android UI界面更新之通知与服务结…

网上看到的，实际操作了下，例子代码如下。加深对BroadcastReceiver与Service理解

package org.yihu;
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.TextView;public class UIDemoActivity  extends Activity {
     public static final int CMD_STOP_SERVICE = 0;
     Button btnStart;//开始服务Button对象应用
     Button btnStop;//停止服务Button对象应用
     TextView tv;//TextView对象应用
     DataReceiver dataReceiver;//BroadcastReceiver对象
     @Override
  public void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.main);//设置显示的屏幕
      btnStart = (Button)findViewById(R.id.btnStart);
      btnStop = (Button)findViewById(R.id.btnStop);
      tv = (TextView)findViewById(R.id.tv);
     
      btnStart.setOnClickListener(new OnClickListener() {              
                 @Override
                 public void onClick(View v) {
                    
 //                        Intent myIntent = new Intent(Sample_3_6.this, MyService.class);
 //                        startService(myIntent);//发送Intent启动Service
                        
                         Intent intent = new Intent();
                        
                         intent.setAction("org.yihu.UIService");
                         startService(intent);
                 }
       });
      btnStop.setOnClickListener(new OnClickListener() {
                 @Override
                 public void onClick(View v) {
                         Intent myIntent = new Intent();//创建Intent对象
                         myIntent.setAction("org.yihu.cmdReceiver");
                         myIntent.putExtra("cmd", CMD_STOP_SERVICE);
                         sendBroadcast(myIntent);//发送广播
                 }
      });
  }       
  private class DataReceiver extends BroadcastReceiver{//继承自BroadcastReceiver的子类
         @Override
         public void onReceive(Context context, Intent intent) {
             double data = intent.getDoubleExtra("data", 0);
             tv.setText("Service的数据为:"+data);                       
         }               
  }
     @Override
     protected void onStart() {
         dataReceiver = new DataReceiver();
         IntentFilter filter = new IntentFilter();//创建IntentFilter对象
         filter.addAction("org.yihu.Sample_3_6");
         registerReceiver(dataReceiver, filter);//注册Broadcast Receiver
         super.onStart();
     }
     @Override
     protected void onStop() {
         unregisterReceiver(dataReceiver);//取消注册Broadcast Receiver
         super.onStop();
    }


package org.yihu;
import android.app.Service;
 import android.content.BroadcastReceiver;
 import android.content.Context;
 import android.content.Intent;
 import android.content.IntentFilter;
 import android.os.IBinder;
 import android.util.Log;public class MyService extends Service{
     CommandReceiver cmdReceiver;
     boolean flag;
     @Override
     public void onCreate() {
      Log.v("Myservice", "onCreate()...");
         flag = true;
         cmdReceiver = new CommandReceiver();
         super.onCreate();
     }
     @Override
     public IBinder onBind(Intent intent) {
      Log.v("Myservice", "IBinder()...");
         return null;
     }
     @Override
     public int onStartCommand(Intent intent, int flags, int startId) {
      Log.v("Myservice", "onStartCommand()...");
      
         IntentFilter filter = new IntentFilter();
         filter.addAction("org.yihu.cmdReceiver");
         registerReceiver(cmdReceiver, filter);//注册Broadcast Receiver
        
         doJob();//调用方法启动线程
         return super.onStartCommand(intent, flags, startId);
     }
     //方法：
     public void doJob(){
         new Thread(){
             public void run(){
                 while(flag){
                     try{//睡眠一段时间
                             Thread.sleep(1000);
                     }
                     catch(Exception e){
                             e.printStackTrace();
                     }
                     Intent intent = new Intent();//创建Intent对象
                     intent.setAction("org.yihu.Sample_3_6");
                     intent.putExtra("data", Math.random());
                     sendBroadcast(intent);//发送广播
                 }                               
             }
                
         }.start();
     }       
     private class CommandReceiver extends BroadcastReceiver{
         @Override
         public void onReceive(Context context, Intent intent) {
             int cmd = intent.getIntExtra("cmd", -1);
             if(cmd == UIDemoActivity.CMD_STOP_SERVICE){//如果发来的消息是停止服务                               
                 flag = false;//停止线程
                 stopSelf();//停止服务
             }
         }               
     }
     @Override
     public void onDestroy() {//重写onDestroy方法
         this.unregisterReceiver(cmdReceiver);//取消注册的CommandReceiver
         super.onDestroy();
     }       }

mail.xml
<?xml version="1.0" encoding="utf-8"?>
 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
     android:orientation="vertical"
     android:layout_width="fill_parent"
     android:layout_height="fill_parent"
     >
  <Button 
   android:id="@+id/btnStart"
      android:layout_width="fill_parent"
      android:layout_height="wrap_content"
      android:text="start service"
      />
  <Button 
   android:id="@+id/btnStop"
      android:layout_width="fill_parent"
      android:layout_height="wrap_content"
      android:text="stop service"
      />
  <TextView 
   android:id="@+id/tv"
      android:layout_width="fill_parent"
      android:layout_height="wrap_content"
      />
 </LinearLayout>
小结: android广播原理
1.定义BroadcastReceiver扩展类DataReceiver,实现onReceive方法.

 private class DataReceiver extends BroadcastReceiver{//继承自BroadcastReceiver的子类
         @Override
         public void onReceive(Context context, Intent intent) {
             double data = intent.getDoubleExtra("data", 0);
             tv.setText("Service的数据为:"+data);                       
         }               
  }2. 注册广播接收者。注意 "org.yihu.Sample_3_6"广播身份标识，接收时通过此来区分不同广播
       dataReceiver = new DataReceiver();
         IntentFilter filter = new IntentFilter();//创建IntentFilter对象
         filter.addAction("org.yihu.Sample_3_6");
        
3.发送广播. 
   Intent intent = new Intent();//创建Intent对象
     intent.setAction("org.yihu.Sample_3_6");
     intent.putExtra("data", Math.random());
     sendBroadcast(intent);//发送广播

4.广播不用后记得注销

   unregisterReceiver(dataReceiver);//取消注册Broadcast Receiver