@Aspect
@Component
public class RateLimiterAop {// 创建map，key是URL，value是令牌，同一个请求就覆盖上一个值private static ConcurrentHashMap<String, RateLimiter> rateLimiterMap = new ConcurrentHashMap<String, RateLimiter>();//切入点，拦截com.lzh.demo包下的所有的public类和方法@Pointcut("execution(public * com.lzh.demo.*(..))")public void rlAop() {} //使用AOP环绕通知判断拦截所有springmvc的请求，判断请求方法上是否存在ExtRateLimiter @Around("rlAop()")public Object doBefore(ProceedingJoinPoint proceedingJoinPoint) throws Throwable {//判断是否存在@ExtRateLimiter注解MethodSignature signature = (MethodSignature) proceedingJoinPoint.getSignature();// 使用Java反射技术获取方法上是否有@ExtRateLimiter注解类ExtRateLimiter extRateLimiter = signature.getMethod().getDeclaredAnnotation(ExtRateLimiter.class);if (extRateLimiter == null) {// 直接进入正常方法Object proceed = proceedingJoinPoint.proceed();return proceed;}// 获取配置的速率，默认值double value = extRateLimiter.value();// 获取等待令牌等待时间long timeOut = extRateLimiter.timeOut();RateLimiter rateLimiter = getRateLimiter(value, timeOut);// 如果没有在有效期内获得token，那么就调用降级方法boolean tryAcquire = rateLimiter.tryAcquire(timeOut, TimeUnit.MILLISECONDS);if (!tryAcquire) {serviceDowng();return null;}// 获取到令牌,直接执行Object proceed = proceedingJoinPoint.proceed();return proceed;}// 获取RateLimiter对象，保证每个请求都是单例的，比如很多的同一个pay请求可以共用一个ratelimiter，　　 //但是如果是order请求，那么就必须再创建一个ratelimiter，根据URL进行判断private RateLimiter getRateLimiter(double value, long timeOut) {// 获取当前URIServletRequestAttributes attributes = (ServletRequestAttributes) RequestContextHolder.getRequestAttributes();HttpServletRequest request = attributes.getRequest();String requestURI = request.getRequestURI();RateLimiter rateLimiter = null;if (!rateLimiterMap.containsKey(requestURI)) {// 如果没有检测到URI，那么创建一个新的ratelimiterrateLimiter = RateLimiter.create(value); // 独立线程
            rateLimiterMap.put(requestURI, rateLimiter);} else {// 能够在map中检测到URL就添加到map中，相同的请求在同一个ratemiliter中rateLimiter = rateLimiterMap.get(requestURI);}return rateLimiter;}// 服务降级private void serviceDowng() throws IOException {　　　　　// 获取响应ServletRequestAttributes attributes = (ServletRequestAttributes) RequestContextHolder.getRequestAttributes();HttpServletResponse response = attributes.getResponse();response.setHeader("Content-type", "text/html;charset=UTF-8");PrintWriter writer = response.getWriter();try {writer.println("执行降级方法,亲,服务器忙！请稍后重试!");} catch (Exception e) {} finally {writer.close();}}
}

@Target(value = ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
public @interface ExtRateLimiter {　　// 以秒为单位的速率往桶中存令牌double value();// 规定的毫秒内如果没有得到令牌那么就走降级服务long timeOut();
}

package com.lzh.demo

// 测试代码@RequestMapping("/myOrder")
@ExtRateLimiter(value = 10.0, timeOut = 500)
public String myOrder() throws InterruptedException {System.out.println("myOrder");return "SUCCESS";
}