Handler消息传递机制Demo

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说明：

要想在非主线程中，创建Handler对象，首先需要使用Looper类的prepare方法来初始化一个Looper对象，然后创建这个Handler对象，再使用Looper类的loop方法，启动looper，从消息队列里获取和处理消息　。

public void run(){

super.run();

Looper.prepare();

//实例化一个Handler对象

//....................

Looper.loop();

}

下面用一个Demo(图片随机展示)

AndroidManifest.xml:

activity_main.xml

MainActivity.java:

package com.example.demohandler;

import java.util.Random;

import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.view.Menu;
import android.widget.ImageView;
import android.widget.TextView;

public class MainActivity extends Activity implements Runnable{
	
	private ImageView iv ;
	private Handler handler;
	private int[] path= new int[]{R.drawable.img1,R.drawable.img3,R.drawable.img3,R.drawable.img4};
	
	private String[] title = new String[]{"高清壁纸1","高清壁纸2","高清壁纸3","高清壁纸4"};

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		
		iv = (ImageView)findViewById(R.id.imageView1);
		
		Thread t = new Thread(this);
		t.start();
		
		handler = new Handler(){
			public void handleMessage(Message msg){
				TextView tv = (TextView)findViewById(R.id.textView1);
				if(msg.what ==0x101){
					tv.setText(msg.getData().getString("title"));
					iv.setImageResource(path[msg.arg1]);
				}
				super.handleMessage(msg);
			}
		};
	}

	@Override
	public boolean onCreateOptionsMenu(Menu menu) {
		// Inflate the menu; this adds items to the action bar if it is present.
		getMenuInflater().inflate(R.menu.main, menu);
		return true;
	}

	@Override
	public void run() {
		// TODO Auto-generated method stub
		int index =0;
		while(!Thread.currentThread().isInterrupted()){
			index = new Random().nextInt(path.length);//产生一个随机数
			Message m = handler.obtainMessage();//获取一个Message
			m.arg1 = index;//保存要显示广告图片的索引值
			Bundle bundle = new Bundle();//
			m.what = 0x101;//设置消息标识
			bundle.putString("title", title[index]);//保存标题
			m.setData(bundle);//将Bundle对象保存到Message中
			
			handler.sendMessage(m);//发送消息
			try{
				Thread.sleep(2000);
			}catch(InterruptedException e){
				e.printStackTrace();
			}
		}
	}

}

转载于:https://my.oschina.net/u/2552902/blog/543986