标签：system proc nano ati common 不同 print bool 创建
在服务器端生成一个唯一的随机标识号，专业术语称为Token(令牌)，同时在当前用户的Session域中保存这个Token。然后将Token发送到客户端的Form表单中，在Form表单中使用隐藏域来存储这个Token，表单提交的时候连同这个Token一起提交到服务器端，然后在服务器端判断客户端提交上来的Token与服务器端生成的Token是否一致，如果不一致，那就是重复提交了，此时服务器端就可以不处理重复提交的表单。如果相同则处理表单提交，处理完后清除当前用户的Session域中存储的标识号。
在下列情况下，服务器程序将拒绝处理用户提交的表单请求：
生成Token的工具类TokenProccessor
package utils; import java.util.Random; import org.apache.commons.codec.binary.Base64; public class TokenProccessor { private TokenProccessor(){ } private static final TokenProccessor instance=new TokenProccessor(); public static TokenProccessor getInstance(){ return instance; } public String makeToken(){ //Apache Commons Codec有提供Base64的编码与解码功能 String token=(System.nanoTime()+new Random().nextInt(999999999))+""; byte[] bytes=token.getBytes(); Base64 base64=new Base64(); String s=base64.encodeToString(bytes); System.out.println(s); return s; } // public static void main(String[] args){ // System.out.println(TokenProccessor.getInstance().makeToken()); // } }
创建Servlet，用于生成Token(令牌)和跳转到form.jsp页面
package lala; import java.io.IOException; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import utils.TokenProccessor; public class demo5 extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { String token=TokenProccessor.getInstance().makeToken(); request.getSession().setAttribute("token", token); request.getRequestDispatcher("/form.jsp").forward(request, response); } public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } }
在form.jsp中使用隐藏域来存储Token(令牌)
<html>
<head>
<title>My JSP ‘form.jsp‘ starting page</title>
</head>
<body>
"${pageContext.request.contextPath }"
<form action="${pageContext.request.contextPath }/demo6" method="post">
<input type="hidden" name="token" value="${token }">
username:<input type="text" name="username"><br/>
<input type="submit" value="submit">
</form>
</body>
</html>
处理表单提交
package lala; 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 demo6 extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setContentType("text/html;charset=utf-8"); boolean b=isRepeatSubmit(request); if(b==true){ response.getWriter().write("不要重复提交"); return; } request.getSession().removeAttribute("token"); response.getWriter().write("已提交"); } 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; } public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } }
标签：system proc nano ati common 不同 print bool 创建
原文地址：http://www.cnblogs.com/wqkant/p/6710642.html
