public boolean tryAcquire(int permits, long timeout, TimeUnit unit) {
  //尝试获取资源最多等待时间
  long timeoutMicros = max(unit.toMicros(timeout), 0);
  //检查获取资源数目是否正确
  checkPermits(permits);
  long microsToWait;
  //加锁
  synchronized (mutex()) {
   //当前时间
   long nowMicros = stopwatch.readMicros();
   //判断是否可以在timeout时间内获取资源
   if (!canAcquire(nowMicros, timeoutMicros)) {
    return false;
   } else {
    //可获取资源，对资源进行重新计算，并返回当前线程需要休眠时间
    microsToWait = reserveAndGetWaitLength(permits, nowMicros);
   }
  }
  //休眠
  stopwatch.sleepMicrosUninterruptibly(microsToWait);
  return true;
 }

 private boolean canAcquire(long nowMicros, long timeoutMicros) {
  //最早可获取资源时间-等待时间<=当前时间 方可获取资源
  return queryEarliestAvailable(nowMicros) - timeoutMicros <= nowMicros;
}

final long reserveAndGetWaitLength(int permits, long nowMicros) {
  //获取下次可获取时间
  long momentAvailable = reserveEarliestAvailable(permits, nowMicros);
  //计算当前线程需要休眠时间
  return max(momentAvailable - nowMicros, 0);
}

 final long reserveEarliestAvailable(int requiredPermits, long nowMicros) {
  //重新计算桶内令牌数storedPermits
  resync(nowMicros);
  long returnValue = nextFreeTicketMicros;
  //本次消耗的令牌数
  double storedPermitsToSpend = min(requiredPermits, this.storedPermits);
  //重新计算下次可获取时间nextFreeTicketMicros
  double freshPermits = requiredPermits - storedPermitsToSpend;
  long waitMicros =
    storedPermitsToWaitTime(this.storedPermits, storedPermitsToSpend)
      + (long) (freshPermits * stableIntervalMicros);

  this.nextFreeTicketMicros = LongMath.saturatedAdd(nextFreeTicketMicros, waitMicros);
  //减少桶内令牌数
  this.storedPermits -= storedPermitsToSpend;
  return returnValue;
 }

public SimpleRateLimitInterceptor(int rate) {
    if (rate > 0)
      globalRateLimiter = RateLimiter.create(rate);
    else
      throw new RuntimeException("rate must greater than zero");
}

public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
   if (!globalRateLimiter.tryAcquire()) {
     LoggerUtil.log(request.getRequestURI()+"请求超过限流器速率");
     return false;
   }
   return true;
 }

  <mvc:interceptors>
    <!--限流拦截器-->
    <mvc:interceptor>
      <mvc:mapping path="/**"/>
      <bean class="limit.SimpleRateLimitInterceptor">
        <constructor-arg index="0" value="${totalRate}"/>
      </bean>
    </mvc:interceptor>
  </mvc:interceptors>

<mvc:interceptor>
      <mvc:mapping path="/**"/>

      <bean class="limit.RateLimitInterceptor">
        <!--单url限流-->
        <property name="urlProperties">
          <props>
            <prop key="/get/{id}">1</prop>
            <prop key="/post">2</prop>
          </props>
        </property>

      </bean>
</mvc:interceptor>

//当前请求路径
String lookupPath = urlPathHelper.getLookupPathForRequest(request);
//迭代所有url表达式对应的PatternsRequestCondition
for (PatternsRequestCondition patternsRequestCondition : urlRateMap.keySet()) {
  //进行匹配
  List<String> matches = patternsRequestCondition.getMatchingPatterns(lookupPath);
  if (!matches.isEmpty()) {
    //匹配成功的则获取对应限流器的令牌
    if (urlRateMap.get(patternsRequestCondition).tryAcquire()) {
      LoggerUtil.log(lookupPath + " 请求匹配到" + Joiner.on(",").join(patternsRequestCondition.getPatterns()) + "限流器");
    } else {
      //获取令牌失败
      LoggerUtil.log(lookupPath + " 请求超过" + Joiner.on(",").join(patternsRequestCondition.getPatterns()) + "限流器速率");
      return false;
    }

  }
}