利用Redisson封装一个限流工具并解析限流原理

import redis.clients.jedis.Jedis;

public class RateLimiter {
    private final Jedis jedis;
    private final String keyPrefix;
    private final int limit;
    private final int seconds;

    public RateLimiter(Jedis jedis, String keyPrefix, int limit, int seconds) {
        this.jedis = jedis;
        this.keyPrefix = keyPrefix;
        this.limit = limit;
        this.seconds = seconds;
    }

    public boolean isAllowed(String userId) {
        String key = keyPrefix + ":" + userId;
        long now = System.currentTimeMillis() / 1000;
        long count = jedis.incr(key);
        if (count == 1) {
            jedis.expire(key, seconds); // 如果是第一次访问，设置键的过期时间
        }
        // 如果当前次数超过限制，则不允许访问，并删除该键以便下次重新计数
        if (count > limit) {
            jedis.del(key);
            return false;
        }
        // 如果没有超过限制，则允许访问
        return true;
    }
}