避免表單重複提交--用session實現token機制
阿新 • • 發佈：2019-01-23
直接拿例子來說吧！！
目錄結構
web.xml
<span style="font-size:18px;"><?xml version="1.0" encoding="UTF-8"?> <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0"> <display-name>javaWeb_25</display-name> <welcome-file-list> <welcome-file>index.jsp</welcome-file> </welcome-file-list> </web-app></span>
index.jsp
<span style="font-size:18px;"><%@ 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>index.jsp</title> </head> <body> <form action="<%=request.getContextPath() %>/tokenServlet" method="post"> name: <input type="text" name="name"><br> <input type="submit" value="提交"> </form> </body> </html></span>
TokenServlet.java
<span style="font-size:18px;">package com.dao.chu; 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 TokenServlet */ @WebServlet("/tokenServlet") public class TokenServlet extends HttpServlet { private static final long serialVersionUID = 1L; /** * @see HttpServlet#HttpServlet() */ public TokenServlet() { super(); // TODO Auto-generated constructor stub } /** * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response) */ protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { // TODO Auto-generated method stub String name = request.getParameter("name"); System.out.println("name is :"+name); request.getRequestDispatcher("/success.jsp").forward(request, response); } }
success.jsp
<span style="font-size:18px;"><%@ 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>success.jsp</title>
</head>
<body>
<h1>success page</h1>
</body>
</html></span> 執行效果
提交表單一次，並且重新整理三次頁面
這就是表單的重複提交
重複提交的情況:
①在表單提交到一個Servlet而Servlet又通過請求轉發的方式響應了一個jsp或者是html頁面，此時位址列還保留著Servlet的路徑，在響應頁面點選重新整理。
②在響應頁面沒有到達時，重複點選提交按鈕。
③點選返回，再點選提交
不是重複提交的情況
①點選返回，重新整理原表單頁面，再點選提交
如何避免表單的重複提交
在表單中做一個標記，提交到Servlet時，檢查標記是否存在且是否和預定的標記一致，若一致，則受理請求，並銷燬標記，若不一致，則直接響應提示資訊:重複提交。
1.只寫一個一個隱藏逾
<input type="hidden" name="token" value="daochuwenziyao">，不行。因為無法銷燬標記。
2.標記放在request中
各檔案修改如下:
index.jsp
<span style="font-size:18px;"><%@ 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>index.jsp</title>
</head>
<body>
<form action="<%=request.getContextPath() %>/tokenServlet" method="post">
<%
request.setAttribute("token", "daochuwenizyao");
%>
name: <input type="text" name="name"><br>
<input type="submit" value="提交">
</form>
</body>
</html></span> TokenServlet
package com.dao.chu;
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 TokenServlet
*/
@WebServlet("/tokenServlet")
public class TokenServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* @see HttpServlet#HttpServlet()
*/
public TokenServlet() {
super();
// TODO Auto-generated constructor stub
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
String name = request.getParameter("name");
Object token = request.getAttribute("token");
if (token!=null) {
request.removeAttribute("token");
}else {
response.sendRedirect(request.getContextPath()+"/token.jsp");;
}
}
} token.jsp
<%@ 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>token.jsp</title>
</head>
<body>
<h3>對不起，您已經提交過了</h3>
</body>
</html>也不行，因為表單頁面重新整理後request已經被銷燬,再提交表單是一個新的request。
3.標記放在session中.
index.jsp
<span style="font-size:18px;"><%@ 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>index.jsp</title>
</head>
<body>
<form action="<%=request.getContextPath() %>/tokenServlet" method="post">
<%
session.setAttribute("token", "daochuwenizyao");
%>
name: <input type="text" name="name"><br>
<input type="submit" value="提交">
</form>
</body>
</html></span> TokenServlet.Java
package com.dao.chu;
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 javax.servlet.http.HttpSession;
/**
* Servlet implementation class TokenServlet
*/
@WebServlet("/tokenServlet")
public class TokenServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* @see HttpServlet#HttpServlet()
*/
public TokenServlet() {
super();
// TODO Auto-generated constructor stub
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
HttpSession session = request.getSession();
Object token = session.getAttribute("token");
if (token!=null) {
session.removeAttribute("token");
}else {
response.sendRedirect(request.getContextPath()+"/token.jsp");;
}
}
}經過檢測，此方法可行。
但是有時候我們需要往session中放一個隨機值，後臺如何取得該隨機值呢，這時候需要和隱藏逾搭配使用。
index.jsp
<span style="font-size:18px;"><%@page import="java.util.Date"%>
<%@ 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>index.jsp</title>
</head>
<body>
<%
String tokenValue = new Date().getTime() + "";
session.setAttribute("token", tokenValue);
%>
<form action="<%=request.getContextPath() %>/tokenServlet" method="post">
<input type="hidden" name="token" value="<%=tokenValue %>">
name: <input type="text" name="name"><br>
<input type="submit" value="提交">
</form>
</body>
</html></span> TokenServlet.java
package com.dao.chu;
import java.io.IOException;
import java.util.Date;
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 javax.servlet.http.HttpSession;
/**
* Servlet implementation class TokenServlet
*/
@WebServlet("/tokenServlet")
public class TokenServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* @see HttpServlet#HttpServlet()
*/
public TokenServlet() {
super();
// TODO Auto-generated constructor stub
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
HttpSession session = request.getSession();
String tokenValue = request.getParameter("token");
String token = (String)session.getAttribute("token");
if (token!=null && token.equals(tokenValue)) {
session.removeAttribute("token");
}else {
response.sendRedirect(request.getContextPath()+"/token.jsp");;
}
}
}經過檢測，此方法可行。並且更加滿足需求。
步驟:
1.在原表單頁面，生成一個隨機數token
2.在原表單頁面,把token放在session屬性中
3.在原表單頁面，把token值放在隱藏逾中
4.在目標Servlet中，獲取session和隱藏逾中的token值
5.比較兩個值是否一致，若一致，受理請求且把session中的token屬性清除，若不一致則直接顯示提示頁面:重複提交
使用strus1的工具類來編寫程式碼
strus1的工具類
下載地址
http://download.csdn.NET/download/zhangyw31/2706595
開啟
G:\struts-1.2.9-src\src\share\org\apache\struts\util\TokenProcessor.java
將TokenProcessor複製到專案中,修改兩個常量即可。如果好奇可以在G:\struts-1.2.9-src\src\share\org\apache\struts\Globals中可以搜尋到。
最終我們修改成如下檔案:
TokenProcessor.java
/*
* $Id: TokenProcessor.java 54929 2004-10-16 16:38:42Z germuska $
*
* Copyright 2003-2004 The Apache Software Foundation.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.dao.chu;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;
/**
* TokenProcessor is responsible for handling all token related functionality. The
* methods in this class are synchronized to protect token processing from multiple
* threads. Servlet containers are allowed to return a different HttpSession object
* for two threads accessing the same session so it is not possible to synchronize
* on the session.
*
* @since Struts 1.1
*/
public class TokenProcessor {
private static final String TOKEN_KEY = null;
private static final String TRANSACTION_TOKEN_KEY = null;
/**
* The singleton instance of this class.
*/
private static TokenProcessor instance = new TokenProcessor();
/**
* Retrieves the singleton instance of this class.
*/
public static TokenProcessor getInstance() {
return instance;
}
/**
* Protected constructor for TokenProcessor. Use TokenProcessor.getInstance()
* to obtain a reference to the processor.
*/
protected TokenProcessor() {
super();
}
/**
* The timestamp used most recently to generate a token value.
*/
private long previous;
/**
* Return <code>true</code> if there is a transaction token stored in
* the user's current session, and the value submitted as a request
* parameter with this action matches it. Returns <code>false</code>
* under any of the following circumstances:
* <ul>
* <li>No session associated with this request</li>
* <li>No transaction token saved in the session</li>
* <li>No transaction token included as a request parameter</li>
* <li>The included transaction token value does not match the
* transaction token in the user's session</li>
* </ul>
*
* @param request The servlet request we are processing
*/
public synchronized boolean isTokenValid(HttpServletRequest request) {
return this.isTokenValid(request, false);
}
/**
* Return <code>true</code> if there is a transaction token stored in
* the user's current session, and the value submitted as a request
* parameter with this action matches it. Returns <code>false</code>
* <ul>
* <li>No session associated with this request</li>
* <li>No transaction token saved in the session</li>
* <li>No transaction token included as a request parameter</li>
* <li>The included transaction token value does not match the
* transaction token in the user's session</li>
* </ul>
*
* @param request The servlet request we are processing
* @param reset Should we reset the token after checking it?
*/
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;
}
// Retrieve the transaction token from this session, and
// reset it if requested
String saved = (String) session.getAttribute(TRANSACTION_TOKEN_KEY);
if (saved == null) {
return false;
}
if (reset) {
this.resetToken(request);
}
// Retrieve the transaction token included in this request
String token = request.getParameter(TOKEN_KEY);
if (token == null) {
return false;
}
return saved.equals(token);
}
/**
* Reset the saved transaction token in the user's session. This
* indicates that transactional token checking will not be needed
* on the next request that is submitted.
*
* @param request The servlet request we are processing
*/
public synchronized void resetToken(HttpServletRequest request) {
HttpSession session = request.getSession(false);
if (session == null) {
return;
}
session.removeAttribute(TRANSACTION_TOKEN_KEY);
}
/**
* Save a new transaction token in the user's current session, creating
* a new session if necessary.
*
* @param request The servlet request we are processing
*/
public synchronized void saveToken(HttpServletRequest request) {
HttpSession session = request.getSession();
String token = generateToken(request);
if (token != null) {
session.setAttribute(TRANSACTION_TOKEN_KEY, token);
}
}
/**
* Generate a new transaction token, to be used for enforcing a single
* request for a particular transaction.
*
* @param request The request we are processing
*/
public synchronized String generateToken(HttpServletRequest request) {
HttpSession session = request.getSession();
try {
byte id[] = session.getId().getBytes();
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);
md.update(now);
return toHex(md.digest());
} catch (NoSuchAlgorithmException e) {
return null;
}
}
/**
* Convert a byte array to a String of hexadecimal digits and return it.
* @param buffer The byte array to be converted
*/
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();
}
} 專案結構
index.jsp
<span style="font-size:18px;"><%@page import="com.dao.chu.TokenProcessor"%>
<%@page import="java.util.Date"%>
<%@ 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>index.jsp</title>
</head>
<body>
<form action="<%=request.getContextPath() %>/tokenServlet" method="post">
<!-- 兩個作用
1.產生一個隨機值
2.tokenValue放在session中
-->
<input type="hidden" name="TOKEN_KEY" value="<%=TokenProcessor.getInstance().saveToken(request) %>">
name: <input type="text" name="name"><br>
<input type="submit" value="提交">
</form>
</body>
</html></span> TokenServlet.java
package com.dao.chu;
import java.io.IOException;
import java.util.Date;
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 javax.servlet.http.HttpSession;
/**
* Servlet implementation class TokenServlet
*/
@WebServlet("/tokenServlet")
public class TokenServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* @see HttpServlet#HttpServlet()
*/
public TokenServlet() {
super();
// TODO Auto-generated constructor stub
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
boolean tokenValid = TokenProcessor.getInstance().isTokenValid(request);
if (tokenValid) {
TokenProcessor.getInstance().resetToken(request);
}
else {
response.sendRedirect(request.getContextPath()+"/token.jsp");;
}
}
}可以看出這樣寫程式碼複用性很高。
執行效果
正常情況下可以提交，一旦發生重複提交，則會跳轉到另外一個頁面。
轉自http://blog.csdn.net/daochuwenziyao/article/details/60592188