jspelweb.xml

EL expressions not evaluated in JSP

There's a small problem with my servlets/jsp web application. I'm trying to use jstl in jsp page. When I use any tag for example:

<c:out value="${command}"/>

it shows me 

${command}

in my browser instead of parameter 'command' value. I'm using maven (and I guess the problem is here). Here is pom xml dependencies:

<dependency>
  <groupId>javax.servlet</groupId>
  <artifactId>javax.servlet-api</artifactId>
  <version>3.0.1</version>
  <scope>provided</scope>
</dependency>
<dependency>
  <groupId>jstl</groupId>
  <artifactId>jstl</artifactId>
  <version>1.2</version>
</dependency>

my web.xml declaration tag:

<web-app xmlns="http://java.sun.com/xml/ns/javaee"
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
     version="3.0">

and jsp part:

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>

<html>

<head>
<title>Parsing results</title>
<link type="text/css" rel="stylesheet" href="css/page.css"/>
<link type="text/css" rel="stylesheet" href="css/table.css"/>
</head>

<body>
<h2 align="center">Results of 
parsing. Parsing method = <c:out value="${command}"/></h2>.......

EDIT: Code, which sets command value, is simple:

request.setAttribute("command", parser.getName());

then goes 

request.getRequestDispatcher(redir).forward(request, response);

Tell me please, what I'm doing wrong! Thx!

Solution

  • Yes, i have doctype in web.xml <!DOCTYPE web-app PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN" "java.sun.com/dtd/web-app_2_3.dtd"; >

    Remove that <!DOCTYPE> from web.xml and make sure that the <web-app> is declared conform Servlet 2.4 or newer and all should be well.

    A valid Servlet 3.0 (Tomcat 7, JBoss AS 6-7, GlassFish 3, etc) compatible web.xml look like below in its entirety, without any <!DOCTYPE>:

    <?xml version="1.0" encoding="UTF-8"?>
<web-app 
    xmlns="http://java.sun.com/xml/ns/javaee"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
    version="3.0">

    <!-- Config here. -->

</web-app>

    For Servlet 3.1 (Tomcat 8, WildFly 8-11, GlassFish/Payara 4, etc) it look like below:

    <?xml version="1.0" encoding="UTF-8"?>
<web-app 
    xmlns="http://xmlns.jcp.org/xml/ns/javaee"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"
    version="3.1">

    <!-- Config here. -->

</web-app>

    For Servlet 4.0 (Tomcat 9, WildFly 12-21, GlassFish/Payara 5, etc) it look like below:

    <?xml version="1.0" encoding="UTF-8"?>
<web-app 
    xmlns="http://xmlns.jcp.org/xml/ns/javaee"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
    version="4.0">

    <!-- Config here. -->

</web-app>

    For Servlet 5.0 (Tomcat 10.0, WildFly 22-26, GlassFish/Payara 6, etc) it look like below:

    <?xml version="1.0" encoding="UTF-8"?>
<web-app 
    xmlns="https://jakarta.ee/xml/ns/jakartaee"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="https://jakarta.ee/xml/ns/jakartaee https://jakarta.ee/xml/ns/jakartaee/web-app_5_0.xsd"
    version="5.0">

    <!-- Config here. -->

</web-app>

    For Servlet 6.0 (Tomcat 10.1, WildFly 27+, GlassFish/Payara 7, etc) it look like below:

    <?xml version="1.0" encoding="UTF-8"?>
<web-app 
    xmlns="https://jakarta.ee/xml/ns/jakartaee"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="https://jakarta.ee/xml/ns/jakartaee https://jakarta.ee/xml/ns/jakartaee/web-app_6_0.xsd"
    version="6.0">

    <!-- Config here. -->

</web-app>

    When using JSTL 1.1 or newer, you need to assure that your web.xml is declared in such way that the webapp runs in at least Servlet 2.4 modus, otherwise EL expressions won't work in the webapp.

    When still having a Servlet 2.3 or older <!DOCTYPE> or <web-app> in web.xml, even though you already have a Servlet 2.4 or newer XSD, then it would still be forced to run in Servlet 2.3 or older modus, causing the EL expressions to fail.

    The technical reason is, EL was originally part of JSTL 1.0 and not available in Servlet 2.3 / JSP 1.2 and older. In JSTL 1.1, EL was removed from JSTL and integrated in JSP 2.0, which goes along with Servlet 2.4. So, if your web.xml is declared to run the webapp in Servlet 2.3 or older modus, then JSP would expect to find EL in JSTL library, but this would in turn fail if it's a newer JSTL version, lacking EL.

    See also: