SpringBoot + Redis + 注解 + 拦截器实现接口幂等性校验

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转自：简书作者：wangzaiplus
https://www.jianshu.com/p/6189275403ed

一、概念

幂等性, 通俗的说就是一个接口, 多次发起同一个请求, 必须保证操作只能执行一次
比如:

订单接口, 不能多次创建订单
支付接口, 重复支付同一笔订单只能扣一次钱
支付宝回调接口, 可能会多次回调, 必须处理重复回调
普通表单提交接口, 因为网络超时等原因多次点击提交, 只能成功一次
等等

二、常见解决方案

唯一索引 -- 防止新增脏数据
token机制 -- 防止页面重复提交
悲观锁 -- 获取数据的时候加锁(锁表或锁行)
乐观锁 -- 基于版本号version实现, 在更新数据那一刻校验数据
分布式锁 -- redis(jedis、redisson)或zookeeper实现
状态机 -- 状态变更, 更新数据时判断状态

三、本文实现

本文采用第2种方式实现, 即通过redis + token机制实现接口幂等性校验

四、实现思路

为需要保证幂等性的每一次请求创建一个唯一标识token, 先获取token, 并将此token存入redis, 请求接口时, 将此token放到header或者作为请求参数请求接口, 后端接口判断redis中是否存在此token:

如果存在, 正常处理业务逻辑, 并从redis中删除此token, 那么, 如果是重复请求, 由于token已被删除, 则不能通过校验, 返回请勿重复操作提示
如果不存在, 说明参数不合法或者是重复请求, 返回提示即可

五、项目简介

springboot
redis
@ApiIdempotent注解 + 拦截器对请求进行拦截
@ControllerAdvice全局异常处理
压测工具: jmeter

说明:

本文重点介绍幂等性核心实现, 关于springboot如何集成redis、ServerResponse、ResponseCode等细枝末节不在本文讨论范围之内, 有兴趣的小伙伴可以查看我的Github项目: https://github.com/wangzaiplus/springboot/tree/wxw

六、代码实现

1.pom

<!-- Redis-Jedis --><dependency><groupId>redis.clients</groupId><artifactId>jedis</artifactId><version>2.9.0</version></dependency><!--lombok 本文用到@Slf4j注解, 也可不引用, 自定义log即可--><dependency><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId><version>1.16.10</version></dependency>

2.JedisUtil

package com.wangzaiplus.test.util;import lombok.extern.slf4j.Slf4j;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.stereotype.Component;import redis.clients.jedis.Jedis;import redis.clients.jedis.JedisPool;@Component@Slf4jpublic class JedisUtil {    @Autowired    private JedisPool jedisPool;    private Jedis getJedis() {        return jedisPool.getResource();    }    /**     * 设值     *     * @param key     * @param value     * @return     */    public String set(String key, String value) {        Jedis jedis = null;        try {            jedis = getJedis();            return jedis.set(key, value);        } catch (Exception e) {            log.error("set key:{} value:{} error", key, value, e);            return null;        } finally {            close(jedis);        }    }    /**     * 设值     *     * @param key     * @param value     * @param expireTime 过期时间, 单位: s     * @return     */    public String set(String key, String value, int expireTime) {        Jedis jedis = null;        try {            jedis = getJedis();            return jedis.setex(key, expireTime, value);        } catch (Exception e) {            log.error("set key:{} value:{} expireTime:{} error", key, value, expireTime, e);            return null;        } finally {            close(jedis);        }    }    /**     * 取值     *     * @param key     * @return     */    public String get(String key) {        Jedis jedis = null;        try {            jedis = getJedis();            return jedis.get(key);        } catch (Exception e) {            log.error("get key:{} error", key, e);            return null;        } finally {            close(jedis);        }    }    /**     * 删除key     *     * @param key     * @return     */    public Long del(String key) {        Jedis jedis = null;        try {            jedis = getJedis();            return jedis.del(key.getBytes());        } catch (Exception e) {            log.error("del key:{} error", key, e);            return null;        } finally {            close(jedis);        }    }    /**     * 判断key是否存在     *     * @param key     * @return     */    public Boolean exists(String key) {        Jedis jedis = null;        try {            jedis = getJedis();            return jedis.exists(key.getBytes());        } catch (Exception e) {            log.error("exists key:{} error", key, e);            return null;        } finally {            close(jedis);        }    }    /**     * 设值key过期时间     *     * @param key     * @param expireTime 过期时间, 单位: s     * @return     */    public Long expire(String key, int expireTime) {        Jedis jedis = null;        try {            jedis = getJedis();            return jedis.expire(key.getBytes(), expireTime);        } catch (Exception e) {            log.error("expire key:{} error", key, e);            return null;        } finally {            close(jedis);        }    }    /**     * 获取剩余时间     *     * @param key     * @return     */    public Long ttl(String key) {        Jedis jedis = null;        try {            jedis = getJedis();            return jedis.ttl(key);        } catch (Exception e) {            log.error("ttl key:{} error", key, e);            return null;        } finally {            close(jedis);        }    }    private void close(Jedis jedis) {        if (null != jedis) {            jedis.close();        }    }}

3.自定义注解@ApiIdempotent

package com.wangzaiplus.test.annotation;
import java.lang.annotation.ElementType;import java.lang.annotation.Retention;import java.lang.annotation.RetentionPolicy;import java.lang.annotation.Target;
/** * 在需要保证 接口幂等性 的Controller的方法上使用此注解 */@Target({ElementType.METHOD})@Retention(RetentionPolicy.RUNTIME)public @interface ApiIdempotent {}

4.ApiIdempotentInterceptor拦截器

package com.wangzaiplus.test.interceptor;
import com.wangzaiplus.test.annotation.ApiIdempotent;import com.wangzaiplus.test.service.TokenService;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.web.method.HandlerMethod;import org.springframework.web.servlet.HandlerInterceptor;import org.springframework.web.servlet.ModelAndView;
import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import java.lang.reflect.Method;
/** * 接口幂等性拦截器 */public class ApiIdempotentInterceptor implements HandlerInterceptor {
    @Autowired    private TokenService tokenService;
    @Override    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) {        if (!(handler instanceof HandlerMethod)) {            return true;        }
        HandlerMethod handlerMethod = (HandlerMethod) handler;        Method method = handlerMethod.getMethod();
        ApiIdempotent methodAnnotation = method.getAnnotation(ApiIdempotent.class);        if (methodAnnotation != null) {            check(request);// 幂等性校验, 校验通过则放行, 校验失败则抛出异常, 并通过统一异常处理返回友好提示        }
        return true;    }
    private void check(HttpServletRequest request) {        tokenService.checkToken(request);    }
    @Override    public void postHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, ModelAndView modelAndView) throws Exception {    }
    @Override    public void afterCompletion(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, Exception e) throws Exception {    }}

5.TokenServiceImpl

package com.wangzaiplus.test.service.impl;
import com.wangzaiplus.test.common.Constant;import com.wangzaiplus.test.common.ResponseCode;import com.wangzaiplus.test.common.ServerResponse;import com.wangzaiplus.test.exception.ServiceException;import com.wangzaiplus.test.service.TokenService;import com.wangzaiplus.test.util.JedisUtil;import com.wangzaiplus.test.util.RandomUtil;import lombok.extern.slf4j.Slf4j;import org.apache.commons.lang3.StringUtils;import org.apache.commons.lang3.text.StrBuilder;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.stereotype.Service;
import javax.servlet.http.HttpServletRequest;
@Servicepublic class TokenServiceImpl implements TokenService {
    private static final String TOKEN_NAME = "token";
    @Autowired    private JedisUtil jedisUtil;
    @Override    public ServerResponse createToken() {        String str = RandomUtil.UUID32();        StrBuilder token = new StrBuilder();        token.append(Constant.Redis.TOKEN_PREFIX).append(str);
        jedisUtil.set(token.toString(), token.toString(), Constant.Redis.EXPIRE_TIME_MINUTE);
        return ServerResponse.success(token.toString());    }
    @Override    public void checkToken(HttpServletRequest request) {        String token = request.getHeader(TOKEN_NAME);        if (StringUtils.isBlank(token)) {// header中不存在token            token = request.getParameter(TOKEN_NAME);            if (StringUtils.isBlank(token)) {// parameter中也不存在token                throw new ServiceException(ResponseCode.ILLEGAL_ARGUMENT.getMsg());            }        }
        if (!jedisUtil.exists(token)) {            throw new ServiceException(ResponseCode.REPETITIVE_OPERATION.getMsg());        }
        Long del = jedisUtil.del(token);        if (del <= 0) {            throw new ServiceException(ResponseCode.REPETITIVE_OPERATION.getMsg());        }    }
}

6.TestApplication

package com.wangzaiplus.test;
import com.wangzaiplus.test.interceptor.ApiIdempotentInterceptor;import org.mybatis.spring.annotation.MapperScan;import org.springframework.boot.SpringApplication;import org.springframework.boot.autoconfigure.SpringBootApplication;import org.springframework.context.annotation.Bean;import org.springframework.web.cors.CorsConfiguration;import org.springframework.web.cors.UrlBasedCorsConfigurationSource;import org.springframework.web.filter.CorsFilter;import org.springframework.web.servlet.config.annotation.InterceptorRegistry;import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;
@SpringBootApplication@MapperScan("com.wangzaiplus.test.mapper")public class TestApplication  extends WebMvcConfigurerAdapter {
    public static void main(String[] args) {        SpringApplication.run(TestApplication.class, args);    }
    /**     * 跨域     * @return     */    @Bean    public CorsFilter corsFilter() {        final UrlBasedCorsConfigurationSource urlBasedCorsConfigurationSource = new UrlBasedCorsConfigurationSource();        final CorsConfiguration corsConfiguration = new CorsConfiguration();        corsConfiguration.setAllowCredentials(true);        corsConfiguration.addAllowedOrigin("*");        corsConfiguration.addAllowedHeader("*");        corsConfiguration.addAllowedMethod("*");        urlBasedCorsConfigurationSource.registerCorsConfiguration("/**", corsConfiguration);        return new CorsFilter(urlBasedCorsConfigurationSource);    }
    @Override    public void addInterceptors(InterceptorRegistry registry) {        // 接口幂等性拦截器        registry.addInterceptor(apiIdempotentInterceptor());        super.addInterceptors(registry);    }
    @Bean    public ApiIdempotentInterceptor apiIdempotentInterceptor() {        return new ApiIdempotentInterceptor();    }
}

OK, 目前为止, 校验代码准备就绪, 接下来测试验证。

七、测试验证

1.获取token的控制器TokenController

package com.wangzaiplus.test.controller;
import com.wangzaiplus.test.common.ServerResponse;import com.wangzaiplus.test.service.TokenService;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.web.bind.annotation.GetMapping;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.RestController;
@RestController@RequestMapping("/token")public class TokenController {
    @Autowired    private TokenService tokenService;
    @GetMapping    public ServerResponse token() {        return tokenService.createToken();    }
}

2.TestController, 注意@ApiIdempotent注解, 在需要幂等性校验的方法上声明此注解即可, 不需要校验的无影响

package com.wangzaiplus.test.controller;
import com.wangzaiplus.test.annotation.ApiIdempotent;import com.wangzaiplus.test.common.ServerResponse;import com.wangzaiplus.test.service.TestService;import lombok.extern.slf4j.Slf4j;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.web.bind.annotation.PostMapping;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.RestController;
@RestController@RequestMapping("/test")@Slf4jpublic class TestController {
    @Autowired    private TestService testService;
    @ApiIdempotent    @PostMapping("testIdempotence")    public ServerResponse testIdempotence() {        return testService.testIdempotence();    }}

3.获取token

查看redis

4.测试接口安全性: 利用jmeter测试工具模拟50个并发请求, 将上一步获取到的token作为参数

5.header或参数均不传token, 或者token值为空, 或者token值乱填, 均无法通过校验, 如token值为"abcd"

八、注意点(非常重要)

上图中, 不能单纯的直接删除token而不校验是否删除成功, 会出现并发安全性问题, 因为, 有可能多个线程同时走到第46行, 此时token还未被删除, 所以继续往下执行, 如果不校验jedisUtil.del(token)的删除结果而直接放行, 那么还是会出现重复提交问题, 即使实际上只有一次真正的删除操作, 下面重现一下

稍微修改一下代码: