String redirect = ParamUtil.getString(actionRequest , "redirect");
   actionResponse.sendRedirect(redirect);

ThemeDisplay themeDisplay = (ThemeDisplay) actionRequest.getAttribute(WebKeys.THEME_DISPLAY);
PortletURL url = PortletURLFactoryUtil.create(PortalUtil.getHttpServletRequest(actionRequest), "8", themeDisplay.getPlid(),
PortletRequest.RENDER_PHASE);
url.setParameter("struts_action", "/calendar/view");
actionResponse.sendRedirect (url.toString()) ;