Service详解

/**
 *  后台执行的定时任务
 */
public class LongRunningService extends Service {

    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }

    @Override
    public int onStartCommand(Intent intent,int flags,int startId) {
    
        new Thread(){
            public void run() {
                Log.i("TAG","LongRunningService exec at " + new Date().toString());
            };
        }.start();
        
        //获取Alarm管理对象
        AlarmManager manager = (AlarmManager)getSystemService(ALARM_SERVICE);
        
        //设置执行的时间间隔
        long triggerAtTime = SystemClock.elapsedRealtime() + 5 * 1000; 
        
        //获取一个能够执行广播的 PendingIntent。 这样当定时任务被触发的时候，广播接收器的 
         onReceive()方法就可以得到执行。
        Intent intent2 = new Intent(this,AlarmReceiver.class);
        PendingIntent pendingIntent = PendingIntent.getBroadcast(this, 0, intent2, 0);
        
        //设置一个定时任务
        manager.set(AlarmManager.ELAPSED_REALTIME_WAKEUP, triggerAtTime, pendingIntent);
        return super.onStartCommand(intent,flags,startId);
    }
}

public class AlarmReceiver extends BroadcastReceiver {
    @Override
    public void onReceive(Context context,Intent intent) {
        Intent intent2 = new Intent(context, LongRunningService.class);
        context.startService(intent2);
    }
}

/**
 *  前台服务
 */
public class ForegroundService extends Service {

    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }
    
    @Override
    public void onCreate() {
        Intent intent = new Intent(this,MainActivity.class);
        PendingIntent pendingIntent = PendingIntent.getActivity(this,0,intent,0);
        
        Notification nf = new Notification(R.drawable.p1,"有一条通知",System.currentTimeMillis());
        nf.setLatestEventInfo(this,"这是通知的标题","这是通知的内容",pendingIntent);
        nf.flags = Notification.FLAG_AUTO_CANCEL;
        //调用这个方法将服务变为前台服务，并在系统通知栏显示出来
        startForeground(1,nf);
        
        super.onCreate();
    }
}