Identify the user from inside the portlet

[Mickael.Lecoq@xxxxxxxx]

Hello,
      I am trying to developp a portlet which uses the info of the users
(name, firstname and mail).
I have tryed the method with USER_INFO:


PortletSession session = portletRequest.getPortletSession();
Object userInfo = portletRequest.getAttribute(RenderRequest.USER_INFO);

 But userInfo is an empty HashMap.

What is the method to get the user informations?

Best Regards,
Mickael Lecoq.