Android：AlarmManager陷阱

Intent i = new Intent(AlarmReciever.ACTION_WAKEUP);
i.putExtra(AlarmDao.ID_COLUMN, a.getId());
PendingIntent pendingIntent = PendingIntent.getBroadcast(
                        context, a.getId(), i, PendingIntent.FLAG_CANCEL_CURRENT);      
Calendar cal = a.getNextAlarm();
if(cal!=null){
    AlarmManager alarmManager = (AlarmManager)
                         context.getSystemService(context.ALARM_SERVICE);
    alarmManager.set(AlarmManager.RTC_WAKEUP, cal.getTimeInMillis(), pendingIntent);
    if(toast) showToast(context, cal);
}

context.startService(wakePlayer);
context.startActivity(wakeWindow);