String userId = (String)httpServletRequest.getSession().getAttribute("userId");
        
        try{
            if(userId != null){               
                filterChain.doFilter(request, response);
            }
            else{
                httpServletResponse.sendRedirect("http://localhost:8080/Medinet/login.do");
            }
        }
        catch(Exception ex)
        {
            ex.printStackTrace();
        }