服务器端防止Form表单重复提交

最新推荐文章于 2023-06-30 16:16:38 发布

原创最新推荐文章于 2023-06-30 16:16:38 发布 · 1.2k 阅读

0 ·

CC 4.0 BY-SA版权

杂集各种资料收集专栏收录该内容

15 篇文章

订阅专栏

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>