BroadcastReceiver的生命周期

 BroadcastReceiver在android中是一特色功能.android系统的很多消息(如系统启动,新短信,来电话等)都通过BroadcastReceiver来分发.BroadcastReceiver的生命周期是短暂的,而且是消息一到达则创建执行完毕就立刻销毁的.为了说明这一点,我通过注册一个Alarm Service每7秒钟触发产生一次BroadcastReceive事件.

 

以下是BroadcastReceive的实现

Java代码

1. protected static final class AlarmReceiver extends BroadcastReceiver{   
2.     public AlarmReceiver()   
3.     {   
4.         //查看类创建的进程id和线程id   
5.         Log.i("AlarmReceiver.AlarmReceiver()", Calendar.getInstance().getTime().toLocaleString());   
6.         Log.i("AlarmReceiver.AlarmReceiver() -> pid", String.valueOf(android.os.Process.myPid()));   
7.         Log.i("AlarmReceiver.AlarmReceiver() -> tid", String.valueOf(android.os.Process.myTid()));   
8.     }   
9.     @Override  
10.     public void onReceive(Context context, Intent intent) {   
11.         // TODO Auto-generated method stub   
12.         Log.i("AlarmReceiver.onReceive()", Calendar.getInstance().getTime().toLocaleString());   
13.     }   
14. }  

protected static final class AlarmReceiver extends BroadcastReceiver{public AlarmReceiver(){//查看类创建的进程id和线程idLog.i("AlarmReceiver.AlarmReceiver()", Calendar.getInstance().getTime().toLocaleString());Log.i("AlarmReceiver.AlarmReceiver() -> pid", String.valueOf(android.os.Process.myPid()));Log.i("AlarmReceiver.AlarmReceiver() -> tid", String.valueOf(android.os.Process.myTid()));}@Overridepublic void onReceive(Context context, Intent intent) {// TODO Auto-generated method stubLog.i("AlarmReceiver.onReceive()", Calendar.getInstance().getTime().toLocaleString());}}

 

通过一个"Start"按钮和一个"Stop"按钮来控制消息.

Java代码

1. public void onClick(View arg0) {   
2.     // TODO Auto-generated method stub   
3.     switch(arg0.getId()){   
4.     case R.id.btnStart:   
5.         Log.i("current pid", String.valueOf(android.os.Process.myPid()));   
6.         Log.i("current tid", String.valueOf(android.os.Process.myTid()));   
7.            
8.         ((AlarmManager)this.getSystemService(Context.ALARM_SERVICE))   
9.             .setRepeating(AlarmManager.RTC_WAKEUP, System.currentTimeMillis(), 7*1000,    
10.                  PendingIntent.getBroadcast(this, 0, new Intent(this,AlarmReceiver.class), 0)   
11.                 );   
12.         break;   
13.     case R.id.btnStop:   
14.         ((AlarmManager)this.getSystemService(Context.ALARM_SERVICE))   
15.             .cancel(PendingIntent.getBroadcast(this, 0, new Intent(this,AlarmReceiver.class), 0));   
16.         break;   
17.     }   
18. }  

public void onClick(View arg0) {// TODO Auto-generated method stubswitch(arg0.getId()){case R.id.btnStart:Log.i("current pid", String.valueOf(android.os.Process.myPid()));Log.i("current tid", String.valueOf(android.os.Process.myTid()));((AlarmManager)this.getSystemService(Context.ALARM_SERVICE)).setRepeating(AlarmManager.RTC_WAKEUP, System.currentTimeMillis(), 7*1000,  PendingIntent.getBroadcast(this, 0, new Intent(this,AlarmReceiver.class), 0));break;case R.id.btnStop:((AlarmManager)this.getSystemService(Context.ALARM_SERVICE)).cancel(PendingIntent.getBroadcast(this, 0, new Intent(this,AlarmReceiver.class), 0));break;}}

 

打开logCat选择I,运行清理掉所有日志点击"Start"按钮

从上图可以看到AlarmReceiver类的实例是每触发一次就新建一次的,而且和程序是在同一个进程同一线程内.