main, menu);
        return true;
    }

    
}