@Controller
@RequestMapping(value = "/login")
public class Login{

    @RequestMapping
    public ModelAndView mainPage(HttpServletRequest request){

        request.getSession().setAttribute("testSession", "Session test");

        return new ModelAndView("/login");

    }

    @RequestMapping(value = "/check")
    public View check(HttpServletRequest request){

        System.out.println(request.getSession(false)); //null

        return new RedirectView("/login");

    }

}