GetServletContextName returns NULL in a filter ??

Question

I have set a context for this web app in its xml file in the conf/Catalina/Locahost folder of tomcat 5.0.16
However, when trying to get the context name when in a filter, I get null. Can anyone explain why. The code is below:-
public void attributeAdded(HttpSessionBindingEvent event)
HttpSession session = event.getSession();
String contextname = session.getServletContext().getServletContextName();
Is this because I have the jar file containing this in my common/lib folder, even though I am accessing it via a webapp context ?

Answer 1

I found the answer to my question with just a little more looking. It is on the HttpServletRequest. The method is getContextPath(). According to the javadocs:
"Returns the portion of the request URI that indicates the context of the request. The context path always comes first in a request URI. The path starts with a "/" character but does not end with a "/" character. For servlets in the default (root) context, this method returns "". The container does not decode this string.
Returns:
a String specifying the portion of the request URI that indicates the context of the request"