java - JSTL if-then-else session 属性

Question

我在为 jsp 页面编写 if-then-else 条件时遇到一些问题。我认为问题出在我的引述上。是否可以在 javascript 中使用 JSTL？

代码

 <c:choose>
    <c:when test= "'<%=request.getSession().getAttribute("userName")%>' == Guest">
      <button class="btn" id="getCitizens" onclick="DoGuestAccess()" type="button">Guest Access</button>
    </c:when>
    <c:otherwise>
      <button class="btn" id="getCitizens" onclick="DoUsersAccess()" type="button">User Access</button>
    </c:otherwise>
</c:choose>

错误

org.apache.jasper.JasperException: /WEB-INF/jsp/newpage.jsp (line: 485, column: 71) equal symbol expected

Answer 1

这看起来像是测试表达式的问题，请尝试以下操作:

<c:choose>
    <c:when test= "${request.getSession().getAttribute("userName").equals("Guest")}">
        <button class="btn" id="getCitizens" onclick="DoGuestAccess()" type="button">Guest Access</button>
    </c:when>
<c:otherwise>
    <button class="btn" id="getCitizens" onclick="DoUsersAccess()" type="button">User Access</button>
</c:otherwise>

此外，Java 使用 equals 方法进行字符串比较。

或更详细:

<% var userName = request.getSession().getAttribute("userName"); %>
<c:choose>
    <c:when test= "${userName.equals("Guest")}">
        <button class="btn" id="getCitizens" onclick="DoGuestAccess()" type="button">Guest Access</button>
    </c:when>
<c:otherwise>
    <button class="btn" id="getCitizens" onclick="DoUsersAccess()" type="button">User Access</button>
</c:otherwise>