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：

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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:

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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 } }; }