Session Management using Google User on Google App Engine

Code to be inserted in every JSP Page


HttpSession s = request.getSession();
if (s.getAttribute("logged")==null){
s.setAttribute("from",request.getRequestURI());
response.sendRedirect("/login");
}
else {
s.setAttribute("from",request.getRequestURI());
%>Logout<%
//UserService userSer = (UserService)s.getAttribute("userSer");
}

Login.java


public class Login extends HttpServlet {
    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws IOException {
     UserService userSer=UserServiceFactory.getUserService();
     User u=userSer.getCurrentUser();
     HttpSession s=request.getSession();
     String from=(String)s.getAttribute("from");
     s.setAttribute("logged","yes");
     s.setAttribute("userSer", userSer);
     response.sendRedirect(userSer.createLoginURL(from));
    
    }
}

Logout.java


public class Logout extends HttpServlet {
    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws IOException {
    
     HttpSession s = request.getSession();
     String from=(String)s.getAttribute("from");
     UserService us=(UserService)s.getAttribute("userSer");
     s.invalidate();
     response.sendRedirect(us.createLogoutURL("/index.html"));
    
    }
}