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web.xml:
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="3.0"
xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd">
<filter>
<filter-name>tokenFilter</filter-name>
<filter-class>com.huawei.filter.TokenFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>tokenFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
<servlet>
<servlet-name>testServlet</servlet-name>
<servlet-class>com.huawei.token.TestServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>testServlet</servlet-name>
<url-pattern>/testServlet</url-pattern>
</servlet-mapping>
</web-app>
filter:
package com.huawei.filter;
import java.io.IOException;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
public class TokenFilter implements Filter{
@Override
public void destroy() {
}
@Override
public void doFilter(ServletRequest req, ServletResponse resp,FilterChain chain) throws IOException, ServletException {
HttpServletRequest request = (HttpServletRequest)req;
HttpServletResponse response = (HttpServletResponse) resp;
String remark = request.getParameter("remark");
if(remark!=null&&remark.equals("token")){
HttpSession session = request.getSession();
String tokenResult = (String) session.getAttribute("tokenResult");
String tokenValue = request.getParameter("tokenValue");
if(tokenValue.equals(tokenResult)){//说明是第一次提交
session.removeAttribute("tokenResult");
chain.doFilter(request,response);
}else{
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
System.out.println(basePath);
response.sendRedirect(basePath+"/error.jsp");
return;
}
}else{
chain.doFilter(request,response);
}
}
@Override
public void init(FilterConfig filterConfig) throws ServletException {
}
}
token:
package com.huawei.token;
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 TestServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {
doPost(request, response);
}
public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {
String uname=request.getParameter("uname");
System.out.println("==============TestServlet================"+uname);
request.getRequestDispatcher("ok.jsp").forward(request, response);
return;
}
}
jsp:
error.jsp:
<%@ 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%>">
<meta http-equiv="Content-Type" content="text/html;charset=UTF-8">
<title>This is my JSP page</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
</head>
<body>
<h1>禁止重复提交</h1>
</body>
</html>
index.jsp:
<%@ 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%>">
<meta http-equiv="Content-Type" content="text/html;charset=UTF-8">
<title>This is my JSP page</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
</head>
<body>
<%
session.setAttribute("tokenResult", UUID.randomUUID().toString());
%>
<form action="testServlet">
<input name="uname" value="lisi" /><br>
<input type="hidden" name="tokenValue" value="${tokenResult}"/>
<input type="hidden" name="remark" value="token" />
<input type="submit" value="提交">
</form>
</body>
</html>
ok.jsp:
<%@ 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%>">
<meta http-equiv="Content-Type" content="text/html;charset=UTF-8">
<title>This is my JSP page</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
</head>
<body>
<h1>提交成功</h1>
</body>
</html>
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原文地址：http://www.cnblogs.com/hwgok/p/5540675.html
