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怎么使用AOP+redis+lua做限流

需求

公司里使用OneByOne的方式删除数据，为了防止一段时间内删除数据过多，让我这边做一个接口限流，超过一定阈值后报异常，终止删除操作。

实现方式

创建自定义注解 @limit 让使用者在需要的地方配置 count(一定时间内最多访问次数)、 period(给定的时间范围)，也就是访问频率。然后通过LimitInterceptor拦截方法的请求， 通过 redis+lua 脚本的方式，控制访问频率。

源码

Limit 注解

用于配置方法的访问频率count、period

import javax.validation.constraints.Min;
import java.lang.annotation.*;
@Target({ElementType.METHOD, ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Inherited
@Documented
public @interface Limit {
    /**
     * key
     */
    String key() default "";
    /**
     * Key的前缀
     */
    String prefix() default "";
    /**
     * 一定时间内最多访问次数
     */
    @Min(1)
    int count();
    /**
     * 给定的时间范围 单位(秒)
     */
    @Min(1)
    int period();
    /**
     * 限流的类型(用户自定义key或者请求ip)
     */
    LimitType limitType() default LimitType.CUSTOMER;
}

LimitKey

用于标记参数，作为redis key值的一部分

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
@Target(ElementType.PARAMETER)
@Retention(RetentionPolicy.RUNTIME)
public @interface LimitKey {
}

LimitType

枚举，redis key值的类型，支持自定义key和ip、methodName中获取key

public enum LimitType {
    /**
     * 自定义key
     */
    CUSTOMER,
    /**
     * 请求者IP
     */
    IP,
    /**
     * 方法名称
     */
    METHOD_NAME;
}

RedisLimiterHelper

初始化一个限流用到的redisTemplate Bean

import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.serializer.GenericJackson2JsonRedisSerializer;
import org.springframework.data.redis.serializer.StringRedisSerializer;
import java.io.Serializable;
@Configuration
public class RedisLimiterHelper {
    @Bean
    public RedisTemplate<String, Serializable> limitRedisTemplate(@Qualifier("defaultStringRedisTemplate") StringRedisTemplate redisTemplate) {
        RedisTemplate<String, Serializable> template = new RedisTemplate<String, Serializable>();
        template.setKeySerializer(new StringRedisSerializer());
        template.setValueSerializer(new GenericJackson2JsonRedisSerializer());
        template.setConnectionFactory(redisTemplate.getConnectionFactory());
        return template;
    }
}

LimitInterceptor

使用 aop 的方式来拦截请求，控制访问频率

import com.google.common.collect.ImmutableList;
import com.yxt.qida.api.bean.service.xxv2.openapi.anno.Limit;
import com.yxt.qida.api.bean.service.xxv2.openapi.anno.LimitKey;
import com.yxt.qida.api.bean.service.xxv2.openapi.anno.LimitType;
import lombok.extern.slf4j.Slf4j;
import org.apache.commons.lang3.ArrayUtils;
import org.apache.commons.lang3.StringUtils;
import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.reflect.MethodSignature;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.data.redis.core.script.DefaultRedisScript;
import org.springframework.data.redis.core.script.RedisScript;
import org.springframework.web.context.request.RequestContextHolder;
import org.springframework.web.context.request.ServletRequestAttributes;
import javax.servlet.http.HttpServletRequest;
import java.io.Serializable;
import java.lang.annotation.Annotation;
import java.lang.reflect.Method;
@Slf4j
@Aspect
@Configuration
public class LimitInterceptor {
    private static final String UNKNOWN = "unknown";
    private final RedisTemplate<String, Serializable> limitRedisTemplate;
    @Autowired
    public LimitInterceptor(RedisTemplate<String, Serializable> limitRedisTemplate) {
        this.limitRedisTemplate = limitRedisTemplate;
    }
    @Around("execution(public * *(..)) && @annotation(com.yxt.qida.api.bean.service.xxv2.openapi.anno.Limit)")
    public Object interceptor(ProceedingJoinPoint pjp) {
        MethodSignature signature = (MethodSignature) pjp.getSignature();
        Method method = signature.getMethod();
        Limit limitAnnotation = method.getAnnotation(Limit.class);
        LimitType limitType = limitAnnotation.limitType();
        int limitPeriod = limitAnnotation.period();
        int limitCount = limitAnnotation.count();
        /**
         * 根据限流类型获取不同的key ,如果不传我们会以方法名作为key
         */
        String key;
        switch (limitType) {
            case IP:
                key = getIpAddress();
                break;
            case CUSTOMER:
                key = limitAnnotation.key();
                break;
            case METHOD_NAME:
                String methodName = method.getName();
                key = StringUtils.upperCase(methodName);
                break;
            default:
                throw new RuntimeException("limitInterceptor - 无效的枚举值");
        }
        /**
         * 获取注解标注的 key，这个是优先级最高的，会覆盖前面的 key 值
         */
        Object[] args = pjp.getArgs();
        Annotation[][] paramAnnoAry = method.getParameterAnnotations();
        for (Annotation[] item : paramAnnoAry) {
            int paramIndex = ArrayUtils.indexOf(paramAnnoAry, item);
            for (Annotation anno : item) {
                if (anno instanceof LimitKey) {
                    Object arg = args[paramIndex];
                    if (arg instanceof String && StringUtils.isNotBlank((String) arg)) {
                        key = (String) arg;
                        break;
                    }
                }
            }
        }
        if (StringUtils.isBlank(key)) {
            throw new RuntimeException("limitInterceptor - key值不能为空");
        }
        String prefix = limitAnnotation.prefix();
        String[] keyAry = StringUtils.isBlank(prefix) ? new String[]{"limit", key} : new String[]{"limit", prefix, key};
        ImmutableList<String> keys = ImmutableList.of(StringUtils.join(keyAry, "-"));
        try {
            String luaScript = buildLuaScript();
            RedisScript<Number> redisScript = new DefaultRedisScript<Number>(luaScript, Number.class);
            Number count = limitRedisTemplate.execute(redisScript, keys, limitCount, limitPeriod);
            if (count != null && count.intValue() <= limitCount) {
                return pjp.proceed();
            } else {
                String classPath = method.getDeclaringClass().getName() + "." + method.getName();
                throw new RuntimeException("limitInterceptor - 限流被触发："
                        + "class:" + classPath
                        + ", keys:" + keys
                        + ", limitcount:" + limitCount
                        + ", limitPeriod:" + limitPeriod + "s");
            }
        } catch (Throwable e) {
            if (e instanceof RuntimeException) {
                throw new RuntimeException(e.getLocalizedMessage());
            }
            throw new RuntimeException("limitInterceptor - 限流服务异常");
        }
    }
    /**
     * lua 脚本，为了保证执行 redis 命令的原子性
     */
    public String buildLuaScript() {
        StringBuilder lua = new StringBuilder();
        lua.append("local c");
        lua.append("\nc = redis.call('get',KEYS[1])");
        // 调用不超过最大值，则直接返回
        lua.append("\nif c and tonumber(c) > tonumber(ARGV[1]) then");
        lua.append("\nreturn c;");
        lua.append("\nend");
        // 执行计算器自加
        lua.append("\nc = redis.call('incr',KEYS[1])");
        lua.append("\nif tonumber(c) == 1 then");
        // 从第一次调用开始限流，设置对应键值的过期
        lua.append("\nredis.call('expire',KEYS[1],ARGV[2])");
        lua.append("\nend");
        lua.append("\nreturn c;");
        return lua.toString();
    }
    public String getIpAddress() {
        HttpServletRequest request = ((ServletRequestAttributes) RequestContextHolder.getRequestAttributes()).getRequest();
        String ip = request.getHeader("x-forwarded-for");
        if (ip == null || ip.length() == 0 || UNKNOWN.equalsIgnoreCase(ip)) {
            ip = request.getHeader("Proxy-Client-IP");
        }
        if (ip == null || ip.length() == 0 || UNKNOWN.equalsIgnoreCase(ip)) {
            ip = request.getHeader("WL-Proxy-Client-IP");
        }
        if (ip == null || ip.length() == 0 || UNKNOWN.equalsIgnoreCase(ip)) {
            ip = request.getRemoteAddr();
        }
        return ip;
    }
}

TestService

使用方式示例

    @Limit(period = 10, count = 10)
    public String delUserByUrlTest(@LimitKey String token, String thirdId, String url) throws IOException {
        return "success";
    }

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