Eclipse “cannot find the tag library descriptor” for custom tags (not JSTL!)

Question

I have a Java EE project which build fine with Ant, deploys perfectly to JBoss, and runs without any trouble. This project includes a few custom tag librari

Answer 1

You can simply go to Build Path -> Add Libraries and for the library type to add select "Server Runtime." Click Next and select a server runtime to add to the classpath and the problem goes away if jstl.jar and standard.jar are in your server's classpath.

Answer 2

If your tld's are on the classpath, typically under the WEB-INF directory, the following two tips should resolve the issue (irrespective of your environment setup):

1. Ensure that the <uri> in the TLD and the uri in the taglib directive of your jsp pages match. The <uri> element of the tld is a unique name for the tag library.

2. If the tld does not have a <uri> element, the Container will attempt to use the uri attribute in the taglib directive as a path to the actual TLD. for e.g. I could have a custom tld file in my WEB-INF folder and use the path to the this tld as the uri value in my JSP. However, this is a bad practice and should be avoided since the paths would then be hardcoded.

Answer 3

It turns out that the cause was that this project wasn't being considered by Eclipse to actually be a Java EE project at all; it was an old project from 3.1, and the Eclipse 3.5 we are using now requires several "natures" to be set in the project configuration file.

<natures>
    <nature>org.eclipse.jdt.core.javanature</nature>
    <nature>InCode.inCodeNature</nature>
    <nature>org.eclipse.dltk.javascript.core.nature</nature>
    <nature>net.sf.eclipsecs.core.CheckstyleNature</nature>
    <nature>org.eclipse.wst.jsdt.core.jsNature</nature>
    <nature>org.eclipse.wst.common.project.facet.core.nature</nature>
    <nature>org.eclipse.wst.common.modulecore.ModuleCoreNature</nature>
    <nature>org.eclipse.jem.workbench.JavaEMFNature</nature>
</natures>

I was able to find the cause by creating a new "Dynamic Web Project" which properly read its JSP files, and diffing against the config of the older project.

The only way I could find to add these was by editing the .project file, but after re-opening the project, everything magically worked. The settings referenced by pribeiro, above, weren't necessary since the project already conformed to the default settings.

Both pribeiro and nitind's answers gave me ideas to jumpstart my search, thanks.

Is there a way of editing these "natures" from within the UI?

Answer 4

Check the two libraries in F:\apache-tomcat-7.0.21\webapps\examples\WEB-INF\lib:

1. jstl.jar
2. standard.jar

Answer 5

well you need to understand there are always two things the API and the implementation (mind the gradle format of the following code)

compile group:'javax.servlet.jsp.jstl', name:'javax.servlet.jsp.jstl-api', version:'1.2.1'

compile group:'org.glassfish.web', name:'javax.servlet.jsp.jstl',version:'1.2.1'

so If you're using a servlet container with no jstl support then of course it will not provide both of them, a mistake which I made is that I only put the first one, but if you're using full stack application server i.e glassfish then glassfish will have both of them already inside.

Answer 6

A lot depends on what kind of project it is. WTP's JSP support either expects the JSP files to be under the same folder that's the parent of the WEB-INF folder (src/web, which it will then treat as "/" to find TLDs), or to have project metadata set up to help it know where that root is (done for you in a Dynamic Web Project through Deployment Assembly). How are you referring to the TLD file, and where is the JSP file located?

And maybe I missed the original post to the Eclipse forums; the one I saw was posted a full day after this one.