<!-- AOP依賴 -->
<dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-aop</artifactId>
            <version>2.1.5.RELEASE</version>
</dependency>
<!-- Map依賴 -->
<dependency>
            <groupId>net.jodah</groupId>
            <artifactId>expiringmap</artifactId>
            <version>0.5.8</version>
</dependency>

@Documented
@Target(ElementType.METHOD) // 說(shuō)明該注解只能放在方法上面
@Retention(RetentionPolicy.RUNTIME)
public @interface LimitRequest {
    long time() default 6000; // 限制時(shí)間 單位：毫秒
    int count() default 1; // 允許請(qǐng)求的次數(shù)
}

@Aspect
@Component
public class LimitRequestAspect {
 
    private static ConcurrentHashMap<String, ExpiringMap<String, Integer>> book = new ConcurrentHashMap<>();
 
    // 定義切點(diǎn)
    // 讓所有有@LimitRequest注解的方法都執(zhí)行切面方法
    @Pointcut("@annotation(limitRequest)")
    public void excudeService(LimitRequest limitRequest) {
    }
 
    @Around("excudeService(limitRequest)")
    public Object doAround(ProceedingJoinPoint pjp, LimitRequest limitRequest) throws Throwable {
 
        // 獲得request對(duì)象
        RequestAttributes ra = RequestContextHolder.getRequestAttributes();
        ServletRequestAttributes sra = (ServletRequestAttributes) ra;
        HttpServletRequest request = sra.getRequest();
        
        // 獲取Map對(duì)象， 如果沒(méi)有則返回默認(rèn)值
        // 第一個(gè)參數(shù)是key， 第二個(gè)參數(shù)是默認(rèn)值
        ExpiringMap<String, Integer> uc = book.getOrDefault(request.getRequestURI(), ExpiringMap.builder().variableExpiration().build());
        Integer uCount = uc.getOrDefault(request.getRemoteAddr(), 0);
 
 
 
        if (uCount >= limitRequest.count()) { // 超過(guò)次數(shù)，不執(zhí)行目標(biāo)方法
            return "接口請(qǐng)求超過(guò)次數(shù)";
        } else if (uCount == 0){ // 第一次請(qǐng)求時(shí)，設(shè)置有效時(shí)間
//            /** Expires entries based on when they were last accessed */
//            ACCESSED,
//            /** Expires entries based on when they were created */
//            CREATED;
            uc.put(request.getRemoteAddr(), uCount + 1, ExpirationPolicy.CREATED, limitRequest.time(), TimeUnit.MILLISECONDS);
        } else { // 未超過(guò)次數(shù)， 記錄加一
            uc.put(request.getRemoteAddr(), uCount + 1);
        }
        book.put(request.getRequestURI(), uc);
 
        // result的值就是被攔截方法的返回值
        Object result = pjp.proceed();
 
        return result;
    }
 
 
}