今天学习到Service,在用Service下载文件时,一个问题就是Service没有界面,如何通知用户当前下载的进度,Service直接向Activity传数据有点麻烦,于是想到了用Broadcast,Service广播,Activity负责接收,再对接收到的数据进行处理,就达到了我们的目的。下面是今天这个程序的运行效果:

先注册Receiver,然后开始Service,上面的TextView和ProgressBar就会随着Service传过来的值变,解除注册Receiver或者结束Service后不会再变。
Service代码:
 
package com.services;

import android.app.Service;
import android.content.Intent;
import android.os.IBinder;
import android.util.Log;

public class TestService extends Service {
boolean isStop=false;
@Override
public IBinder onBind(Intent intent) {
// TODO Auto-generated method stub
Log.i("TAG","绑定");
return null;
}
public void onCreate(){
Log.i("TAG","Services onCreate");
super.onCreate();
}
public void onStart(Intent intent,int startId){
Log.i("TAG","Services onStart");
super.onStart(intent, startId);
new Thread(){//新建线程,每隔1秒发送一次广播,同时把i放进intent传出
public void run(){
int i=0;
while(!isStop){
Intent intent=new Intent();
intent.putExtra("i", i);
i++;
intent.setAction("android.intent.action.test");//action与接收器相同
sendBroadcast(intent);
Log.i("TAG",String.valueOf(i));
try {
sleep(1000);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}.start();

}
@Override
public void onDestroy() {
Log.i("TAG","Services onDestory");
isStop=true;//即使service销毁线程也不会停止,所以这里通过设置isStop来停止线程
super.onDestroy();
}

}
 
Activity代码:
 
package com.services;
    
    
import android.app.Activity;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.ProgressBar;
import android.widget.TextView;
    
public class main extends Activity {
  /** Called when the activity is first created. */
  Button b1,b2,b3,b4;
  TestService mService;
  ProgressBar pb;
  MyReceiver receiver;
  TextView tv;
  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    b1=(Button)findViewById(R.id.b1);
    b2=(Button)findViewById(R.id.b2);
    b3=(Button)findViewById(R.id.b3);
    b4=(Button)findViewById(R.id.b4);
    b1.setOnClickListener(l1);
    b2.setOnClickListener(l2);
    b3.setOnClickListener(l3);
    b4.setOnClickListener(l4);
    pb=(ProgressBar)findViewById(R.id.pb);
    tv=(TextView)findViewById(R.id.tv);
  }
    
    
    
  public class MyReceiver extends BroadcastReceiver {
    //自定义一个广播接收器
    @Override
    public void onReceive(Context context, Intent intent) {
      // TODO Auto-generated method stub
      System.out.println("OnReceiver");
      Bundle bundle=intent.getExtras();
      int a=bundle.getInt("i");
      pb.setProgress(a);
      tv.setText(String.valueOf(a));
      //处理接收到的内容
    
    }
    public MyReceiver(){
      System.out.println("MyReceiver");
      //构造函数,做一些初始化工作,本例中无任何作用
    }
    
  }
    
    
  OnClickListener l1=new OnClickListener(){
    
    @Override
    public void onClick(View v) {
      // TODO Auto-generated method stub
      startService(new Intent(main.this, TestService.class));
      //开始服务
    }
    
  };
  OnClickListener l2=new OnClickListener(){
    
    @Override
    public void onClick(View v) {
      // TODO Auto-generated method stub
      stopService(new Intent(main.this, TestService.class));
      //结束服务
    }
    
  };
  OnClickListener l3=new OnClickListener(){
    
    @Override
    public void onClick(View v) {
      // TODO Auto-generated method stub
      //注册接收器
      receiver=new MyReceiver();
      IntentFilter filter=new IntentFilter();
      filter.addAction("android.intent.action.test");
      main.this.registerReceiver(receiver,filter);
    }
    
  };
  OnClickListener l4=new OnClickListener(){
    
    @Override
    public void onClick(View v) {
      // TODO Auto-generated method stub        
      main.this.unregisterReceiver(receiver);
      //解除注册接收器
    }
    
  };
}