使用AOP与自定义注解实现限流

@Target(ElementType.METHOD)  
@Retention(RetentionPolicy.RUNTIME)  
public @interface RateLimit {  
    // 限流标识  
    String key() default "";  
  
    // 限制次数  
    int limit();  
  
    // 时间窗口（秒）  
    int window();  
}

@Aspect  
@Component  
public class RateLimitAspect {  
  
    @Resource  
    private StringRedisTemplate redisTemplate;  
  
    @Around("@annotation(rateLimit)")  
    public Object limit(ProceedingJoinPoint joinPoint, RateLimit rateLimit) {  
        String key = buildKey(joinPoint, rateLimit);  
        int limit = rateLimit.limit();  
        int window = rateLimit.window();  
  
        Long count = redisTemplate.opsForValue().increment(key);  
        if (count == 1) {  
            // 第一次访问，设置过期时间  
            redisTemplate.expire(key, Duration.ofSeconds(window));  
        }  
  
        if (count != null && count > limit) {  
            // 限流后如何处理则根据实际情况来 比如这里可以抛出异常终止请求
        }  
  
        return joinPoint.proceed();  
    }  
  
    private String buildKey(ProceedingJoinPoint joinPoint, RateLimit rateLimit) {  
        // 可根据实际情况 如用户ID 用户IP等拼接
        String prefix = "rate_limit:";  
        return prefix + rateLimit.key();  
    }  
}

@GetMapping("/test")
@RateLimit(key = "test", limit = 5, window = 60)
public String test() {
    return "OK";
}