冪等註解實現

業務需求：

有些前端，或者第三方的接口請求要實現冪等操作，考慮到節省開發時間，做了一個可配置的冪等註解

先說明基本的實現原理和優缺點，後面直接貼代碼：

 

原理：

1.通過自定義註解配置冪等參數：唯一主鍵，過期時間；

2.通過HandleInterceptor攔截請求方法和註解參數，進行校驗

3.根據唯一主鍵，主鍵的值，過期時間，請求url來生成唯一token存redis。後續重複請求判斷redis是否已經存在key。如果redis存在則說明已經執行過了（不管執行失敗還是成功都算）

優點：

只要在方法上添加註解配置

@AutoIdempotent(pkId = "orderDetailsId",expire=300)

則接口就實現過期時間內的冪等，減少業務開發時間

缺點：

需藉助redis，只是過期時間內的冪等，過期時間外的就不支持了

核心代碼：

註解：

@Target({ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
public @interface AutoIdempotent {
    //冪等控制主鍵
    String pkId();

    //鍵過期時間單位：s
    long expire() default 120;
}

冪等攔截器：

package com.ddmc.interceptor.autoidempotent;

import com.ddmc.exception.enums.CommonAssertEnum;
import com.ddmc.interceptor.autoidempotent.annotation.AutoIdempotent;
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;

/**
 * 冪等攔截器
 *
 * @author yuJie
 * @since 2020/5/16
 */
@Component
public class AutoIdempotentInterceptor implements HandlerInterceptor {

    @Autowired
    private TokenService tokenService;

    /**
     * 預處理
     *
     * @param request
     * @param response
     * @param handler
     * @return
     * @throws Exception
     */
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {

        if (!(handler instanceof HandlerMethod)) {
            return true;
        }
        HandlerMethod handlerMethod = (HandlerMethod) handler;
        Method method = handlerMethod.getMethod();
        AutoIdempotent methodAnnotation = method.getAnnotation(AutoIdempotent.class);
        if (methodAnnotation != null) {
            try {
                /**
                 * 冪等性校驗, 校驗通過則放行, 校驗失敗則拋出異常, 並通過統一異常處理返回
                 */
                String pkId = methodAnnotation.pkId();
                long expire = methodAnnotation.expire();
                return tokenService.checkToken(request, pkId,expire);
            } catch (Exception ex) {
                CommonAssertEnum.DO_NOT_SUBMIT_AGAIN.assertFail();
            }
        }
        //必須返回true,否則會被攔截一切請求
        return true;
    }


    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {

    }

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {

    }

}

Token操作類：

 

package com.ddmc.interceptor.autoidempotent;

import com.ddmc.exception.enums.CommonAssertEnum;
import com.ddmc.utils.http.RequestHandleUtil;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.stereotype.Service;

import javax.servlet.http.HttpServletRequest;
import java.util.concurrent.TimeUnit;

/**
 * token操作實現類
 *
 * @author yuJie
 * @since 2020/5/16
 */
@Service
public class TokenServiceImpl implements TokenService {
    /**
     * 冪等檢測key過期時間默認120s
     */
    private final static long expire = 120;
    private final static String AUTO_IDEMPOTENT_KEY = "md";
    @Autowired
    private RedisTemplate<String, Object> solarRedisTemplate;

    /**
     * 創建token
     *
     * @return
     */
    @Override
    public Boolean saveToken(String key, String token) {
        solarRedisTemplate.opsForValue().setIfAbsent(key, token, expire, TimeUnit.SECONDS);
        return Boolean.TRUE;
    }


    /**
     * 檢驗token
     *
     * @param request
     * @return
     */
    @Override
    public boolean checkToken(HttpServletRequest request, String pkId,long expire) throws Exception {
        String version = request.getHeader("version");
        String pkIdValue = RequestHandleUtil.getReqParam(request, pkId);
        String requestURI = request.getRequestURI();
        //控制redis key的長度
        requestURI = requestURI.substring(requestURI.length() - 20);
        StringBuffer key = new StringBuffer();
        key.append(AUTO_IDEMPOTENT_KEY)
                .append(requestURI).append(":")
                .append(pkId == null ? "id" : pkId).append(":")
                .append(pkIdValue == null ? "value" : pkIdValue).append(":")
                .append(version == null ? "0" : version);
        if (solarRedisTemplate.hasKey(key.toString())) {
            CommonAssertEnum.DO_NOT_SUBMIT_AGAIN.assertFail();
        } else {
            solarRedisTemplate.opsForValue().setIfAbsent(key.toString(), "exist", expire, TimeUnit.SECONDS);
        }
        return true;
    }
}

冪等攔截器配置：

package com.ddmc.interceptor.autoidempotent;

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

import javax.annotation.Resource;

/**
 * 冪等攔截器配置
 *
 * @author yuJie
 * @since 2020/5/16
 */
@Configuration
public class WebAutoIdempotentConfiguration extends WebMvcConfigurationSupport {

    @Resource
    private AutoIdempotentInterceptor autoIdempotentInterceptor;

    /**
     * 添加攔截器
     *
     * @param registry
     */
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(autoIdempotentInterceptor);
        super.addInterceptors(registry);
    }
}

因爲需要從post的body獲取傳遞的參數，而body的流數據只能拿到一次，所以需要額外的filter包裝器：

package com.ddmc.filter;

import com.ddmc.utils.http.BodyReaderHttpServletRequestWrapper;
import org.springframework.core.annotation.Order;
import org.springframework.stereotype.Component;

import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
import java.io.IOException;

/**
 * 類作用描述
 *
 * @author yuJie
 * @since 2020/5/18
 */
@Order(0)
@WebFilter(filterName = "httpServletRequestWrapperFilter", urlPatterns = {"/*"})
@Component
public class HttpServletRequestWrapperFilter implements Filter {

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {

    }

    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
            throws IOException, ServletException {

        ServletRequest requestWrapper = null;

        if (request instanceof HttpServletRequest) {
            HttpServletRequest httpRequest = (HttpServletRequest) request;
            //遇到post方法纔對request進行包裝
            String methodType = httpRequest.getMethod();
            if ("POST".equals(methodType)) {
                requestWrapper = new BodyReaderHttpServletRequestWrapper(
                        (HttpServletRequest) request);
            }
        }
        if (null == requestWrapper) {
            chain.doFilter(request, response);
        } else {
            chain.doFilter(requestWrapper, response);
        }
    }

    @Override
    public void destroy() {

    }
}

增加下壓測和redis內存佔用情況：

50000次請求，redis內存佔用