JAVA 重复提交

FormServlet

package servlet;

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;

import util.TokenProcessor;

/**

 * Servlet implementation class FormServlet

 */

public class FormServlet extends HttpServlet {

    private static final long serialVersionUID = 1L;

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

        doPost(request, response);

    }

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

        String token = TokenProcessor.getInstance().makeToken();

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

        request.getRequestDispatcher("/form.jsp").forward(request, response);

    }

}

form.jsp

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">

<html>

<head>

<title>form表单</title>

</head>

<body>

    <form action="${pageContext.request.contextPath}/DoFormServlet"

        method="post">

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

            type="text" name="username"><input type="submit" value="提交">

    </form>

</body>

</html>

提交DoFormServlet

package servlet;

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;

public class DoFormServlet extends HttpServlet {

    private static final long serialVersionUID = 1L;

    public DoFormServlet() {

        super();

    }

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

        this.doGet(request, response);

    }

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

        boolean b = isRepeatSubmit(request);

        if(b){

            System.out.println("请不要重复提交");

            return;

        }

         request.getSession().removeAttribute("token");//移除session中的token

        System.out.println("处理用户提交请求！！");

    }

    private boolean isRepeatSubmit(HttpServletRequest request){

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

        if(client_token == null){

            return true;

        }

        String server_token = (String) request.getSession().getAttribute("token");

        if(server_token == null){

            return true;

        }

        if(!client_token.equals(server_token)){

            return true;

        }

        return false;

    }

}

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