<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個請求
?????*/
????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，沒拿到令牌，就直接進入服務降級
????????boolean?tryAcquire?=?limiter.tryAcquire(500,?TimeUnit.MILLISECONDS);
????????if?(!tryAcquire)?{
????????????log.warn("進入服務降級，時間{}",?LocalDateTime.now().format(dtf));
????????????return?"當前排隊人數(shù)較多，請稍后再試！";
????????}
????????log.info("獲取令牌成功，時間{}",?LocalDateTime.now().format(dtf));
????????return?"請求成功";
????}
}

<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間
?????*/
????long?timeout();
????/**
?????*?獲取令牌最大等待時間,單位(例:分鐘/秒/毫秒)?默認:毫秒
?????*/
????TimeUnit?timeunit()?default?TimeUnit.MILLISECONDS;
????/**
?????*?得不到令牌的提示語
?????*/
????String?msg()?default?"系統(tǒng)繁忙,請稍后再試.";
}

@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?=?"當前排隊人數(shù)較多，請稍后再試！")
????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，請稍后再試！","data":null,"timestamp":1632579332177}