Hi!
I am testing the "session" object and I don't know why it is losing data when I change the web page. I created a simple software to show the problem:
See the code:
Page index.jsp:
<%@page contentType="text/html" pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Login</title>
</head>
<body>
<form action="" method="post">
<fieldset title="Login">
<p>
Login <input type="text" alt="Login" name="login" maxlength="20" value="" />
</p>
<p>
Password <input type="text" alt="Password" name="pass" maxlength="20" value="" />
</p>
<p>
<input type="submit" value="Send" name="btnSend" />
</p>
<%
if((request.getParameter("login")!=null)&&
(request.getParameter("pass")!=null))
{
String us = request.getParameter("login") +
request.getParameter("pass");
if(us.equals("aaa123"))
{
session.setAttribute("user", us);
session.setMaxInactiveInterval(300); // 5 minutes.
response.sendRedirect("listContacts.jsp");
}
else {
us = null;
session.setAttribute("user",us);
out.println("Type login and password.");
}
}
%>
</fieldset>
</form>
</body>
</html>
When user puts the correct data in the page "index.jsp" he is redirected to the page "listContacts.jsp".
Page listContacts.jsp:
<%@page contentType="text/html" pageEncoding="ISO-8859-9"%>
<%
response.setHeader("Cache-Control", "no-cache, no-store, must-revalidate"); // HTTP 1.1.
response.setHeader("Pragma","no-cache"); // HTTP 1.0.
response.setDateHeader("Expires", 0);
String usSession =(String) session.getAttribute("user");
if(usSession==null || usSession==""){
response.sendRedirect("index.jsp");
}
%>
<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Show Contacts</title>
</head>
<body>
<%
String usLogged = (String) session.getAttribute("user");
if (usLogged != null) {
%>
<fieldset style="text-align: right;">
<p>
User Logged: User
<a href="index.jsp" id="btnLogout" onclick="<%session.invalidate();%>">Logout</a>
</p>
</fieldset>
<%
}
%>
<h1>Contacts List</h1>
<p>Contact A</p>
<p>Contact B</p>
<p>Contact C</p>
<p>Contact D</p>
<p>Contact E</p>
<br />
<p><a href="listContacts2.jsp">Contacts List 2</a></p>
</body>
</html>
In the page "listContacts.jsp" (above) there is a link that, when clicked, send user to page "listContacts2.jsp". Here is the problem, because, when the user click in this link, the "listContacts2.jsp" page is called but, in this moment, the session object has no value. And I don't know why the session object is empty at this moment!!! How the session object is empty, the user is redirected to page "index.jsp" again.
Page listContacts2.jsp:
<%@page contentType="text/html" pageEncoding="ISO-8859-9"%>
<%
response.setHeader("Cache-Control", "no-cache, no-store, must-revalidate"); // HTTP 1.1.
response.setHeader("Pragma", "no-cache"); // HTTP 1.0.
response.setDateHeader("Expires", 0);
String usSession =(String) session.getAttribute("user");
if(usSession==null || usSession==""){
response.sendRedirect("index.jsp");
}
%>
<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Show Conctacts 2</title>
</head>
<body>
<%
String usLogged = (String) session.getAttribute("user");
if (usLogged != null) {
%>
<fieldset style="text-align: right;">
<p>
User Logged: User
<a href="index.jsp" id="btnLogout" onclick="<%session.invalidate();%>">Logout</a>
</p>
</fieldset>
<%
}
%>
<h1>Contacts List 2</h1>
<p>Contact F</p>
<p>Contact G</p>
<p>Contact H</p>
<p>Contact I</p>
<p>Contact J</p>
<br />
<p><a href="listContacts.jsp">Contacts List</a></p>
</body>
</html>
If anyone can help me, I'll be grateful.
Edwar Saliba Júnior
