如果用户尚未登录Java servlet，如何重定向到jsp登录页面？

Question

I have wrote an web application using JSP in eclipse. 我已经在Eclipse中使用JSP编写了一个Web应用程序。 It has login page and other pages. 它具有登录页面和其他页面。 After i deployed and trying to access the other pages, i am able to access without login using login page. 部署并尝试访问其他页面后，无需登录即可使用登录页面访问。 So i want to redirect to login page whenever user trying to access other pages url before logged in through login page already. 因此，只要用户尝试通过登录页面登录之前尝试访问其他页面的URL，我想重定向到登录页面。 How to do that? 怎么做？ If anyone help me on this one will be appreciated. 如果有人在这方面帮助我，将不胜感激。

Thanks 谢谢

Answer 1

You can even look for : Click here . 您甚至可以寻找：单击此处。 You have to implement a logic which checks user credentials (login username or login password) details on every page . 您必须实现一种逻辑，该逻辑检查每个页面上的用户凭据（登录用户名或登录密码）详细信息。 if details present then process it further else redirect to Error page . 如果存在详细信息，则进行进一步处理，否则重定向到错误页面。 for now i have implemented a logic which set attribute on login after login it sets all the data into session if not set error message into session . 现在我已经实现了一种逻辑，该逻辑在登录后设置登录时的属性，如果未将错误消息设置为session，则它将所有数据设置为session。 usually we will store UserClass into session since it is for your knowledge that's why i have added two attribute into session . 通常我们会将UserClass存储到session中，因为据您所知，这就是我在session中添加了两个属性的原因。

LoginServlet.java LoginServlet.java

package com.servlets;

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;

@WebServlet("/LoginServlet")
public class LoginServlet extends HttpServlet {
private static final long serialVersionUID = 1L;

public LoginServlet() {
    super();
    // TODO Auto-generated constructor stub
}

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    // TODO Auto-generated method stub
    response.getWriter().append("Served at: ").append(request.getContextPath());
}

/**
 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
 */
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    // TODO Auto-generated method stub
    String uname=request.getParameter("uname");
    String pword=request.getParameter("pword");
    if(null!=uname && uname!="" && pword!=null && pword!=""){
        HttpSession  session=request.getSession(true);
        session.setAttribute("uname", uname);
        session.setAttribute("pword", pword);
        response.getWriter().append("Login SucessFully");
    }else{
          response.sendRedirect("index.jsp"); //error
          HttpSession  session=request.getSession(true);
            session.setAttribute("errorMessage", "Login Failed ");

    }
    //doGet(request, response);
}

}

index.jsp : index.jsp：

  <!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=windows-1256">
<title>Login Page</title>
</head>
<%
String errorMessage = (String) session.getAttribute("errorMessage");
if (null !=errorMessage) { %>
<h4> <%=errorMessage %></h4>
<%}
%>
<body>
<form action="LoginServlet"  method="post" >
    Please enter your username <input type="text" name="uname" id="uname" />
 <br>
    Please enter your password <input type="text" name="pword" id="pword" />
    <input type="submit" value="submit">
 </form>
 </body>
</html>

PostLogin.jsp PostLogin.jsp

 <%@ page language="java" contentType="text/html; charset=ISO-8859-1"
pageEncoding="ISO-8859-1"%>
  <!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=ISO-8859-1">
 <title>Simple Page which can't be access without Login</title>
 </head>
  <%
    String uname = (String) session.getAttribute("uname");
    if (null == uname) {
    session.setAttribute("errorMessage", "Login Failed ");
    response.sendRedirect("userLogged.jsp");
    }
 %>
 <body>
 <h4>Simple Page which can be access without Login </h4>
 </body>
 </html>

Hope this is helpful for you Good luck . 希望这对您有所帮助。 let me know if you want other details too 让我知道您是否还需要其他详细信息

Answer 2

Put the following code in your web.xml file. 将以下代码放入您的web.xml文件中。

 <welcome-file-list>
        <welcome-file>login.jsp</welcome-file>
 </welcome-file-list>

So that when run the application it will show the first page as login.jsp. 这样，在运行该应用程序时，它将第一页显示为login.jsp。 Which means the authentication will go on. 这意味着身份验证将继续。

如果用户尚未登录Java servlet，如何重定向到jsp登录页面？

问题描述

2 个解决方案

解决方案1
1 已采纳 2017-10-27 04:54:57

解决方案2
0 2017-10-27 09:32:34

如果用户尚未登录Java servlet，如何重定向到jsp登录页面？

问题描述

2 个解决方案

解决方案1 1 已采纳 2017-10-27 04:54:57

解决方案2 0 2017-10-27 09:32:34

解决方案1
1 已采纳 2017-10-27 04:54:57

解决方案2
0 2017-10-27 09:32:34