Handler的学习（二）

package com.example.handledemos;

import android.app.Activity;

import android.os.Bundle;

import android.os.Handler;

import android.os.Handler.Callback;

import android.os.Message;

import android.util.Log;

import android.view.View;

import android.view.View.OnClickListener;

import android.widget.Button;

import android.widget.ImageView;

import android.widget.TextView;

import android.widget.Toast;

/**

* Handler的用法

* 1、Handler用于发送和处理消息。

* 2、在多线程中更新ui。

* @author lzl

*传入的callback类用于拦截handler发送的消息。

*/

public class MainActivity extends Activity implements OnClickListener {

private TextView textView;

private ImageView imageView;

private Button button;

int images[] = {R.drawable.iamge1,R.drawable.image2,R.drawable.image3};

private int index;

private MyRunnerble myrunnerble = new MyRunnerble();   //这里是创建对象

private Handler handler = new Handler(new Callback() {    //callback类 用于拦截发送的信息。

@Override

public boolean handleMessage(Message msg) {

if(msg.arg1 == 10){

Toast.makeText(getApplicationContext(), "---"+msg.arg1, Toast.LENGTH_SHORT).show();

handler.removeCallbacks(myrunnerble);

return true;

}

return false;

}

}){

public void handleMessage(Message msg) {

Toast.makeText(getApplicationContext(), "***"+msg.arg1, Toast.LENGTH_SHORT).show();

}

};

class MyRunnerble implements Runnable{

@Override

public void run() {

index++;

index = index % 3;

handler.postDelayed(myrunnerble, 1000);   //在线程中执行，延迟时间1秒。

imageView.setImageResource(images[index]);

}

}

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

imageView = (ImageView) findViewById(R.id.imageView1);

button = (Button) findViewById(R.id.button1);

button.setOnClickListener(this);

handler.postDelayed(myrunnerble, 1000);

}

@Override

public void onClick(View view) {

//        handler.removeCallbacks(myrunnerble);   //通过点击事件使图片停止切换。

Message message = new Message();

message.arg1 = 10;

handler.sendMessage(message);

}

}