用法：

在需要限流的接口controller方法上添加@Limit

@Limit(key = "login", period = 60, count = 20, name = "登录接口", prefix = "limit")

原理：

使用自定义注解，在切面中获取限流器的信息，配合redis的lua脚本，实现如果在规定时间内的请求次数超过限制，就不继续执行controller方法

详细实现：

注解：

package com.jswdwsx.common.annotation;


import com.jswdwsx.common.enums.LimitType;

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
public @interface Limit {

    // 资源名称，用于描述接口功能
    String name() default "";

    // 资源 key
    String key() default "";

    // key prefix
    String prefix() default "";

    // 时间的，单位秒
    int period();

    // 限制访问次数
    int count();

    // 限制类型
    LimitType limitType() default LimitType.CUSTOMER;
}

package com.jswdwsx.common.enums;

public enum LimitType {
    // 传统类型
    CUSTOMER,
    // 根据 IP 限制
    IP;
}

切面：

/**
 * 接口限流
 */
@Slf4j
@Aspect
@Component
public class LimitAspect {

    private final RedisTemplate<String, Serializable> limitRedisTemplate;

    @Autowired
    public LimitAspect(RedisTemplate<String, Serializable> limitRedisTemplate) {
        this.limitRedisTemplate = limitRedisTemplate;
    }

    @Pointcut("@annotation(com.jswdwsx.common.annotation.Limit)")
    public void pointcut() {
        // do nothing
    }

    @Around("pointcut()")
    public Object around(ProceedingJoinPoint point) throws Throwable {
        HttpServletRequest request = ((ServletRequestAttributes) Objects.requireNonNull(RequestContextHolder.getRequestAttributes())).getRequest();

        MethodSignature signature = (MethodSignature) point.getSignature();
        Method method = signature.getMethod();
        Limit limitAnnotation = method.getAnnotation(Limit.class);
        LimitType limitType = limitAnnotation.limitType();
        String name = limitAnnotation.name();
        String key;
        String ip = IPUtil.getIpAddr(request);
        int limitPeriod = limitAnnotation.period();
        int limitCount = limitAnnotation.count();
        switch (limitType) {
            case IP:
                key = ip;
                break;
            case CUSTOMER:
                key = limitAnnotation.key();
                break;
            default:
                key = StringUtils.upperCase(method.getName());
        }
        ImmutableList<String> keys = ImmutableList.of(StringUtils.join(limitAnnotation.prefix() + "_", key, ip));
        String luaScript = buildLuaScript();
        RedisScript<Number> redisScript = new DefaultRedisScript<>(luaScript, Number.class);
        Number count = limitRedisTemplate.execute(redisScript, keys, limitCount, limitPeriod);
        log.info("IP:{} 第 {} 次访问key为 {}，描述为 [{}] 的接口", ip, count, keys, name);
        if (count != null && count.intValue() <= limitCount) {
            return point.proceed();
        } else {
            throw new LimitAccessException("接口访问超出频率限制,请在" + limitPeriod + "秒后重试");
        }
    }

    /**
     * 限流脚本
     * 调用的时候不超过阈值，则直接返回并执行计算器自加。
     *
     * @return lua脚本
     */
    private String buildLuaScript() {
        return "local c" +
                "\nc = redis.call('get',KEYS[1])" +
                "\nif c and tonumber(c) > tonumber(ARGV[1]) then" +
                "\nreturn c;" +
                "\nend" +
                "\nc = redis.call('incr',KEYS[1])" +
                "\nif tonumber(c) == 1 then" +
                "\nredis.call('expire',KEYS[1],ARGV[2])" +
                "\nend" +
                "\nreturn c;";
    }

}