found out the way now, just using new Expectations() syntax.
context.checking(new Expectations() {{
oneOf(req).getParameter("sitename"); will(returnValue(siteName));
oneOf(req).getParameter("pagename"); will(returnValue(pageName));
oneOf(req).getParameter("textcolor"); will(returnValue(textColor));
oneOf(req).getParameter("buttoncolor"); will(returnValue(buttonColor));
oneOf(req).getParameter("bordercolor"); will(returnValue(borderColor));
oneOf(req).getParameter("subscribetext"); will(returnValue(subscribeText));
oneOf(req).getParameter("unsubscribetext"); will(returnValue(unsubscribeText));
allowing(req).getRequestDispatcher(result);
allowing(req).getRequestURL();
}});