Spring Boot使用Redisson实现滑动窗口限流的项目实践

   public boolean allowRequest(String requestKey) {
        // 定义一个时间窗口为1分钟
        long windowSize = Duration.ofMinutes(1).toSeconds();

        // 定义时间窗口内请求阈值为100
        long limit = 100;

        // 当前时间戳
        long currentTime = System.currentTimeMillis();

        // 窗口开始时间为当前时间戳 - 窗口大小
        long windowStart = currentTime - windowSize * 1000;

        // 删除当前窗口开始之前的所有数据
        Jedis.zremrangeByScore(requestKey, "0", String.valueOf(windowStart));

        // 计算当前窗口内的请求总数
        long count = Jedis.zcard(requestKey);

        if (count < limit) {
            // 如果允许访问，则将当前请求加到窗口内
            Jedis.zadd(requestKey, currentTime, String.valueOf(currentTime));
            return true;
        }
        return false;
    }
}

import jakarta.servlet.FilterChain;
import jakarta.servlet.ServletException;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
import java.io.IOException;
import org.redisson.api.RRateLimiter;
import org.redisson.api.RateIntervalUnit;
import org.redisson.api.RateType;
import org.redisson.api.RedissonClient;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.http.HttpStatus;
import org.springframework.web.filter.OncePerRequestFilter;

public class RateLimiterFilter extends OncePerRequestFilter {

    private final Logger log = LoggerFactory.getLogger(RateLimiterFilter.class);

    private static final String RATE_LIMIT_KEY = "rateLimit:yourApiKey";
    private static final int MAX_REQUESTS_PER_MINUTE = 10;

    private final RedissonClient redissonClient;

    public RateLimiterFilter(RedissonClient redissonClient) {
        this.redissonClient = redissonClient;
    }
    
    @Override
    protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain)
        throws ServletException, IOException {
        RRateLimiter rateLimiter = redissonClient.getRateLimiter(RATE_LIMIT_KEY);
        // rateLimiter.trySetRate就是设置限流参数，RateType有两种，OVERALL是全局限流 ，PER_CLIENT是单Client限流（可以认为就是单机限流），这里我们只讨论全局模式。
        // 而后面三个参数的作用就是设置在多长时间窗口内（rateInterval+IntervalUnit），许可总量不超过多少（rate）
        // 上面代码中我设置的值就是1分钟内总许可数不超过10个
        rateLimiter.trySetRate(RateType.OVERALL, MAX_REQUESTS_PER_MINUTE, 1, RateIntervalUnit.MINUTES);
        // 调用rateLimiter的tryAcquire()或者acquire()方法即可获取许可
        if (!rateLimiter.tryAcquire()) {
            
            String path = request.getRequestURI().substring(request.getContextPath().length());
            log.error("当前请求触发限流策略，请求: {} 已经被限流.", path);

            response.setStatus(HttpStatus.TOO_MANY_REQUESTS.value());
            response.getWriter().write("Too many requests!");
            return;
        }
        filterChain.doFilter(request, response);
    }
}