@Override
	public long getCount(long when){
		Long recWhen = when - (when % granularity);
		AtomicLong times = counters.get(recWhen);
		return times == null ? 0 : times.longValue(); 
	}
@ Override public long getCount ( long when ) { Long recWhen = when - ( when % granularity ) ; AtomicLong times = counters . get ( recWhen ) ; return times == null ? 0 : times . longValue ( ) ; }
获取在某时刻的计数值。
@param when	时刻
@return		统计数