Java 在 JSP 中，如何使用 JSTL 检查请求中是否存在某些会话属性？
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In JSP, how can i check, using JSTL, if certain session attribute exists in request?
提问by Vladimir
This is code in servlet:
这是servlet中的代码：
HttpSession session = request.getSession(true);
session.setAttribute("user", user);
I am forwarding request to JSP, where i want to check if there is session scoped user parameter attached.
我正在将请求转发到 JSP，我想在其中检查是否附加了会话范围的用户参数。
<c:if test="${??? - check if user is attached to request}">
/ /message
</c:if>
采纳答案by JB Nizet
<c:if test="${sessionScope.user != null}">
There is a user **attribute** in the session
</c:if>
回答by TheDude
I think you mean checking the session scope right?
我认为您的意思是检查会话范围对吗？
<c:if test="${!empty sessionScope.user}">
回答by Nidhish Krishnan
you can do that by using the following code
您可以使用以下代码来做到这一点
Setting session in Servlet
设置会话 Servlet
HttpSession session = request.getSession();
session.setAttribute("user", user);
Access session value by ELin JSP
通过ELin访问会话值JSP
<p>${sessionScope:user}</p>
Checking the session in JSPusing JSTL
正在JSP使用中检查会话JSTL
<c:if test="${sessionScope:user != null}" >
session value present......
</c:if>
