JAVA–利用Filter和session防止页面重复提交

时间：2025-04-03 18:37:55

JAVA–利用Filter和session防止页面重复提交
解决思路:
1 用户访问表单页面,先经过过滤器,过滤器设置一个随机id作为token令牌, 并将该token放入表单隐藏域中.
2 表单响应到浏览器,用户填充数据后提交请求;
3 请求经过过滤器,过滤器获取表单中的令牌进行验证,如果和之前生成的令牌一致,则将请求放行,并且清空令牌;
4 如果用户重复提交表单,请求经过过滤器,过滤器进行验证.因为第一次放行后令牌已经清空失效,令牌不一致,不放行.跳转到提醒界面.

需用知识:
1 过滤器基础知识
2 servlet基础知识
3 filter基础知识
4 jsp基础知识

代码实现

1 jsp实现form表单页面

<%@ page language="java" contentType="text/html; charset=UTF-8"

    pageEncoding="UTF-8"%>

<!DOCTYPE html>

<html>

<head>

<meta charset="UTF-8">

<title>Insert title here</title>

</head>

<body>

	<form action="login" method="post">

		<!-- 利用表单的隐藏域 保存token令牌 -->

		<!--  ${token}等价于req.getsession().getAttribute("token")-->

		<input type="hidden" name="token" value="${token}" />

		用户名:<input type="text" name="username"/><br/>

		密码:<input type="password" name="password"/><br/>

		<input type="submit" value="login"/>

	</form>

</body>

</html>

　　

2 filter过滤器

package com.woniu.filter.controler;

import java.io.IOException;

import java.util.UUID;

import javax.servlet.Filter;

import javax.servlet.FilterChain;

import javax.servlet.FilterConfig;

import javax.servlet.ServletException;

import javax.servlet.ServletRequest;

import javax.servlet.ServletResponse;

import javax.servlet.annotation.WebFilter;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

/**

 * Servlet Filter implementation class TokenFilte

 */

//过滤所有servlet

@WebFilter("*")

public class TokenFilte implements Filter {

    public TokenFilte() {

        // TODO Auto-generated constructor stub

    }

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

		// TODO Auto-generated method stub

		//设置编码集

		request.setCharacterEncoding("utf-8");

		response.setCharacterEncoding("utf-8");

		response.setContentType("text/html;charser=utr-8");

		//向下转型

		HttpServletRequest req=(HttpServletRequest) request;

		HttpServletResponse resp=(HttpServletResponse) response;

		//获取表单的token

		String parameterToken = req.getParameter("token");

		//获取session中的token

		String sessionToken = (String) req.getSession().getAttribute("token");

		//判断表单的token,不为空说明用户已经提交form表单,需要验证是否重复提交,

		//为空说明是第一次进入登录页面,需要设置token

		if (parameterToken!=null) {

			//判断两个令牌是否相等,相等则放行,并重置令牌

			if(parameterToken.equals(sessionToken)) {

				//重置令牌

				req.getSession().removeAttribute("token");

				chain.doFilter(request, response);

			}else {//说明是重复提交,转发到提示页面

				req.getRequestDispatcher("repeatReminder").forward(request, response);

			}

		}else {//第一次进来,需要设置令牌

			//生成宇宙唯一码

			String token = UUID.randomUUID().toString();

			//设置session

			req.getSession().setAttribute("token",token);

			//放行

			chain.doFilter(request, response);

		}

	}

	@Override

	public void destroy() {

		// TODO Auto-generated method stub

	}

	@Override

	public void init(FilterConfig filterConfig) throws ServletException {

		// TODO Auto-generated method stub

	}

}

　　

3 表单响应的servlet
利用线程睡30秒,模拟网络拥堵

package com.woniu.filter.controler;

import java.io.IOException;

import javax.servlet.ServletException;

import javax.servlet.annotation.WebServlet;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

/**

 * Servlet implementation class PrintUser

 */

@WebServlet("/login")

public class Login extends HttpServlet {

	private static final long serialVersionUID = 1L;

    public Login() {

        super();

        // TODO Auto-generated constructor stub

    }

	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

		try {

			//线程睡30秒,便于演示网络拥堵

			Thread.sleep(30000);

			response.getWriter().write("登录成功");

		} catch (InterruptedException e) {

			// TODO Auto-generated catch block

			e.printStackTrace();

		}

	}

	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

		doGet(request, response);

	}

}

　　

4 重复提交时响应的servlet
重复提交时跳转到该提醒页面

package com.woniu.filter.controler;

import java.io.IOException;

import javax.servlet.ServletException;

import javax.servlet.annotation.WebServlet;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

/**

 * Servlet implementation class repeatReminder

 */

@WebServlet("/repeatReminder")

public class repeatReminder extends HttpServlet {

	private static final long serialVersionUID = 1L;

    public repeatReminder() {

        super();

        // TODO Auto-generated constructor stub

    }

	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

		response.getWriter().write("页面正在处理,请勿重复提交");

	}

	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

		// TODO Auto-generated method stub

		doGet(request, response);

	}

}

　　

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