//操作：发送一个广播，广播接收后Toast提示定时操作完成   Intent intent =new Intent(Main.this, alarmreceiver.class);
intent.setAction("short");
PendingIntent sender= PendingIntent.getBroadcast(Main.this, 0, intent, 0);
//设定一个五秒后的时间
Calendar calendar=Calendar.getInstance();
calendar.setTimeInMillis(System.currentTimeMillis());
calendar.add(Calendar.SECOND, 5);
AlarmManager alarm=(AlarmManager)getSystemService(ALARM_SERVICE);
alarm.set(AlarmManager.RTC_WAKEUP, calendar.getTimeInMillis(), sender);
//或者以下面方式简化
//alarm.set(AlarmManager.RTC_WAKEUP, System.currentTimeMillis()+5*1000, sender);
Toast.makeText(Main.this, "五秒后alarm开启", Toast.LENGTH_LONG).show();

public static class alarmreceiver extends BroadcastReceiver{
    @Override
    public void onReceive(Context context, Intent intent) {
      // TODO Auto-generated method stub
      if(intent.getAction().equals("short")){
        Toast.makeText(context, "short alarm", Toast.LENGTH_LONG).show();
      }else{
        Toast.makeText(context, "repeating alarm",            Toast.LENGTH_LONG).show();
      }
    }
}

Intent intent =new Intent(Main.this, alarmreceiver.class);
intent.setAction("repeating");
PendingIntent sender=PendingIntent
.getBroadcast(Main.this, 0, intent, 0);
//开始时间
long firstime=SystemClock.elapsedRealtime();
AlarmManager am=(AlarmManager)getSystemService(ALARM_SERVICE);　　//5秒一个周期，不停的发送广播
am.setRepeating(AlarmManager.ELAPSED_REALTIME_WAKEUP, firstime, 5*1000, sender);

Intent intent =new Intent(Main.this, alarmreceiver.class);
intent.setAction("repeating");
PendingIntent sender=PendingIntent.getBroadcast(Main.this, 0, intent, 0);
AlarmManager alarm=(AlarmManager)getSystemService(ALARM_SERVICE);
alarm.cancel(sender);