struts2 access session Id

Hi
I have a problem with Struts 2.
I am looking for a way to access httpsession id?

I have tried using ActionContext.getContext().getSession().get("id") but it
returns null. i 've read there is a possibility to use Servlet Config
Interceptor<http://www.opensymphony.com/webwork/wikidocs/Servlet%20Config%20Interceptor.html>
but i would not like to do it.

Any help

milo