Why session.getValue is invalid in portlets? Urgent ,help me!!!

Question

I have two JSP pages. Here is first.jsp:
<%@ page import="oracle.portal.provider.v1.*,oracle.portal.provider.v1.http.*" session="true" %>
<center>
Hello, this is the first page<p>
<%
session.putValue("test","aaaaaaaaaaa");
response.sendRedirect(HttpPortletRendererUtil.parameterizeLink(request, PortletRendererUtil.PAGE_LINK, HttpPortletRendererUtil.portletParameter(request, "next_page") + "=second.jsp") );
%>
</center>
Here is second.jsp:
<%@ page import="oracle.portal.provider.v1.*,oracle.portal.provider.v1.http.*" session="true" %>
<center>
Hello, this is the second page<p>
<%
out.println(session.getValue("test"));
%>
</center>
Make first.jsp into a portlet and run it.It goes to the second.jsp and the session value is null!!! why??
If I change first.jsp as below:
<%@ page import="oracle.portal.provider.v1.*,oracle.portal.provider.v1.http.*" session="true" %>
<center>
Hello, this is the first page<p>
<%
session.putValue("test","aaaaaaaaaaa");
%>
<a href="<%=HttpPortletRendererUtil.parameterizeLink(request, PortletRendererUtil.PAGE_LINK, HttpPortletRendererUtil.portletParameter(request, "next_page") + "=second.jsp") %">>second page</a>
</center>
Make first.jsp into a portlet and run it.Manual click the hyper link to second.jsp.Then it show the session value is "aaaaaaaaaaa".
Who can help me???????Thanks a lot!

Answer 1

You are confusing java with javascript.
These two things are not the same.
The lifecycle goes something like this
1 - Request is made to server
2 - Java/JSP runs java code, produces HTML page
3 - java stops running
4 - html is sent to browser, and javascript starts running.
You cannot call java code from browser events (such as onload, onclick, onchange...) The only way to run java code again is to submit a request (normally by submitting a form, or clicking a link. )
If you want a javascript solution, in IE, use the window.setTimeout() method to execute some javascript code after a certain period of time.
A more generic approach would be to use the refresh header. Set the timeout for the refresh header to be 300 seconds. If the user stays on the same page for more than 5 minutes, it will redirect to the new page.
Hope this helps,
evnafets