<dependency>
    <groupId>com.google.guava</groupId>
    <artifactId>guava</artifactId>
    <version>30.1-jre</version>
</dependency>

@Slf4j
@RestController
@RequestMapping("/limit")
public class LimitController {
    /**
     * 限流策略 ： 1秒鐘2個(gè)請(qǐng)求
     */
    private final RateLimiter limiter = RateLimiter.create(2.0);

    private DateTimeFormatter dtf = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");

    @GetMapping("/test1")
    public String testLimiter() {
        //500毫秒內(nèi)，沒拿到令牌，就直接進(jìn)入服務(wù)降級(jí)
        boolean tryAcquire = limiter.tryAcquire(500, TimeUnit.MILLISECONDS);

        if (!tryAcquire) {
            log.warn("進(jìn)入服務(wù)降級(jí)，時(shí)間{}", LocalDateTime.now().format(dtf));
            return "當(dāng)前排隊(duì)人數(shù)較多，請(qǐng)稍后再試！";
        }

        log.info("獲取令牌成功，時(shí)間{}", LocalDateTime.now().format(dtf));
        return "請(qǐng)求成功";
    }
}

WARN  LimitController:35 - 進(jìn)入服務(wù)降級(jí)，時(shí)間2021-09-25 21:39:37
WARN  LimitController:35 - 進(jìn)入服務(wù)降級(jí)，時(shí)間2021-09-25 21:39:37
INFO  LimitController:39 - 獲取令牌成功，時(shí)間2021-09-25 21:39:37
WARN  LimitController:35 - 進(jìn)入服務(wù)降級(jí)，時(shí)間2021-09-25 21:39:37
WARN  LimitController:35 - 進(jìn)入服務(wù)降級(jí)，時(shí)間2021-09-25 21:39:37
INFO  LimitController:39 - 獲取令牌成功，時(shí)間2021-09-25 21:39:37

WARN  LimitController:35 - 進(jìn)入服務(wù)降級(jí)，時(shí)間2021-09-25 21:39:38
INFO  LimitController:39 - 獲取令牌成功，時(shí)間2021-09-25 21:39:38
WARN  LimitController:35 - 進(jìn)入服務(wù)降級(jí)，時(shí)間2021-09-25 21:39:38
INFO  LimitController:39 - 獲取令牌成功，時(shí)間2021-09-25 21:39:38

<dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-aop</artifactId>
</dependency>

@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.METHOD})
@Documented
public @interface Limit {
    /**
     * 資源的key,唯一
     * 作用：不同的接口，不同的流量控制
     */
    String key() default "";

    /**
     * 最多的訪問限制次數(shù)
     */
    double permitsPerSecond () ;

    /**
     * 獲取令牌最大等待時(shí)間
     */
    long timeout();

    /**
     * 獲取令牌最大等待時(shí)間,單位(例:分鐘/秒/毫秒) 默認(rèn):毫秒
     */
    TimeUnit timeunit() default TimeUnit.MILLISECONDS;

    /**
     * 得不到令牌的提示語(yǔ)
     */
    String msg() default "系統(tǒng)繁忙,請(qǐng)稍后再試.";
}

@Slf4j
@Aspect
@Component
public class LimitAop {
    /**
     * 不同的接口，不同的流量控制
     * map的key為 Limiter.key
     */
    private final Map<String, RateLimiter> limitMap = Maps.newConcurrentMap();

    @Around("@annotation(com.jianzh5.blog.limit.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 = null;
            //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.permitsPerSecond());
                limitMap.put(key, rateLimiter);
                log.info("新建了令牌桶={}，容量={}",key,limit.permitsPerSecond());
            }
            rateLimiter = limitMap.get(key);
            // 拿令牌
            boolean acquire = rateLimiter.tryAcquire(limit.timeout(), limit.timeunit());
            // 拿不到命令，直接返回異常提示
            if (!acquire) {
                log.debug("令牌桶={}，獲取令牌失敗",key);
                this.responseFail(limit.msg());
                return null;
            }
        }
        return joinPoint.proceed();
    }

    /**
     * 直接向前端拋出異常
     * @param msg 提示信息
     */
    private void responseFail(String msg)  {
        HttpServletResponse response=((ServletRequestAttributes) RequestContextHolder.getRequestAttributes()).getResponse();
        ResultData<Object> resultData = ResultData.fail(ReturnCode.LIMIT_ERROR.getCode(), msg);
        WebUtils.writeJson(response,resultData);
    }
}

@Slf4j
@RestController
@RequestMapping("/limit")
public class LimitController {
    
    @GetMapping("/test2")
    @Limit(key = "limit2", permitsPerSecond = 1, timeout = 500, timeunit = TimeUnit.MILLISECONDS,msg = "當(dāng)前排隊(duì)人數(shù)較多，請(qǐng)稍后再試！")
    public String limit2() {
        log.info("令牌桶l(fā)imit2獲取令牌成功");
        return "ok";
    }


    @GetMapping("/test3")
    @Limit(key = "limit3", permitsPerSecond = 2, timeout = 500, timeunit = TimeUnit.MILLISECONDS,msg = "系統(tǒng)繁忙，請(qǐng)稍后再試！")
    public String limit3() {
        log.info("令牌桶l(fā)imit3獲取令牌成功");
        return "ok";
    }
}

{"status":100,"message":"操作成功","data":"ok","timestamp":1632579377104}

{"status":2001,"message":"系統(tǒng)繁忙，請(qǐng)稍后再試！","data":null,"timestamp":1632579332177}