您如何使用JSP表达式语言从会话范围之外的HttpSession获取属性？

Question

Using Jsp expression language I can display a session attribute (a username) on a jsp page stored in the session scope as follows:

<c:out value="${sessionScope.username}" />

This prints the 'username' I previously assigned to the session with the setAttribute method correctly.

However, this does not work when I subsequently assign the HttpSession to a variable. In the below example requestScope.sessionList returns an ArrayList of HttpSessions.

<c:forEach items="${requestScope.sessionList }" var="se" >
    <c:out value="${se.username }" />
</c:forEach>

The above code will result in a javax.el.PropertyNotFoundException: Property 'username' not found on type org.apache.catalina.session.StandardSessionFacade exception. Can someone explain the proper way to access the 'username' attribute in the above scenario?

Answer 1

I don't think there is a solution. Maybe you could use something like the following.

<%@ taglib prefix = "c" uri = "http://java.sun.com/jsp/jstl/core" %>
<%
    session.setAttribute("cars","vehicles");
    session.setAttribute("toys","playthings");
    session.setAttribute("trees","big plants");
%>
<c:forEach items="${pageContext.session.getAttributeNames()}" var="name" >
   ${name} are ${sessionScope[name]}   <br/> 
</c:forEach>