springboot配合redis自定义注解和拦截器实现接口的幂等性

一、幂等性介绍

什么是幂等

幂等性简单来说就是用户对同一个操作发起多次请求以后，对于数据的影响的结果是不变的，一次请求跟N次请求的结果是一样的

幂等场景

支付场景：如果用户对同一个订单发起两次支付操作，那么这个时候服务端不去做相应的处理的话，它就会完成两笔扣款记录，那么这个地方就会造成用户的资金损失，这种情况是绝对不允许在互联网产品上出现的。

幂等的实现方法

1）唯一索引 – 防止新增脏数据

2）token机制 – 防止页面重复提交

3）悲观锁 – 获取数据的时候加锁(锁表或锁行)

4）乐观锁 – 基于版本号version实现, 在更新数据那一刻校验数据

5）分布式锁 – redis(jedis、redisson)或zookeeper实现

6）状态机 – 状态变更, 更新数据时判断状态

今天要讲的是第二种–token机制，token机制的实现方法也有很多种，今天要说的是token机制的实现方法是使用springboot搭配redis利用自定义注解和拦截器实现的，流程如下

二、代码实现

1.公共类

package com.springbootidempotence.common;

import com.fasterxml.jackson.annotation.JsonIgnore;

import java.io.Serializable;

public class ServerResponse implements Serializable{

    private static final long serialVersionUID = 7498483649536881777L;

    private Integer status;

    private String msg;

    private Object data;

    public ServerResponse() {
    }

    public ServerResponse(Integer status, String msg, Object data) {
        this.status = status;
        this.msg = msg;
        this.data = data;
    }

    @JsonIgnore
    public boolean isSuccess() {
        return this.status == ResponseCode.SUCCESS.getCode();
    }

    public static ServerResponse success() {
        return new ServerResponse(ResponseCode.SUCCESS.getCode(), null, null);
    }

    public static ServerResponse success(String msg) {
        return new ServerResponse(ResponseCode.SUCCESS.getCode(), msg, null);
    }

    public static ServerResponse success(Object data) {
        return new ServerResponse(ResponseCode.SUCCESS.getCode(), null, data);
    }

    public static ServerResponse success(String msg, Object data) {
        return new ServerResponse(ResponseCode.SUCCESS.getCode(), msg, data);
    }

    public static ServerResponse error(String msg) {
        return new ServerResponse(ResponseCode.ERROR.getCode(), msg, null);
    }

    public static ServerResponse error(Object data) {
        return new ServerResponse(ResponseCode.ERROR.getCode(), null, data);
    }

    public static ServerResponse error(String msg, Object data) {
        return new ServerResponse(ResponseCode.ERROR.getCode(), msg, data);
    }

    public Integer getStatus() {
        return status;
    }

    public void setStatus(Integer status) {
        this.status = status;
    }

    public String getMsg() {
        return msg;
    }

    public void setMsg(String msg) {
        this.msg = msg;
    }

    public Object getData() {
        return data;
    }

    public void setData(Object data) {
        this.data = data;
    }
}

package com.springbootidempotence.common;

public enum ResponseCode {

    // 系统模块
    SUCCESS(0, "操作成功"),
    ERROR(1, "操作失败"),
    SERVER_ERROR(500, "服务器异常"),

    // 通用模块 1xxxx
    ILLEGAL_ARGUMENT(10000, "参数不合法"),
    REPETITIVE_OPERATION(10001, "请勿重复操作");

    ResponseCode(Integer code, String msg) {
        this.code = code;
        this.msg = msg;
    }

    private Integer code;

    private String msg;

    public Integer getCode() {
        return code;
    }

    public void setCode(Integer code) {
        this.code = code;
    }

    public String getMsg() {
        return msg;
    }

    public void setMsg(String msg) {
        this.msg = msg;
    }
}

2.工具类

@Configuration
public class JedisConfig {

    @Bean(name = "jedisPoolConfig")
    public JedisPoolConfig jedisPoolConfig(){
        JedisPoolConfig jedisPoolConfig = new JedisPoolConfig();
        jedisPoolConfig.setMaxTotal(500);
        jedisPoolConfig.setMaxIdle(200);
        jedisPoolConfig.setNumTestsPerEvictionRun(1024);
        jedisPoolConfig.setTimeBetweenEvictionRunsMillis(30000);
        jedisPoolConfig.setMinEvictableIdleTimeMillis(-1);
        jedisPoolConfig.setSoftMinEvictableIdleTimeMillis(10000);
        jedisPoolConfig.setMaxWaitMillis(1500);
        jedisPoolConfig.setTestOnBorrow(true);
        jedisPoolConfig.setTestWhileIdle(true);
        jedisPoolConfig.setTestOnReturn(false);
        jedisPoolConfig.setJmxEnabled(true);
        jedisPoolConfig.setBlockWhenExhausted(false);
        return jedisPoolConfig;
    }

    @Bean
    public JedisPool redisPool() {
        String host = "127.0.0.1";
        int port = 6379;
        return new JedisPool(jedisPoolConfig(), host, port);
    }

}

package com.springbootidempotence.utils;
 
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();
        }
    }
 
}

3.实现自定义注解

/**
 * ElementType.METHOD：该注解作用于方法上
 * RetentionPolicy.RUNTIME：表示它在运行时
 */
@Target({ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
public @interface ApiIdempotent {

}

4.定义生成token的service

public interface TokenService {

    ServerResponse createToken();

    void checkToken(HttpServletRequest request);
    
    ServerResponse testIdempotence();
}

@Service
public class TokenServiceImpl implements TokenService {
 
    private static final String TOKEN_NAME = "token";

    private static final String TOKEN_PREFIX = "token:";

    // 过期时间, 60s, 一分钟
    private static final Integer EXPIRE_TIME_MINUTE = 60 * 5;
 
    @Autowired
    private JedisUtil jedisUtil;
 
    @Override
    public ServerResponse createToken() {
        String str = UUID.randomUUID().toString().replaceAll("-", "");
        StringBuilder token = new StringBuilder();
        token.append(TOKEN_PREFIX).append(str);
 
        jedisUtil.set(token.toString(), token.toString(), 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());
        }
    }
    
    @Override
    public ServerResponse testIdempotence() {
        return ServerResponse.success("testIdempotence: success");
    }
 
}

5.自定义异常类

/**
 * 业务逻辑异常
 */
public class ServiceException extends RuntimeException{

    private String code;
    private String msg;

    public ServiceException() {
    }

    public ServiceException(String msg) {
        this.msg = msg;
    }

    public ServiceException(String code, String msg) {
        this.code = code;
        this.msg = msg;
    }

    public String getCode() {
        return code;
    }

    public void setCode(String code) {
        this.code = code;
    }

    public String getMsg() {
        return msg;
    }

    public void setMsg(String msg) {
        this.msg = msg;
    }
}

6.自定义拦截器

package com.springbootidempotence.interceptor;
 

import com.springbootidempotence.annotation.ApiIdempotent;
import com.springbootidempotence.service.TokenService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
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
 */
@Component
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 {
    }
}

7.注册拦截器

package com.springbootidempotence.config;

import com.springbootidempotence.interceptor.ApiIdempotentInterceptor;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
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.WebMvcConfigurer;

/**
 * Web配置文件
 */
@Configuration
public class WebMvcConfig implements WebMvcConfigurer {

    /**
     * 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);
    }

    //关键，将拦截器作为bean写入配置中
    @Bean
    public ApiIdempotentInterceptor apiIdempotentInterceptor(){
        return new ApiIdempotentInterceptor();
    }

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

8.controller层

哪个接口需要实现幂等性就加入自定义注解@ApiIdempotent

@RestController
@RequestMapping("/token")
public class TokenController {
 
    @Autowired
    private TokenService tokenService;
    
    @GetMapping("/create")
    public ServerResponse token() {
        return tokenService.createToken();
    }

    @ApiIdempotent
    @PostMapping("/testIdempotence")
    public ServerResponse testIdempotence() {
        return tokenService.testIdempotence();
    }
}

三、测试

首先生成token

然后拿生成的token去另外一个接口去测试幂等性

这里要注意：请求头的名字是token，它的值是token:c8c5ef3256294bafbcdecd592259cd6f，这里要和redis中存储的值要一样。

--end--