android中的定时任务AlarmManager

private void requestUpdateFeatureBook() {
    AlarmManager am = (AlarmManager)getContext().getSystemService(Context.ALARM_SERVICE);

    PendingIntent sender = PendingIntent.getBroadcast(getContext(), 0,new Intent(Config.UPDATE_FEATUREBOOK), 0);
    am.cancel(sender);
    am.setRepeating(AlarmManager.RTC, System.currentTimeMillis()/*Config.FEATUREBOOK_UPDATE_TIME*/,Config.FEATUREBOOK_UPDATE_TIME, sender);