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session 的应用——防止表单重复提交——2.0版

2013-09-10 19:49 344 查看

session 的应用——防止表单重复提交——2.0版(使用了Struts1 中的重复提交组件: TokenProcessor和自定义标签)

Html代码

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

    pageEncoding="UTF-8"%>



<%@ taglib prefix="syh" uri="http://java.syh.com/jsp/syh/core"%>

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">

<html>

<head>

<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">

<title>Insert title here</title>



<script type="text/javascript">



    //点击 "提交" 按钮, 只能点击一次

    var flag = true;





    function token(btn){

        if(flag){

            flag = false;

            return true;

        }else{

            alert('已经提交过了');

        }

    }



    /*

    下面的JS代码对 IE 不使用，对于 FF

    function token2(btn){

        if(flag){

            btn.disabled = true;

            return true;

        }

    }

    */



</script>

</head>

<body>



        



    <form action="LoginServlet" method="post" id="regForm">

        

        <syh:token/>

        <table border="1">

            <tr>

                <td>Name:</td>

                <td>

                    <input type="text" name="name"/>

                </td>

            </tr>



            <tr>

                <td>Password:</td>

                <td>

                    <input type="password" name="password"/>

                </td>

            </tr>



            <tr rowspan="2">

                <td>

                    <input type="submit" value="Submit" onclick="return token2(this);"/>

                </td>

                <td>

                    <input type="reset" value="Reset"/>

                </td>

            </tr>

        </table>

    </form>



</body>

</html>

Html代码

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

    pageEncoding="UTF-8"%>

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">

<html>

<head>

<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">

<title>Insert title here</title>

</head>

<body>



    注册成功!



</body>

</html>

Html代码

package com.syh.servlet;



import java.io.IOException;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;





public class LoginServlet 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 {



        try {

            Thread.sleep(3000) ;

        } catch (InterruptedException e) {

            e.printStackTrace();

        }



        try {

            //模拟网速

            Thread.sleep(1000);

        } catch (InterruptedException e) {

            e.printStackTrace();

        }



        //1. 检验 Token 是否可用

        boolean flag = TokenProcessor.getInstance().isTokenValid(request) ;

        //2. 去除 Session 中的 Token 标记

        if(flag) {

            TokenProcessor.getInstance().resetToken(request) ;

        }else {

            System.out.println("重复提交");

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

            return ;

        }



        String name = request.getParameter("name") ;

        System.out.println("添加成功-->" + name);



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

    }



}

Java代码

package com.syh.servlet;



import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpSession;

import javax.servlet.jsp.JspException;

import javax.servlet.jsp.PageContext;

import javax.servlet.jsp.tagext.SimpleTagSupport;



import java.io.IOException;

import java.security.MessageDigest;

import java.security.NoSuchAlgorithmException;



public class TokenProcessor extends SimpleTagSupport{



    @Override

    public void doTag() throws JspException, IOException {



        PageContext pageContext = (PageContext) getJspContext();

        HttpServletRequest request = (HttpServletRequest) pageContext.getRequest();



        String output = "<input type='hidden' name='" + TOKEN_KEY + "' value='" + saveToken(request) + "'/>";

        pageContext.getOut().print(output);

    }



    public static final String TAGLIB_PACKAGE = "org.apache.struts.taglib.html";



    public static final String TRANSACTION_TOKEN_KEY =

        "org.apache.struts.action.TOKEN";



    public static final String TOKEN_KEY = TAGLIB_PACKAGE + ".TOKEN";



    private static TokenProcessor instance = new TokenProcessor();



    private long previous;



    public TokenProcessor() {

        super();

    }



    public static TokenProcessor getInstance() {

        return instance;

    }



    public synchronized boolean isTokenValid(HttpServletRequest request) {

        return this.isTokenValid(request, false);

    }



    public synchronized boolean isTokenValid(HttpServletRequest request,

        boolean reset) {

        // Retrieve the current session for this request

        HttpSession session = request.getSession(false);



        if (session == null) {

            return false;

        }



        String saved =

            (String) session.getAttribute(TRANSACTION_TOKEN_KEY);



        if (saved == null) {

            return false;

        }



        if (reset) {

            this.resetToken(request);

        }



        String token = request.getParameter(TOKEN_KEY);



        if (token == null) {

            return false;

        }



        return saved.equals(token);

    }



    public synchronized void resetToken(HttpServletRequest request) {

        HttpSession session = request.getSession(false);



        if (session == null) {

            return;

        }



        session.removeAttribute(TRANSACTION_TOKEN_KEY);

    }



    public synchronized String saveToken(HttpServletRequest request) {

        HttpSession session = request.getSession();

        String token = generateToken(request);



        if (token != null) {

            session.setAttribute(TRANSACTION_TOKEN_KEY, token);

        }



        return token;

    }



    public synchronized String generateToken(HttpServletRequest request) {

        HttpSession session = request.getSession();



        return generateToken(session.getId());

    }



    public synchronized String generateToken(String id) {

        try {

            long current = System.currentTimeMillis();



            if (current == previous) {

                current++;

            }



            previous = current;



            byte[] now = new Long(current).toString().getBytes();

            MessageDigest md = MessageDigest.getInstance("MD5");



            md.update(id.getBytes());

            md.update(now);



            return toHex(md.digest());

        } catch (NoSuchAlgorithmException e) {

            return null;

        }

    }



    private String toHex(byte[] buffer) {

        StringBuffer sb = new StringBuffer(buffer.length * 2);



        for (int i = 0; i < buffer.length; i++) {

            sb.append(Character.forDigit((buffer[i] & 0xf0) >> 4, 16));

            sb.append(Character.forDigit(buffer[i] & 0x0f, 16));

        }



        return sb.toString();

    }

}

Xml代码

<?xml version="1.0" encoding="UTF-8" ?>



<taglib xmlns="http://java.sun.com/xml/ns/j2ee"

    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

    xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-jsptaglibrary_2_0.xsd"

    version="2.0">



  <description>MyTag 1.0 core</description>

  <display-name>MyTag core</display-name>

  <tlib-version>1.0</tlib-version>

  <short-name>syh</short-name>

  <uri>http://java.syh.com/jsp/syh/core</uri>



    <tag>

        <name>token</name>

        <tag-class>com.syh.servlet.TokenProcessor</tag-class>

        <body-content>empty</body-content>

    </tag>







</taglib>

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标签： 表单 struts 重复提交

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