Service通过广播Broadcast更新Activity UI

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
}

};
}