public class FixedWindowRateLimiter {
    Logger logger = LoggerFactory.getLogger(FixedWindowRateLimiter.class);
    //時(shí)間窗口大小，單位毫秒
    long windowSize;
    //允許通過(guò)的請(qǐng)求數(shù)
    int maxRequestCount;
    //當(dāng)前窗口通過(guò)的請(qǐng)求數(shù)
    AtomicInteger counter = new AtomicInteger(0);
    //窗口右邊界
    long windowBorder;
    public FixedWindowRateLimiter(long windowSize, int maxRequestCount) {
        this.windowSize = windowSize;
        this.maxRequestCount = maxRequestCount;
        this.windowBorder = System.currentTimeMillis() + windowSize;
    }
    public synchronized boolean tryAcquire() {
        long currentTime = System.currentTimeMillis();
        if (windowBorder < currentTime) {
            logger.info("window reset");
            do {
                windowBorder += windowSize;
            } while (windowBorder < currentTime);
            counter = new AtomicInteger(0);
        }

        if (counter.intValue() < maxRequestCount) {
            counter.incrementAndGet();
            logger.info("tryAcquire success");
            return true;
        } else {
            logger.info("tryAcquire fail");
            return false;
        }
    }
}

public class SlidingWindowRateLimiter {
    Logger logger = LoggerFactory.getLogger(FixedWindowRateLimiter.class);
    //時(shí)間窗口大小，單位毫秒
    long windowSize;
    //分片窗口數(shù)
    int shardNum;
    //允許通過(guò)的請(qǐng)求數(shù)
    int maxRequestCount;
    //各個(gè)窗口內(nèi)請(qǐng)求計(jì)數(shù)
    int[] shardRequestCount;
    //請(qǐng)求總數(shù)
    int totalCount;
    //當(dāng)前窗口下標(biāo)
    int shardId;
    //每個(gè)小窗口大小，毫秒
    long tinyWindowSize;
    //窗口右邊界
    long windowBorder;

    public SlidingWindowRateLimiter(long windowSize, int shardNum, int maxRequestCount) {
        this.windowSize = windowSize;
        this.shardNum = shardNum;
        this.maxRequestCount = maxRequestCount;
        this.shardRequestCount = new int[shardNum];
        this.tinyWindowSize = windowSize / shardNum;
        this.windowBorder = System.currentTimeMillis();
    }
    public synchronized boolean tryAcquire() {
        long currentTime = System.currentTimeMillis();
        if (windowBorder < currentTime) {
            logger.info("window reset");
            do {
                shardId = (++shardId) % shardNum;
                totalCount -= shardRequestCount[shardId];
                shardRequestCount[shardId] = 0;
                windowBorder += tinyWindowSize;
            } while (windowBorder < currentTime);
        }

        if (totalCount < maxRequestCount) {
            logger.info("tryAcquire success:{}", shardId);
            shardRequestCount[shardId]++;
            totalCount++;
            return true;
        } else {
            logger.info("tryAcquire fail");
            return false;
        }
    }
}

public class LeakyBucketRateLimiter {
    Logger logger = LoggerFactory.getLogger(LeakyBucketRateLimiter.class);
    //桶的容量
    int capacity;
    //桶中現(xiàn)存水量
    AtomicInteger water = new AtomicInteger();
    //開(kāi)始漏水時(shí)間
    long leakTimestamp;
    //水流出的速率，即每秒允許通過(guò)的請(qǐng)求數(shù)
    int leakRate;

    public LeakyBucketRateLimiter(int capacity, int leakRate) {
        this.capacity = capacity;
        this.leakRate = leakRate;
    }

    public synchronized boolean tryAcquire() {
        //桶中沒(méi)有水， 重新開(kāi)始計(jì)算
        if (water.get() == 0) {
            logger.info("start leaking");
            leakTimestamp = System.currentTimeMillis();
            water.incrementAndGet();
            return water.get() < capacity;
        }
        //先漏水，計(jì)算剩余水量
        long currentTime = System.currentTimeMillis();
        int leakedWater = (int) ((currentTime - leakTimestamp) / 1000 * leakRate);
        logger.info("lastTime:{}, currentTime:{}. LeakedWater:{}", leakTimestamp, currentTime, leakedWater);
        //可能時(shí)間不足，則先不漏水
        if (leakedWater != 0) {
            int leftWater = water.get() - leakedWater;
            //可能水已漏光。設(shè)為0
            water.set(Math.max(0, leftWater));
            leakTimestamp = System.currentTimeMillis();
        }
        logger.info("剩余容量:{}", capacity - water.get());
        if (water.get() < capacity) {
            logger.info("tryAcquire sucess");
            water.incrementAndGet();
            return true;
        } else {
            logger.info("tryAcquire fail");
            return false;
        }
    }
}

<dependency>
    <groupId>com.google.guava</groupId>
    <artifactId>guava</artifactId>
    <version>32.1.3-jre</version>
</dependency>

@Test
public void acquireTest() {
    //每秒固定生成5個(gè)令牌
    RateLimiter rateLimiter = RateLimiter.create(5);
    for (int i = 0; i < 10; i++) {
        double time = rateLimiter.acquire();
        logger.info("等待時(shí)間：{}s", time);
    }
}

  @Test
    public void acquireSmoothly() {
        RateLimiter rateLimiter = RateLimiter.create(5, 3, TimeUnit.SECONDS);
        long startTimeStamp = System.currentTimeMillis();
        for (int i = 0; i < 15; i++) {
            double time = rateLimiter.acquire();
            logger.info("等待時(shí)間:{}s, 總時(shí)間:{}ms", time, System.currentTimeMillis() - startTimeStamp);
        }
    }

@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.METHOD})
@Documented
public @interface Limit {
    // 資源主鍵
    String key() default "";
    //最多訪問(wèn)次數(shù),代表請(qǐng)求總數(shù)量
    double permitsPerSeconds();
    // 時(shí)間：即timeout時(shí)間內(nèi),只允許有permitsPerSeconds個(gè)請(qǐng)求總數(shù)量訪問(wèn)，超過(guò)的將被限制不能訪問(wèn)
    long timeout();
    //時(shí)間類型
    TimeUnit timeUnit() default TimeUnit.MILLISECONDS;

    //提示信息
    String msg() default "系統(tǒng)繁忙,請(qǐng)稍后重試";
}

@Aspect
@Component
public class LimitAspect {
    Logger logger = LoggerFactory.getLogger(LimitAspect.class);
    private final Map<String, RateLimiter> limitMap = Maps.newConcurrentMap();

???@Around("@annotation(com.alibaba.xxx.xxx.annotation.Limit)")
    public Object around(ProceedingJoinPoint joinPoint) throws Throwable {
        MethodSignature signature = (MethodSignature) joinPoint.getSignature();
        Method method = signature.getMethod();
        //拿limit的注解
        Limit limit = method.getAnnotation(Limit.class);
        if (limit != null) {
            // key作用：不同的接口，不同的流量控制
            String key = limit.key();
            RateLimiter rateLimiter;
            //驗(yàn)證緩存是否有命中key
            if (!limitMap.containsKey(key)) {
                //創(chuàng)建令牌桶
                rateLimiter = RateLimiter.create(limit.permitsPerSeconds());
                limitMap.put(key, rateLimiter);
                logger.info("新建了令牌桶={},容量={}", key, limit.permitsPerSeconds());
            }
            rateLimiter = limitMap.get(key);
            //拿令牌
            boolean acquire = rateLimiter.tryAcquire(limit.timeout(), limit.timeUnit());
            //拿不到令牌，直接返回異常信息
            if (!acquire) {
                logger.debug("令牌桶={},獲取令牌失敗", key);
                throw new RuntimeException(limit.msg());
            }
        }
        return joinPoint.proceed();
    }
}

@Limit(key = "query",
permitsPerSeconds = 1,
timeout = 1,
msg = "觸發(fā)接口限流，請(qǐng)重試")

{
    "timestamp": "2023-12-07 11:21:47",
    "status": 500,
    "error": "Internal Server Error",
    "path": "/table/query"
}

{
    "code": -1,
    "message": "觸發(fā)接口限流，請(qǐng)重試",
    "data": "fail"
}