Android Handler简单例子

package com.example.handler;

import android.os.Bundle;
import android.app.Activity;
import android.app.ProgressDialog;
import android.content.res.Resources;
import android.os.Handler;
import android.os.Message;
import android.util.Log;
import android.view.View;
import android.widget.Button;

public class MainActivity extends Activity {

//声明变量
private Button b1;
private ProgressDialog pd;

//定义Handler对象
private Handler handler =new Handler(){
@Override
//当有消息发送出来的时候就执行Handler的这个方法
public void handleMessage(Message msg){
super.handleMessage(msg);
//只要执行到这里就关闭对话框
pd.dismiss();
}
};

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

Resources res=  this.getResources();
//查看UI组件所在的线程名
Log.i("tag", "onCreate()-->"+Thread.currentThread().getName());

//定义UI组件
b1= (Button)findViewById(R.id.Button01);
//给按钮绑定单击事件监听器
b1.setOnClickListener(new View.OnClickListener() {

@Override
public void onClick(View v) {
//点击按钮后去处理长耗时操作
processThread();
}
});
}

private void processThread(){

//构建一个下载进度条
pd= ProgressDialog.show(MainActivity.this, "下载文件", "正在下载……");
Log.i("tag", "processThread()-->"+Thread.currentThread().getName());

new Thread(){

@Override
public void run(){
Log.i("tag", "run()-->"+Thread.currentThread().getName());
//在新线程里执行长耗时方法
longTimeMethod();
//执行完毕后给handler发送一个空消息
handler.sendEmptyMessage(0);
}

}.start();
}

//模拟下载文件的长耗时方法
private void longTimeMethod(){
try {
Log.i("tag", "longTimeMethod-->"+Thread.currentThread().getName());
Thread.sleep(10000);
} catch (InterruptedException e) {
e.printStackTrace();
}
}

}