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When deploying my application on a Hudson Server (windows machine) , I'm having problems calling java.exe because my class-path is too long -- Windows taps out after certain length.

The classpath is basically hundreds of Jar files separated by semicolons

Assume the following classpath would be too large if each jar is explicitly listed in the classpath: 

<path id="classpath.project">
    <fileset dir="lib" includes="**/*.jar" />
</path>

What can I do in ant to shorten my classpath?

Joachim Sauer
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Shawn
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  • Look at this question about using classpath wildcards. [Setting Multiple Jars In Java Classpath][1] [1]: http://stackoverflow.com/questions/219585/setting-multiple-jars-in-java-classpath – Dusty Pearce Sep 02 '11 at 14:21

2 Answers2

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Since Java 6 supports wildcards in the classpath. Specifically it supports using * to refer to all jar files in a given directory (note: not *.jar!):

Using * as the classpath means "all jar files in the current directory" and using lib/* means "all jar files in the directory lib/".

Unless you have tons of directories, this should be sufficient. I don't know how to make use of that fact from Ant, however.

Joachim Sauer
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You can google for OneJar. If you want to do it yourself, then generate an "empty" jar file that only has a manifest. Add a "Class-Path: a.jar, another.jar, bla-blub.jar" line containing all needed jars to the manifest. (Google for "manifest Class-Path") (can be done with ant) Provided that all jars are deployed aas usually you now only need your "empty" jar file on the classpath, as the JVM will now use the manifest to find all other jars.

Angel O'Sphere
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  • Note that `-classpath` is supporting both relative and absolute paths to libs, but `Class-Path` in manifest file can utilize only relative paths. This may cause some pain when your build tools use absolute paths only (like Maven). – Vlastimil Ovčáčík Oct 28 '15 at 09:11