找不到“http://java.sun.com/jsp/jstl/core”的标签库描述符

问题描述

我已经把它放在了JSP页面的最上方：

 <％@ taglib prefix =c uri =http://java.sun.com/jsp/jstl/core％> 
  

我已将JSTL JAR文件放在 WEB-INF / / code>目录。但是，仍然，JSP无法解析taglib。我得到以下错误：

I am using Eclipse Juno and the project structure is shown below:

解决方案

Based on one of your previous questions you're using Tomcat 7. In that case you need JSTL 1.2. However, you've there a jstl.jar file while JSTL 1.2 has clearly the version number included like so jstl-1.2.jar. The sole filename jstl.jar is typical for JSTL 1.0 and 1.1. This version requires a standard.jar along in /WEB-INF/lib which contains the necessary TLD files. However, in your particular case the standard.jar is clearly missing in /WEB-INF/lib and that's exactly the reason why the taglib URI couldn't be resolved.

To solve this you must remove the wrong JAR file, download jstl-1.2.jar and drop it in its entirety in /WEB-INF/lib. That's all. You do not need to extract it nor to fiddle in project's Build Path.

Don't forget to remove that loose c.tld file too. It absolutely doesn't belong there. This is indeed instructed in some poor tutorials or answers elsewhere in the Internet. This is a myth caused by a major misunderstanding and misconfiguration. There is never a need to have a loose JSTL TLD file in the classpath, also not in previous JSTL versions.

In case you're using Maven, use the below coordinate:

<dependency>
    <groupId>javax.servlet</groupId>
    <artifactId>jstl</artifactId>
    <version>1.2</version>
</dependency>

You should also make sure that your web.xml is declared conform at least Servlet 2.4 and thus not as Servlet 2.3 or older. Otherwise EL expressions inside JSTL tags would in turn fail to work. Pick the highest version matching your target container and make sure that you don't have a <!DOCTYPE> anywhere in your web.xml. Here's a Servlet 3.0 (Tomcat 7) compatible example:

<?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>

See also:

• Our JSTL wiki page (you can reach there by hovering the mouse on jstl and clicking info link)
• How to install JSTL? The absolute uri: http://java.sun.com/jstl/core cannot be resolved

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