package ispring.com.testhandler;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;


public class MainActivity extends Activity implements Button.OnClickListener {

 private TextView statusTextView = null;

 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);
  statusTextView = (TextView)findViewById(R.id.statusTextView);
  Button btnDownload = (Button)findViewById(R.id.btnDownload);
  btnDownload.setOnClickListener(this);
 }

 @Override
 public void onClick(View v) {
  DownloadThread downloadThread = new DownloadThread();
  downloadThread.start();
 }

 class DownloadThread extends Thread{
  @Override
  public void run() {
   try{
    System.out.println("开始下载文件");
    //此处让线程DownloadThread休眠5秒中，模拟文件的耗时过程
    Thread.sleep(5000);
    System.out.println("文件下载完成");
    //文件下载完成后更新UI
    MainActivity.this.statusTextView.setText("文件下载完成");
   }catch (InterruptedException e){
    e.printStackTrace();
   }
  }
 }
}

package ispring.com.testhandler;

import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;


public class MainActivity extends Activity implements Button.OnClickListener {

 private TextView statusTextView = null;

 //uiHandler在主线程中创建，所以自动绑定主线程
 private Handler uiHandler = new Handler();

 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);
  statusTextView = (TextView)findViewById(R.id.statusTextView);
  Button btnDownload = (Button)findViewById(R.id.btnDownload);
  btnDownload.setOnClickListener(this);
  System.out.println("Main thread id " + Thread.currentThread().getId());
 }

 @Override
 public void onClick(View v) {
  DownloadThread downloadThread = new DownloadThread();
  downloadThread.start();
 }

 class DownloadThread extends Thread{
  @Override
  public void run() {
   try{
    System.out.println("DownloadThread id " + Thread.currentThread().getId());
    System.out.println("开始下载文件");
    //此处让线程DownloadThread休眠5秒中，模拟文件的耗时过程
    Thread.sleep(5000);
    System.out.println("文件下载完成");
    //文件下载完成后更新UI
    Runnable runnable = new Runnable() {
     @Override
     public void run() {
      System.out.println("Runnable thread id " + Thread.currentThread().getId());
      MainActivity.this.statusTextView.setText("文件下载完成");
     }
    };
    uiHandler.post(runnable);
   }catch (InterruptedException e){
    e.printStackTrace();
   }
  }
 }
}

package ispring.com.testhandler;

import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;


public class MainActivity extends Activity implements Button.OnClickListener {

 private TextView statusTextView = null;

 //uiHandler在主线程中创建，所以自动绑定主线程
 private Handler uiHandler = new Handler(){
  @Override
  public void handleMessage(Message msg) {
   switch (msg.what){
    case 1:
     System.out.println("handleMessage thread id " + Thread.currentThread().getId());
     System.out.println("msg.arg1:" + msg.arg1);
     System.out.println("msg.arg2:" + msg.arg2);
     MainActivity.this.statusTextView.setText("文件下载完成");
     break;
   }
  }
 };

 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);
  statusTextView = (TextView)findViewById(R.id.statusTextView);
  Button btnDownload = (Button)findViewById(R.id.btnDownload);
  btnDownload.setOnClickListener(this);
  System.out.println("Main thread id " + Thread.currentThread().getId());
 }

 @Override
 public void onClick(View v) {
  DownloadThread downloadThread = new DownloadThread();
  downloadThread.start();
 }

 class DownloadThread extends Thread{
  @Override
  public void run() {
   try{
    System.out.println("DownloadThread id " + Thread.currentThread().getId());
    System.out.println("开始下载文件");
    //此处让线程DownloadThread休眠5秒中，模拟文件的耗时过程
    Thread.sleep(5000);
    System.out.println("文件下载完成");
    //文件下载完成后更新UI
    Message msg = new Message();
    //虽然Message的构造函数式public的，我们也可以通过以下两种方式通过循环对象获取Message
    //msg = Message.obtain(uiHandler);
    //msg = uiHandler.obtainMessage();

    //what是我们自定义的一个Message的识别码，以便于在Handler的handleMessage方法中根据what识别
    //出不同的Message，以便我们做出不同的处理操作
    msg.what = 1;

    //我们可以通过arg1和arg2给Message传入简单的数据
    msg.arg1 = 123;
    msg.arg2 = 321;
    //我们也可以通过给obj赋值Object类型传递向Message传入任意数据
    //msg.obj = null;
    //我们还可以通过setData方法和getData方法向Message中写入和读取Bundle类型的数据
    //msg.setData(null);
    //Bundle data = msg.getData();

    //将该Message发送给对应的Handler
    uiHandler.sendMessage(msg);
   }catch (InterruptedException e){
    e.printStackTrace();
   }
  }
 }
}