服务器端防止Form表单重复提交

来源：互联网发布：通信网络性能指标编辑：程序博客网时间：2024/06/05 08:10

工程目录结构：

主要代码：

令牌类：

package com.mth.token;import java.security.MessageDigest;import java.security.NoSuchAlgorithmException;import java.util.Random;import sun.misc.BASE64Encoder;/** *  * @ClassName: Token 单例 * @Description: 产生一个令牌 MessageDigest BASE64Encoder * @author mth 75100313@qq.com * @date 2014-3-20 上午08:15:33 *  */public class Token {    private static final Token tokenInstance = new Token();    private Token() {super();// TODO Auto-generated constructor stub    }        public static Token getInstance(){return tokenInstance;    }    public String getToken() {//生成随机值String token = System.currentTimeMillis() + new Random().nextInt() + "";MessageDigest md;try {    //得到数据摘要    md = MessageDigest.getInstance("md5");    byte[] md5 = md.digest(token.getBytes());    //编码    BASE64Encoder encoder = new BASE64Encoder();    String str = encoder.encode(md5);        return str;} catch (NoSuchAlgorithmException e) {    new RuntimeException(e);}return null;    }}

表单servlet(跳转到form.jsp)

package com.mth.form;import java.io.IOException;import java.security.MessageDigest;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import com.mth.token.Token;/** *  * @ClassName: FormServlet * @Description: 通过这个servlet来把令牌发送到前台的隐藏域 * @author mth 75100313@qq.com * @date 2014-3-20 上午09:03:56 *  */public class FormServlet extends HttpServlet {    public void doGet(HttpServletRequest request, HttpServletResponse response)    throws ServletException, IOException {//获得一个编码Token token = Token.getInstance();String str = token.getToken();request.getSession().setAttribute("token", str);request.getRequestDispatcher("/form.jsp").forward(request, response);    }    public void doPost(HttpServletRequest request, HttpServletResponse response)    throws ServletException, IOException {doGet(request, response);    }}

处理重复提交（打印一句话没连数据库）

package com.mth.form;import java.io.IOException;import java.io.PrintWriter;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;/** *  * @ClassName: CheckForm * @Description: 处理表单重复提交 * @author mth 75100313@qq.com * @date 2014-3-20 上午08:39:47 *  */public class CheckForm extends HttpServlet {    public void doGet(HttpServletRequest request, HttpServletResponse response)    throws ServletException, IOException {boolean b = check(request);if (b) {    request.getSession().removeAttribute("token");    System.out.println("注册成功过！");} else {    System.out.println("请不要重复登陆！");}    }    /**     *      * @Title: check     * @Description:检查表单是否有效     * @param @param request     * @param @return 设定文件     * @return boolean 返回类型     * @throws     */    private boolean check(HttpServletRequest request) {//获得隐藏域的值String hidden = request.getParameter("hidden");String token = (String) request.getSession().getAttribute("token");//直接登陆情况直接到form.jsp页面登陆此时hidden值为""if (hidden == null || "".equals(hidden)) {    System.out.println("不能直接登陆");    return false;}//服务器端没有这个令牌if (token == null) {    System.out.println("服务器端没有了 已经提交过");    return false;}//服务器和隐藏域的值不等if (!hidden.equals(token)) {    System.out.println("不相等 ，不能登陆");    return false;}return true;    }    public void doPost(HttpServletRequest request, HttpServletResponse response)    throws ServletException, IOException {doGet(request, response);    }}

form.jsp页面：

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%><%    String path = request.getContextPath();    String basePath = request.getScheme() + "://"    + request.getServerName() + ":" + request.getServerPort()    + path + "/";%><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html><head><base href="<%=basePath%>"><title>服务器端防止表单重复提交</title></head><body><form action="/FromSubmitMore/CheckForm" method="post"><input type="hidden" name="hidden" value="${token }">用户名:<input type="text"><br /><input type="submit" value="login"></form></body></html>

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