How can I check for a presence of a logged in user in a session using JSTL?

Question

I want to check if the user is logged in or not using JSTL.

I tried the following code:

<c:if test="${sessionScope.logged_in == null}">
      <c:redirect url="index.jsp"></c:redirect>
</c:if>

I have also tried the following code but it throws an IllegalStateException:

<c:if test="${empty user}">
    <b>you are not logged in</b>
<c:redirect url="index.jsp"></c:redirect>
</c:if>

but it is not working.

How can I implement the following code in JSTL:

<%
   String logged_in = (String) session.getAttribute("logged_in");
   if (logged_in == null) {
        response.sendRedirect("index.jsp");
   }
%>

The @BalusC suggested variant (see the example in his link) is the more preferred solution. It is the common practice to use servlet filters for the things like a login check. But of course it's up to you ... — informatik01, Feb 28 '13 at 23:20
@informatik01 The question is about JSTL but not about filters. — Alex, Feb 28 '13 at 23:32
@Alexey Yes, I agree that you gave the answer for the question he asked in the last sentence. But the **preferred and most common** way of checking if user is logged in or not is by using servlet filters. I just gave him a hint, you know — informatik01, Feb 28 '13 at 23:35
@informatik01 In this case it can be some interceptor (spring mvc) for example because we don't know anything about backend for this question. — Alex, Feb 28 '13 at 23:41
@Alexey Maybe, although no mentioning of Spring was seen in the question. btw interesting answer here as well: [Spring HandlerInterceptor vs Servlet Filters](http://stackoverflow.com/a/8006367/814702). Again, as I understand, BalucS just gave him a link to help him see the direction to move for. And I agreed with that. No worries ) — informatik01, Feb 28 '13 at 23:45

score 3 · Accepted Answer · answered Feb 12 '13 at 01:55

3

Try this:

<c:if test="${empty logged_in}">
<c:redirect url="index.jsp"></c:redirect>
</c:if>

answered Feb 12 '13 at 01:55

Alex

1 Answers1