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本文介绍如何使用token来防止前端重复提交的问题。

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目录

• 1.思路
• 2.拦截器源码实现
• 3.注解源码
• 4.拦截器的配置
• 5.使用指南
• 6.结语

思路

1.添加拦截器，拦截需要防重复提交的请求
2.通过注解@Token来添加token/移除token    
3.前端页面表单添加（如果是Ajax请求则需要在请求的json数据中添加token值）

核心源码

拦截器源码实现

/**
 * com.xxx.interceptor.TokenInterceptor.java
 * Copyright 2018 Lifangyu, Inc. All rights reserved.
 */
package com.xxx.common.interceptor;

import org.apache.log4j.Logger;
import org.springframework.web.method.HandlerMethod;
import org.springframework.web.servlet.handler.HandlerInterceptorAdapter;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.lang.reflect.Method;
import java.util.Random;
import java.util.UUID;

/**
 * Desc:防重复提交的拦截器
 * <p>
 * Created by lifangyu on 2018/02/27.
 */
public class TokenInterceptor extends HandlerInterceptorAdapter {

    Logger logger = Logger.getLogger(TokenInterceptor.class);

    static String splitFlag = "_";

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        if (handler instanceof HandlerMethod) {
            HandlerMethod handlerMethod = (HandlerMethod) handler;
            Method method = handlerMethod.getMethod();
            Token annotation = method.getAnnotation(Token.class);
            if (annotation == null) {
                return true;
            }
            
            boolean needSaveSession = annotation.add();
            if (needSaveSession) {
                Random random = new Random();
                String uuid = UUID.randomUUID().toString().replace(splitFlag, String.valueOf(random.nextInt(100000)));
                String tokenValue = String.valueOf(System.currentTimeMillis());
                request.setAttribute("token", uuid + splitFlag + tokenValue);
                // session 中 token 的key 每次都是变化的[适应浏览器 打开多个带有token的页面不会有覆盖session的key]
                request.getSession(true).setAttribute(uuid, tokenValue);
            }
            boolean needRemoveSession = annotation.remove();
            if (needRemoveSession) {
                if (isRepeatSubmit(request)) {
                    logger.warn("please don't repeat submit,url:" + request.getServletPath());
                    return false;
                }
                String clinetToken = request.getParameter("token");
                if (clinetToken != null && clinetToken.indexOf(splitFlag) > -1) {
                    request.getSession(true).removeAttribute(clinetToken.split("_")[0]);
                }
            }
            return true;
        } else {
            return super.preHandle(request, response, handler);
        }
    }

    /**
     * 判断是否是重复提交
     *
     * @param request
     * @return
     */
    private boolean isRepeatSubmit(HttpServletRequest request) {

        String clinetToken = request.getParameter("token");

        if (clinetToken == null) {
            return true;
        }
        String uuid = clinetToken.split("_")[0];
        String token = clinetToken.split("_")[1];
        String serverToken = (String) request.getSession(true).getAttribute(uuid);
        if (serverToken == null) {
            return true;
        }
        if (!serverToken.equals(token)) {
            return true;
        }

        return false;
    }
}

注解源码

/**
 * com.xxx.interceptor.Token.java
 * Copyright 2018 Lifangyu, Inc. All rights reserved.
 */
package com.xxx.common.interceptor;

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

/**
 * Desc:Token 注解
 * <p>
 * Created by lifangyu on 2018/02/27.
 */
@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
public @interface Token {

    /**
     * 添加token的开关[true：添加；false:不添加，default：false]
     *
     * @return
     */
    boolean add() default false;

    /**
     * 移除token的开关[true：删除；false:不删除，default：false]
     *
     * @return
     */
    boolean remove() default false;

}

拦截器的配置

在springMVC的servlet配置文件中配置拦截器

<!-- 拦截器配置 -->
<mvc:interceptors>
	<!-- 配置Token拦截器，防止用户重复提交数据 -->
	<mvc:interceptor>
		<mvc:mapping path="/**"/>
		<bean class="com.xxx.interceptor.TokenInterceptor"/>
	</mvc:interceptor>
</mvc:interceptors>

使用指南

1.在进入页面的controller方法上添加注解@Token(add=true)

@Token(add = true)
@RequestMapping("toXxxHtml")
public String toXxxHtml(Model mv) {
   ......
   return "xxx/xxxHtml";
}

2.在页面toXxxHtml.html添加

<form id="xxx_submit_form" class="form-horizontal" action="${ctx}/xxx/addXxx.do" method="post">
   ......
   <!-- 注：name必须是token -->
   <input type="hidden"  name="token" value="${token!''}"/>
   ......
</form>

3.在防止重复提交的controller方法上添加@Token(remove = true)

@Token(remove = true)
@RequestMapping("addXxx")
public String addXxx() throws Exception {
   ......
   return "redirect:toXxxHtml.do";
}

结语

到此本文就结束了，欢迎大家继续关注更多Spring案例。

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