Struts标签判断当前用户是否存在

<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
<%@ taglib prefix="s" uri="/struts-tags" %>


<s:if test="null==#session.weblogin||#session.weblogin.isEmpty()">
        <a id="head" href="login.jsp"></a>
    </s:if>
    <s:else>
        <a id="head" href="ucenter.do"></a>
    </s:else>