前言

近期一个老项目出现了接口幂等性 校验问题，前端加了按钮置灰，

依然被人拉着接口参数一顿输出，还是重复调用了接口，小陈及时赶到现场，通过复制粘贴，完成了后端接口幂等性调用校验。

以前写过一篇关于接口简单限流防止重复调用的，但是跟该篇还是不一样的，该篇的角度是接口和参数整体一致才当做重复。

简单限流：  （Redis使用系列） Springboot 使用redis实现接口Api限流 十

该篇内容：

实现接口调用的幂等性校验

方案 ：自定义注解+redis+拦截器+MD5 实现

草图，意会（用户标识不是必要，看业务场景是针对个人还是只针对接口&参数）：

话不多说，开始实战。

PS： 前排提醒，如果你还不知道怎么springboot整合redis，可以先去看下redis使用系列的 一、二。

（Redis使用系列） SpringBoot 中对应2.0.x版本的Redis配置 一

（Redis使用系列） SpringBoot中Redis的RedisConfig 二

正文

自定义注解 怎么玩的 ：      

①标记哪个接口需要进行幂等性拦截        

②每个接口可以要求幂等性范围时间不一样，举例：可以2秒内，可以3秒内，时间自己传        

③ 一旦触发了，提示语可以不同 ，举例：VIP的接口，普通用户的接口，提示语不一样（开玩笑）

效果：

实战开始：

核心三件套

注解、拦截器、拦截器配置

① RepeatDaMie.java

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

/**
 * @Author: JCccc
 * @Date: 2022-6-13 9:04
 * @Description:  自定义注解,防止重复提交
 */
@Target({ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
public @interface RepeatDaMie {

    /**
     * 时间ms限制
     */
    public int second() default 1;

    /**
     * 提示消息
     */
    public String describe() default "重复提交了,兄弟";
    
}

②ApiRepeatInterceptor.java

import com.example.repeatdemo.annotation.RepeatDaMie;
import com.example.repeatdemo.util.ContextUtil;
import com.example.repeatdemo.util.Md5Encrypt;
import com.example.repeatdemo.util.RedisUtils;
import com.example.repeatdemo.wrapper.CustomHttpServletRequestWrapper;
import com.fasterxml.jackson.databind.ObjectMapper;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Component;
import org.springframework.web.method.HandlerMethod;
import org.springframework.web.servlet.HandlerInterceptor;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.Objects;

/**
 * @Author: JCccc
 * @Date: 2022-6-15 9:11
 * @Description: 接口幂等性校验拦截器
 */
@Component
public class ApiRepeatInterceptor implements HandlerInterceptor {

    private final Logger log = LoggerFactory.getLogger(this.getClass());

    private static final String POST="POST";
    private static final String GET="GET";
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        try {
            if (handler instanceof HandlerMethod) {
                HandlerMethod handlerMethod = (HandlerMethod) handler;
                // 获取RepeatDaMie注解
                RepeatDaMie repeatDaMie = handlerMethod.getMethodAnnotation(RepeatDaMie.class);
                if (null==repeatDaMie) {
                    return true;
                }
                //限制的时间范围
                int seconds = repeatDaMie.second();
                //这个用户唯一标识，可以自己细微调整，是userId还是token还是sessionId还是不需要
                String userUniqueKey = request.getHeader("userUniqueKey");
                String method = request.getMethod();
                String apiParams = "";
                if (GET.equals(method)){
                    log.info("GET请求来了");
                    apiParams = new ObjectMapper().writeValueAsString(request.getParameterMap());
                }else if (POST.equals(method)){
                    log.info("POST请求来了");
                    CustomHttpServletRequestWrapper wrapper = (CustomHttpServletRequestWrapper) request;
                    apiParams = wrapper.getBody();
                }
               log.info("当前参数是：{}",apiParams);
                // 存储key
                String keyRepeatDaMie = Md5Encrypt.md5(userUniqueKey+request.getServletPath()+apiParams) ;
                RedisUtils redisUtils = ContextUtil.getBean(RedisUtils.class);
                if (Objects.nonNull(redisUtils.get(keyRepeatDaMie))){
                   log.info("重复请求了，重复请求了，拦截了");
                   returnData(response,repeatDaMie.describe());
                   return false;
               }else {
                    redisUtils.setWithTime(keyRepeatDaMie, true,seconds);
               }

            }
            return true;
        } catch (Exception e) {
            log.warn("请求出现异常,errorMsg={}",e.getMessage());
            returnData(response,"请求出现异常");
            return false;
        }
        return true;
    }

    public void returnData(HttpServletResponse response,String msg) throws IOException {
        response.setCharacterEncoding("UTF-8");
        response.setContentType("application/json; charset=utf-8");
        ObjectMapper objectMapper = new ObjectMapper();
        //这里传提示语可以改成自己项目的返回数据封装的类
        response.getWriter().println(objectMapper.writeValueAsString(msg));
        return;
    }

}

③ WebConfig.java

import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

/**
 * @Author: JCccc
 * @Date: 2022-6-15 9:24
 * @Description:
 */
@Configuration
public class WebConfig implements WebMvcConfigurer {

    
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(new ApiRepeatInterceptor()).addPathPatterns("/**");
    }
}

工具类三件套

①ContextUtil.java

import org.springframework.beans.BeansException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.stereotype.Component;
/**
 * @Author: JCccc
 * @Date: 2022-6-15 9:24
 * @Description:
 */
@Component
public final class ContextUtil implements ApplicationContextAware {
    protected static ApplicationContext applicationContext ;
    @Override
    public void setApplicationContext(ApplicationContext arg0) throws BeansException {
        if (applicationContext == null) {
            applicationContext = arg0;
        }
    }
    public static Object getBean(String name) {
        //name表示其他要注入的注解name名
        return applicationContext.getBean(name);
    }
    /**
     * 拿到ApplicationContext对象实例后就可以手动获取Bean的注入实例对象
     */
    public static <T> T getBean(Class<T> clazz) {
        return applicationContext.getBean(clazz);
    }
}

②Md5Encrypt.java

import java.io.UnsupportedEncodingException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

/**
 * @Author: JCccc
 * @CreateTime: 2018-10-30
 * @Description:
 */
public class Md5Encrypt {

    private static final char[] DIGITS = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a',
            'b', 'c', 'd', 'e', 'f'};

    /**
     * 对字符串进行MD5加密
     *
     * @param text 明文
     * @return 密文
     */
    public static String md5(String text) {
        MessageDigest msgDigest = null;

        try {
            msgDigest = MessageDigest.getInstance("MD5");
        } catch (NoSuchAlgorithmException e) {
            throw new IllegalStateException("System doesn't support MD5 algorithm.");
        }

        try {
            // 注意该接口是按照指定编码形式签名
            msgDigest.update(text.getBytes("UTF-8"));

        } catch (UnsupportedEncodingException e) {

            throw new IllegalStateException("System doesn't support your  EncodingException.");

        }

        byte[] bytes = msgDigest.digest();

        String md5Str = new String(encodeHex(bytes));

        return md5Str;
    }

    private static char[] encodeHex(byte[] data) {

        int l = data.length;

        char[] out = new char[l << 1];
        // two characters form the hex value.
        for (int i = 0, j = 0; i < l; i++) {
            out[j++] = DIGITS[(0xF0 & data[i]) >>> 4];
            out[j++] = DIGITS[0x0F & data[i]];
        }

        return out;
    }
}

③RedisUtils.java

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.redis.core.*;
import org.springframework.stereotype.Component;
import java.io.Serializable;
import java.util.List;
import java.util.Set;
import java.util.concurrent.TimeUnit;

@Component
public class RedisUtils {

    @Autowired
    private RedisTemplate redisTemplate;

    /**
     * 写入String型 [ 键，值]
     *
     * @param key
     * @param value
     * @return
     */

    public boolean set(final String key, Object value) {
        boolean result = false;
        try {
            ValueOperations<Serializable, Object> operations = redisTemplate.opsForValue();
            operations.set(key, value);
            result = true;
        } catch (Exception e) {
            e.printStackTrace();
        }
        return result;

    }


    /**
     * 写入String型,顺便带有过期时间 [ 键，值]
     *
     * @param key
     * @param value
     * @return
     */

    public boolean setWithTime(final String key, Object value,int seconds) {
        boolean result = false;
        try {

            ValueOperations<Serializable, Object> operations = redisTemplate.opsForValue();
            operations.set(key, value,seconds, TimeUnit.SECONDS);
            result = true;
        } catch (Exception e) {
            e.printStackTrace();
        }
        return result;

    }


    /**
     * 批量删除对应的value
     *
     * @param keys
     */

    public void remove(final String... keys) {
        for (String key : keys) {
            remove(key);
        }
    }

    /**
     * 批量删除key
     *
     * @param pattern
     */

    public void removePattern(final String pattern) {
        Set<Serializable> keys = redisTemplate.keys(pattern);
        if (keys.size() > 0)
            redisTemplate.delete(keys);
    }

    /**
     * 删除对应的value
     *
     * @param key
     */

    public void remove(final String key) {
        if (exists(key)) {
            redisTemplate.delete(key);
        }
    }

    /**
     * 判断缓存中是否有对应的value
     *
     * @param key
     * @return
     */

    public boolean exists(final String key) {
        return redisTemplate.hasKey(key);
    }

    /**
     * 读取缓存
     *
     * @param key
     * @return
     */

    public Object get(final String key) {
        Object result = null;
        ValueOperations<Serializable, Object> operations = redisTemplate.opsForValue();
        result = operations.get(key);
        return result;
    }

    /**
     * 哈希 添加
     * hash 一个键值(key->value)对集合
     *
     * @param key
     * @param hashKey
     * @param value
     */

    public void hmSet(String key, Object hashKey, Object value) {

        HashOperations<String, Object, Object> hash = redisTemplate.opsForHash();

        hash.put(key, hashKey, value);

    }

    /**
     * Hash获取数据
     *
     * @param key
     * @param hashKey
     * @return
     */

    public Object hmGet(String key, Object hashKey) {
        HashOperations<String, Object, Object> hash = redisTemplate.opsForHash();
        return hash.get(key, hashKey);

    }

    /**
     * 列表添加
     * list:lpush key value1
     *
     * @param k
     * @param v
     */

    public void lPush(String k, Object v) {
        ListOperations<String, Object> list = redisTemplate.opsForList();
        list.rightPush(k, v);
    }

    /**
     * 列表List获取
     * lrange： key 0 10 (读取的个数 从0开始 读取到下标为10 的数据)
     *
     * @param k
     * @param l
     * @param l1
     * @return
     */

    public List<Object> lRange(String k, long l, long l1) {
        ListOperations<String, Object> list = redisTemplate.opsForList();
        return list.range(k, l, l1);
    }

    /**
     * Set集合添加
     *
     * @param key
     * @param value
     */

    public void add(String key, Object value) {
        SetOperations<String, Object> set = redisTemplate.opsForSet();
        set.add(key, value);
    }

    /**
     * Set 集合获取
     *
     * @param key
     * @return
     */

    public Set<Object> setMembers(String key) {

        SetOperations<String, Object> set = redisTemplate.opsForSet();

        return set.members(key);

    }

    /**
     * Sorted set :有序集合添加
     *
     * @param key
     * @param value
     * @param scoure
     */

    public void zAdd(String key, Object value, double scoure) {
        ZSetOperations<String, Object> zset = redisTemplate.opsForZSet();
        zset.add(key, value, scoure);
    }

    /**
     * Sorted set:有序集合获取
     *
     * @param key
     * @param scoure
     * @param scoure1
     * @return
     */

    public Set<Object> rangeByScore(String key, double scoure, double scoure1) {

        ZSetOperations<String, Object> zset = redisTemplate.opsForZSet();

        return zset.rangeByScore(key, scoure, scoure1);

    }

    /**
     * 根据key获取Set中的所有值
     *
     * @param key 键
     * @return
     */

    public Set<Integer> sGet(String key) {
        try {
            return redisTemplate.opsForSet().members(key);
        } catch (Exception e) {
            e.printStackTrace();
            return null;
        }
    }

    /**
     * 根据value从一个set中查询,是否存在
     *
     * @param key   键
     * @param value 值
     * @return true 存在 false不存在
     */

    public boolean sHasKey(String key, Object value) {
        try {
            return redisTemplate.opsForSet().isMember(key, value);
        } catch (Exception e) {
            e.printStackTrace();
            return false;
        }
    }

}

REDIS配置类

RedisConfig.java

import com.fasterxml.jackson.annotation.JsonAutoDetect;
import com.fasterxml.jackson.annotation.PropertyAccessor;
import com.fasterxml.jackson.databind.ObjectMapper;
import org.springframework.cache.CacheManager;
import org.springframework.cache.annotation.EnableCaching;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.redis.cache.RedisCacheConfiguration;
import org.springframework.data.redis.cache.RedisCacheManager;
import org.springframework.data.redis.connection.RedisConnectionFactory;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.serializer.Jackson2JsonRedisSerializer;
import org.springframework.data.redis.serializer.RedisSerializationContext;
import org.springframework.data.redis.serializer.StringRedisSerializer;
import static org.springframework.data.redis.cache.RedisCacheConfiguration.defaultCacheConfig;

/**
 * @Author: JCccc
 * @CreateTime: 2018-09-11
 * @Description:
 */
@Configuration
@EnableCaching
public class RedisConfig {
    @Bean
    public CacheManager cacheManager(RedisConnectionFactory connectionFactory) {
        RedisCacheConfiguration cacheConfiguration =
                defaultCacheConfig()
                        .disableCachingNullValues()
                        .serializeValuesWith(RedisSerializationContext.SerializationPair.fromSerializer(new Jackson2JsonRedisSerializer(Object.class)));
        return RedisCacheManager.builder(connectionFactory).cacheDefaults(cacheConfiguration).build();
    }

    @Bean
    public RedisTemplate<String, Object> redisTemplate(RedisConnectionFactory factory) {
        RedisTemplate<String, Object> redisTemplate = new RedisTemplate<>();
        redisTemplate.setConnectionFactory(factory);
        Jackson2JsonRedisSerializer jackson2JsonRedisSerializer = new Jackson2JsonRedisSerializer(Object.class);
        ObjectMapper om = new ObjectMapper();
        om.setVisibility(PropertyAccessor.ALL, JsonAutoDetect.Visibility.ANY);
        om.enableDefaultTyping(ObjectMapper.DefaultTyping.NON_FINAL);
        jackson2JsonRedisSerializer.setObjectMapper(om);
        //序列化设置 ，这样为了存储操作对象时正常显示的数据，也能正常存储和获取
        redisTemplate.setKeySerializer(new StringRedisSerializer());
        redisTemplate.setValueSerializer(jackson2JsonRedisSerializer);
        redisTemplate.setHashKeySerializer(new StringRedisSerializer());
        redisTemplate.setHashValueSerializer(jackson2JsonRedisSerializer);
        return redisTemplate;
    }
    @Bean
    public StringRedisTemplate stringRedisTemplate(RedisConnectionFactory factory) {
        StringRedisTemplate stringRedisTemplate = new StringRedisTemplate();
        stringRedisTemplate.setConnectionFactory(factory);
        return stringRedisTemplate;
    }

}

处理流数据三件套

【文章】流数据只能读一次的三件套，以后直接复制粘贴使用

最后写测试接口，看看效果（一个POST，一个GET）：
故意把时间放大，1000秒内重复调用，符合我们拦截规则的都会被拦截。

TestController.java

import com.example.repeatdemo.dto.PayOrderApply;
import com.example.repeatdemo.annotation.RepeatDaMie;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.web.bind.annotation.*;

/**
 * @Author: JCccc
 * @Date: 2022-6-05 9:44
 * @Description:
 */
@RestController
public class TestController {
    private final Logger log = LoggerFactory.getLogger(this.getClass());

    @RepeatDaMie(second = 1000,describe = "尊敬的客户,您慢点")
    @PostMapping(value = "/doPost")
    @ResponseBody
    public void test(@RequestBody PayOrderApply payOrderApply) {
        log.info("Controller POST请求:"+payOrderApply.toString());
    }

    @RepeatDaMie(second = 1000,describe = "大哥,你冷静点")
    @GetMapping(value = "/doGet")
    @ResponseBody
    public void doGet( PayOrderApply payOrderApply) {
        log.info("Controller GET请求:"+payOrderApply.toString());
    }

}

PayOrderApply.java

/**
 * @Author: JCccc
 * @Date: 2022-6-12 9:46
 * @Description:
 */
public class PayOrderApply {

    private String sn;
    private Long amount;
    private String proCode;

    public String getSn() {
        return sn;
    }

    public void setSn(String sn) {
        this.sn = sn;
    }

    public Long getAmount() {
        return amount;
    }

    public void setAmount(Long amount) {
        this.amount = amount;
    }

    public String getProCode() {
        return proCode;
    }

    public void setProCode(String proCode) {
        this.proCode = proCode;
    }

    @Override
    public String toString() {
        return "PayOrderApply{" +
                "sn='" + sn + '\'' +
                ", amount=" + amount +
                ", proCode='" + proCode + '\'' +
                '}';
    }
}

redis生成了值：

好了，该篇就到这吧、

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