Thymleaf如何實(shí)現(xiàn)JSTL對(duì)httpsession中對(duì)象的空值判斷

<c:choose>
            <c:when test="${empty login}">
                <li><a href="../index/loginUI.do"><i class="fa fa-user"></i>注冊(cè)/登錄</a>
                </li>
            </c:when>
            <c:otherwise>
                <li><a href="../index/mycenter.do"><i class="fa fa-user"></i>個(gè)人中心</a></li>
                <li><a href="../index/logout.do"><i class="fa fa-user"></i>退出登錄</a>
                </li>
            </c:otherwise>
        </c:choose>

這是我在JSTL中寫(xiě)的，可以成功運(yùn)行，無(wú)任何異常

 <li><a th:href="@{/login/loginUI}" th:if="${#httpSession.login}eq null"><i class="fa fa-user-md"></i>管理員登陸</a>
            </li>
            <li><a th:href="@{/index/loginUI}" th:if="${#httpSession.login}eq null"><i class="fa fa-user"></i>注冊(cè)/登錄</a>
            </li>
            <li><a th:href="@{/index/mycenter}" th:unless="${#httpSession.login} eq null"><i class="fa fa-user"></i>個(gè)人中心</a></li>
            <li><a th:href="@{/index/logout}" th:if="${#httpSession.login} ne null"><i class="fa fa-user"></i>退出登錄</a>
            </li>

但是我在thymleaf中使用時(shí)總是無(wú)法找到login

然后是我的java代碼

 @RequestMapping("/index")
    public ModelAndView index(HttpServletRequest request, HttpServletResponse response) {
        Page page = new Page("filter_form");
        page.setPageSize(8);
        String currentPage = request.getParameter("page.currentPage");
        if (StringUitl.IsNotNull(currentPage)) {
            page.setCurrentPage(Integer.parseInt(currentPage));
        }
        //拼裝map進(jìn)行查詢(xún)
        Map<String, Object> map = new HashMap<String, Object>();
        map.put("page", page);
        List list = changguanService.getForPage(map);
        //展示的數(shù)據(jù)
        request.setAttribute("list", list);
        request.setAttribute("paging", page.getPageStr());
        System.out.println(page.getPageStr());
        return new ModelAndView("index/index");
    }
 @RequestMapping("/login")
    public void login(HttpServletRequest request, HttpServletResponse response, HttpSession httpSession) throws IOException {
        String pwd = request.getParameter("pwd");
        String no = request.getParameter("no");
        response.setCharacterEncoding("utf-8");
        Login login = (Login) httpSession.getAttribute("login");
        if (login == null) {
            User user = userService.checkUserNo(no, pwd);
            if (user == null) {
                response.setContentType("text/html;charset=utf-8");
                response.getWriter().write("<script>alert('賬號(hào)密碼錯(cuò)誤');</script>");
                response.getWriter().write("<script> window.location='../index/index' ;window.close();</script>");
                response.getWriter().flush();
            }
            login = new Login(user.getId(), user.getName(), "user", "");
            httpSession.setAttribute("login", login);
        }
        response.setContentType("text/html;charset=utf-8");
        response.getWriter().write("<script>alert('登錄成功');</script>");
        response.getWriter().write("<script> window.location='../index/index' ;window.close();</script>");
        response.getWriter().flush();
    }

請(qǐng)問(wèn)thymleaf如何才能實(shí)現(xiàn)jstl的這種直接判斷未創(chuàng)建對(duì)象的空值問(wèn)題