How can I check whether session was timed out?
How can I check in an error page whether the sessi开发者_Python百科on was timed out?
I have tried
<c:choose>
<c:when test="${empty pageContext.request.session}">
//do smth
</c:when>
<c:otherwise>
//do smth
</c:otherwise>
</c:choose>
but it doesn't work.
There is really no reliable way to detect that. You could fiddle with some session based token as request parameter in all links/forms and validate it in the filter, but that's fully spoofable and not really SEO friendly.
Best what you could do is to add a <meta http-equiv="refresh"> tag to the <head> of the master template which redirects the page to the session timeout error page automatically whenever the session is expired. Since you're using a shared error page, you could pass the condition as a request parameter:
<meta http-equiv="refresh" content="${pageContext.session.maxInactiveInterval};url=error.jsp?type=timeout" />
and check it in the error.jsp as follows:
<c:choose>
<c:when test="${param.type == 'timeout'}">
<p>Your session has been timed out.</p>
</c:when>
<c:otherwise>
<!-- Handle default case here. -->
</c:otherwise>
</c:choose>
Oh, yes, ${pageContext.session} is legitimately valid. The ${pageContext.request.session} is just an unnecessary detour. Check the PageContext javadoc for all available getters.
I don't think that will work the way you want. try ${pageContext.request.session.new}
If you don't specify in the <%@page session="false"%> tag I don't think it creates a new session so your first code /might/ work but I would stress checking in the fashion I indicated above.
.isNew() is defined on HttpSession
request.getSession() will always return session, thus your approach will not work. If your requirement is not create a session, when does not exist, use a custom tag.
If you want to create a session when it does not exist, and you want to know if the the request is joining the session/creating a new session. Use ${pageContext.request.session.new}.
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