JSP EL ${stuff} syntax not working

问题:

I have two problems. The first one is that I'm using JSP and that I can't solve. The second one is that I'm getting an odd behavior.

When I put this in the doGet() method of my servlet

req.setAttribute("test", "SARASA");
req.getRequestDispatcher("WEB-INF/main.jsp").forward(req, resp);

And this in "WEB-INF/main.jsp":

<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
<%= request.getAttribute("test") %>
<c:out value="${test}"/>

The output is:

SARASA ${test}

I don't know what I'm doing wrong... what can be the reason for this?

---

Update: I solved it adding

<%@ page isELIgnored="false" %>

In each JSP where I needed it. Oddly, I didn't needed that in another project using some very similar web.xml and pom.xml files (I'm using maven).

回答1:

Your web.xml is probably referencing the Servlet 2.3 spec, in which isELIgnored is set to true by default. If you reference the Servlet 2.4 spec instead, isELIgnored will be set to false by default.

If you want to reference the Servlet 2.4 spec, your web.xml header should look something like this:

<web-app xmlns="http://java.sun.com/xml/ns/j2ee"
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd"
     version="2.4">