Handler制作简单相册查看器的实例代码

<&＃63;xml version="1.0" encoding="utf-8"&＃63;>

  

package com.example.sample_9_9;
public class MyTread extends Thread{    //继承自线程类
  HandlerSampleActivity activity;     //activity引用
  int what = 1;              //发送消息的what值
  public MyTread(HandlerSampleActivity activity){ //构造器
    this.activity = activity;    //得到activity的引用
  }
  @Override
  public void run(){
    while(true){       //循环
      activity.myHandler.sendEmptyMessage((what++)%4);
      //发送消息，%4是因为只有四张图进行轮换
      try{
        Thread.sleep(2000);    //睡眠两秒钟
      }
      catch (Exception e){     //捕获异常
        e.printStackTrace();   //打印异常
      }
    }
  }
}

package com.example.sample_9_9;
import android.os.Handler;
import android.os.Message;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.ImageView;
public class HandlerSampleActivity extends AppCompatActivity {
  ImageView myImageView;
  Handler myHandler = new Handler() { //创建一个Handler对象
    @Override
    public void handleMessage(Message msg) {  //重写接收消息的方法
      switch (msg.what) { //判断what值
        case 0:
          myImageView.setImageResource(R.drawable .a);
          break;
        case 1:
          myImageView.setImageResource(R.drawable .b);
          break;
        case 2:
          myImageView.setImageResource(R.drawable .c);
          break;
        case 3:
          myImageView.setImageResource(R.drawable .d);
          break;
      }
      super.handleMessage(msg);
    }
  };
  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_handler_sample);
    myImageView = (ImageView) findViewById(R.id.myImageView);
    MyTread myThread = new MyTread(this);  //初始化线程
    myThread.start(); //启动线程
  }
}