java 自定义注解 实现限流

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;


@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
public @interface RateLimiter {
    double permitsPerSecond();
}

import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import org.springframework.stereotype.Component;


import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;


@Aspect
@Component
public class RateLimiterAspect {


    private static final AtomicInteger counter = new AtomicInteger(0);


    @Around("@annotation(rateLimiter)")
    public Object around(ProceedingJoinPoint joinPoint, RateLimiter rateLimiter) throws Throwable {
        double permitsPerSecond = rateLimiter.permitsPerSecond();
        long interval = (long) (1000 / permitsPerSecond);
        long currentTime = System.currentTimeMillis();
        long lastTime = currentTime - interval;


        while (true) {
            int currentCounter = counter.get();
            if (currentCounter > 0 && currentTime - lastTime < interval) {
                Thread.sleep(interval - (currentTime - lastTime));
                currentTime = System.currentTimeMillis();
            } else {
                if (counter.compareAndSet(currentCounter, currentCounter + 1)) {
                    lastTime = currentTime;
                    break;
                }
            }
        }


        return joinPoint.proceed();
    }
}

public class MyService {


    @RateLimiter(permitsPerSecond = 2) // 每秒允许2个请求
    public void myMethod() {
        // 业务逻辑
    }
}