Springboot + redis + 注解 + 拦截器来实现接口幂等性校验

1. SpringBoot 整合篇

2. 手写一套迷你版HTTP服务器

3. 记住：永远不要在MySQL中使用UTF-8

4. Springboot启动原理解析

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

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>

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

@Slf4j

public 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();

        }

    }

}

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 {

}

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 {

    }

}

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;

@Service

public 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());

        }

    }

}

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")

@Slf4j

public class TestController {

    @Autowired

    private TestService testService;

    @ApiIdempotent

    @PostMapping("testIdempotence")

    public ServerResponse testIdempotence() {

        return testService.testIdempotence();

    }

}

3、获取token