@RestController
public class GuavaRate {
    @ZRateLimiter(rate = 5,timeOut = 100)
    @RequestMapping("/find2")
    public void tryAcquire(){
    }
}

@Target(value = ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface ZRateLimiter {

    //往令牌桶放入令牌的速率
    double rate();

    //获取令牌桶的超时时间
    long timeOut() default 0;
}

@Aspect
@Component
public class RateLimiterAspect {

    @Autowired
    private HttpServletResponse response;

    private RateLimiter rateLimiter=RateLimiter.create(50);

//    @Pointcut("execution(public * com.aop.demo.aop.*.*(..))")
    @Pointcut("@annotation(com.aop.demo.GUAVA.ZRateLimiter)")
    public void pointcut(){}

    @Around("pointcut()")
    public Object RateLimiter2(ProceedingJoinPoint joinPoint)throws Throwable{
       //通过切点获取签名
       MethodSignature signature= (MethodSignature)joinPoint.getSignature();
        ZRateLimiter zRateLimiter
                = signature.getMethod().getDeclaredAnnotation(ZRateLimiter.class);
       if(zRateLimiter==null){
           //没有加限流的注解的话，就直接正常执行业逻辑，不参与接口的限流保护
           return joinPoint.proceed();
       }

        double rate = zRateLimiter.rate();//获取注解上的参数
        long timeOut = zRateLimiter.timeOut();//获取令牌等待时间

        rateLimiter.setRate(rate);
        boolean tryAcquire = rateLimiter.tryAcquire(timeOut, TimeUnit.MILLISECONDS);
        if(!tryAcquire){
            System.out.println("服务繁忙，请稍后再试");
            return "服务繁忙，请稍后再试";
        }
        //获取到令牌
        System.out.println("success");
        //执行业务代码
        return joinPoint.proceed();
    }



}

//解释Guava限流包下的一个限流的算法
		RateLimiter rateLimiter=RateLimiter.create(5);//create（5）表示的是一秒发出5个令牌,每200毫秒一个令牌
        System.out.println(rateLimiter.acquire(1));
        System.out.println(rateLimiter.acquire(1));
        System.out.println(rateLimiter.acquire(1));
        System.out.println(rateLimiter.acquire(1));
        
		//执行的结果是
		0.0
		0.198121
		0.192586
		0.198563

RateLimiter rateLimiter=RateLimiter.create(5);//create（5）表示的是一秒发出5个令牌,每200毫秒一个令牌
		//突然接受一个大量的请求
        System.out.println(rateLimiter.acquire(100));
        System.out.println(rateLimiter.acquire(1));
        System.out.println(rateLimiter.acquire(1));
        System.out.println(rateLimiter.acquire(1));
        //执行的结果
        0.0
		19.99783
		0.192275
		0.197414
		//解释。第一次执行100个请求的时候，需要时间为0，但是第二次限流保护的时候，执行的时间为约20秒，就是所有的时间都累		  计到第二次限流保护