Android Service和广播联合更新UI的例子

在Android中，异步更新UI，通常我们会选用Handler启动线程，或者sendMessage的方式，那么利用Service和广播也可以更新UI的，例子如下：我们建立一个Service：

package com.andy
import android.app.Service;//引入相关包
import android.content.BroadcastReceiver;//引入相关包
import android.content.Context;//引入相关包
import android.content.Intent;//引入相关包
import android.content.IntentFilter;//引入相关包
import android.os.IBinder;//引入相关包
//继承自Service的子类
public class MyService extends Service{
       CommandReceiver cmdReceiver;
       boolean flag;
       @Override
       public void onCreate(){//重写onCreate方法
              flag = true;
              cmdReceiver = newCommandReceiver();
             super.onCreate();
       }
       @Override
       public IBinder onBind(Intent intent){//重写onBind方法
              // TODO Auto-generated methodstub
              return null;
       }
       @Override
       public int onStartCommand(Intent intent, intflags, int startId) {//重写onStartCommand方法
              IntentFilter filter = newIntentFilter();//创建IntentFilter对象
             filter.addAction("wyf.wpf.MyService");
              registerReceiver(cmdReceiver,filter);//注册Broadcast Receiver
             doJob();//调用方法启动线程
              returnsuper.onStartCommand(intent, flags, startId);
       }
       //方法：
       public void doJob(){
              newThread(){
                     publicvoid run(){
                           while(flag){
                                  try{//睡眠一段时间
                                        Thread.sleep(1000);
                                  }
                                  catch(Exceptione){
                                        e.printStackTrace();
                                  }
                                  Intent intent = newIntent();//创建Intent对象
                                 intent.setAction("wyf.wpf.Sample_3_6");
                                  intent.putExtra("data",Math.random());
                                 sendBroadcast(intent);//发送广播
                           }
                    }

              }.start();
       }
       private class CommandReceiver extendsBroadcastReceiver{//继承自BroadcastReceiver的子类
              @Override
              public void onReceive(Contextcontext, Intent intent) {//重写onReceive方法
                     int cmd =intent.getIntExtra("cmd", -1);//获取Extra信息
                     if(cmd ==Sample_3_6.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();
       }
}

建立一个activity

package com.andy;//声明包语句
import android.app.Activity;//引入相关包
import android.content.BroadcastReceiver;//引入相关包
import android.content.Context;//引入相关包
import android.content.Intent;//引入相关包
import android.content.IntentFilter;//引入相关包
import android.os.Bundle;//引入相关包
import android.view.View;//引入相关包
import android.view.View.OnClickListener;//引入相关包
import android.widget.Button;//引入相关包
import android.widget.TextView;//引入相关包
//继承自Activity的子类
public class Sample_3_6 extends Activity {
       public static final int CMD_STOP_SERVICE =0;
       ButtonbtnStart;//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
       DataReceiverdataReceiver;//BroadcastReceiver对象
       @Override
    public void onCreate(BundlesavedInstanceState) {//重写onCreate方法
       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(newOnClickListener() {//为按钮添加点击事件监听
                    @Override
                     publicvoid onClick(View v) {//重写onClick方法
                           Intent myIntent = new Intent(Sample_3_6.this,wyf.wpf.MyService.class);
                          Sample_3_6.this.startService(myIntent);//发送Intent启动Service
                    }
              });
       btnStop.setOnClickListener(newOnClickListener() {//为按钮添加点击事件监听
                    @Override
                     publicvoid onClick(View v) {//重写onClick方法
                           Intent myIntent = newIntent();//创建Intent对象
                          myIntent.setAction("wyf.wpf.MyService");
                           myIntent.putExtra("cmd",CMD_STOP_SERVICE);
                           sendBroadcast(myIntent);//发送广播
                    }
              });
    }
       private class DataReceiver extendsBroadcastReceiver{//继承自BroadcastReceiver的子类
              @Override
              public void onReceive(Contextcontext, Intent intent) {//重写onReceive方法
                     doubledata = intent.getDoubleExtra("data", 0);
                    tv.setText("Service的数据为:"+data);
              }
       }
       @Override
       protected void onStart(){//重写onStart方法
              dataReceiver = newDataReceiver();
              IntentFilter filter = newIntentFilter();//创建IntentFilter对象
             filter.addAction("wyf.wpf.Sample_3_6");
             registerReceiver(dataReceiver, filter);//注册BroadcastReceiver
             super.onStart();
       }
       @Override
       protected void onStop(){//重写onStop方法
             unregisterReceiver(dataReceiver);//取消注册BroadcastReceiver
             super.onStop();
       }

}