code: public static boolean safeSleep(Number millis) {
  		long millisLong = millis.longValue();
  		long done = 0;
  		while (done < millisLong) {
  			long before = System.currentTimeMillis();
  			if (false == sleep(millisLong - done)) {
  				return false;
  			}
  			long after = System.currentTimeMillis();
  			done += (after - before);
  		}
  		return true;
  	}
docs: 考虑{@link Thread#sleep(long)}方法有可能时间不足给定毫秒数，此方法保证sleep时间不小于给定的毫秒数
  
  @see ThreadUtil#sleep(Number)
  @param millis 给定的sleep时间
  @return 被中断返回false，否则true