Passing session attributes through forward and redirect
Question
I am trying to figure out how to use sessions using JSTL, so I began by trying to set a session attribute in a Jsp and passing that attribute to another Jsp within the same application and retrieving it there.
I set the attribute and used the dispatcher to get to the other servlet, in another attempt I used sendRedirect to forward the request to the other servlet.
Here is the first Jsp (where I set the attribute):
<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
pageEncoding="ISO-8859-1"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<html>
<body>
<c:set var="session" scope="session" value="test"></c:set>
<%
response.sendRedirect("session.jsp"); // I know I could use the JSTL tag forward
%>
</body>
</html>
In the other Jsp ("session.jsp"):
<%
HttpSession s = request.getSession();
if(s.isNew())
out.print("new session " );
out.print(s.getAttribute("session"));
%>
When I use sendRedirect the result is "test" , meaning that the session wasn't newly created. However, when I use forward (dispatcher) the result is "new session test" .
I don't know the reason for such behavior, although it would make sense if the results were reversed.
1 answers
solution1
5 ACCPTED 2013-07-12 16:11:26
when you use redirect the server says to client (user browser) that please send a new request for me. then user browser request new page. in this state we have 2 request. see following picture:
but forward request occured in the server. if you have n time forward a request it back one request. see following picture:
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