First, there may be no such parameter  named as
"viewType". I mean check the name and spellings.

Secondly, try following code. In the following code  i
have typecast the request  object into
"HttpServletRequest".

HttpServletRequest request =
(HttpServletRequest)pageContext.getRequest();
String viewType = request.getParameter("viewType");

Try this 'coz i have done this many times by this
method.