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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!
525
The default mode for JSP pages delivered using a descriptor from Servlet 2.3 or before is to ignore EL expressions; this provides backward compatibility.
The Expression Language (EL) simplifies the accessibility of data stored in the Java Bean component, and other objects like request, session, application etc. There are many implicit objects, operators and reserve words in EL. It is the newly added feature in JSP technology version 2.0.
A JSP expression is used to insert the value of a scripting language expression, converted into a string, into the data stream returned to the client.
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, 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>
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.
68
In my case for web.xml file (version="3.0") I had to run the application on Tomcat server v.8 instead of v.7, otherwise I had the same issue as you. Hope this helps someone...
<?xml version="1.0" encoding="ISO-8859-1" ?>
<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">
Setting <%@ page isELIgnored="false" %> at the top of the page helped to me. Don't know why it was the root of the problem in my case. Not clear why yet.
1
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