你应该设置两个报警管理器。对于第一个设置的触发时间通过计算适当时间的剩余时间（例如上午8:00）。然后你应该在你的第一个警报管理器内创建另一个警报管理器，每个触发15分钟。

you should setup two alarm manager.for the first one set trigger time by calculating the remain time to your appropriate time (for example 8:00 Am). and after that you should create another alarm manager inside of your first alarm manager that will trigger each 15 minutes.

用于设置第一个警报管理器的计算时间使用下面的代码：

for calculate time for set first alarm manager use the code bellow:

Calendar c = Calendar.getInstance(); 
int m = calendar.get(Calendar.MINUTE);
long start = System.currentTimeMillis();
int remain=0;
if (m<15)
{
 remain = 15-m;
}
else if (m<30)
{
 remain = 30-m;
}
else if (m<45)
{
 remain = 45-m;
}
else
{
 remain = 60-m;
}
remain=start + remain*60*1000// convert it to milisecond and plus it to current time;

修改

之后你可以使用下面的代码设置第一个报警管理器：

and after that you can use code bellow to setup first alarm manager:

 AlarmManager am=(AlarmManager)context.getSystemService(Context.ALARM_SERVICE);
    Intent intent = new Intent(context, FirstReceiver.class);
    PendingIntent pi = PendingIntent.getBroadcast(context, 0, intent, 0);
    am.set(AlarmManager.RTC_WAKEUP,remain, pi);

所以现在在你的FirstReceiver课上做类似下面的事情：

so now in your FirstReceiver class do something like bellow:

public class FirstReceiver extends BroadcastReceiver
{
//do what ever you want + code bellow to setup second alarm manager
 Intent intent = new Intent(this, SecAlarm.class);
 PendingIntent pi = PendingIntent.getBroadcast(this, 0, intent, 0);
 AlarmManager am=  (AlarmManager)getSystemService(Context.ALARM_SERVICE);
am.setRepeating(AlarmManager.ELAPSED_REALTIME,SystemClock.elapsedRealtime(),
                15*60*60,pendingIntent);
}