How can I pass a union to the war lib element? - ant

Question

I am trying to refactor an ant build.xml file to reduce duplication. Previously the file had a bunch of targets something like this:
<war ...>
<lib dir=${lib}">
<include name="foo.jar"/>
<include name="bar.jar"/>
<include name="qux.jar"/>
</lib>
...
</war>
<jar ...>
...
<manifest>
<attribute name="Class-Path" value="foo.jar bar.jar baz.jar"/>
</manifest>
</jar>
Despite the ant documentation, I got it to the point where it looks more like this:
<fileset id="commonLibs1" dir="${lib}">
<include name="foo.jar"/>
<include name="bar.jar"/>
</fileset>
<union id="clientLibs">
<fileset refid="commonLibs1"/>
<fileset dir="${lib}">
<include name="baz.jar"/>
</fileset>
</union>
<war ...>
<lib dir=${lib}">
<include name="foo.jar"/>
<include name="bar.jar"/>
<include name="qux.jar"/>
</lib>
...
</war>
<manifestclasspath property="tmpClassPath" jarfile="./placeholdername.jar">
<classpath>
<resources refid="clientLibs"/>
</classpath>
</classpath>
<jar ...>
...
<manifest>
<attribute name="Class-Path" value="${tmpClasspath}"/>
</manifest>
</jar>
Which is swell. Now I've almost reached my goal of not having all these jar names copied all over the place:
<fileset id="commonLibs1" dir="${lib}">
<include name="foo.jar"/>
<include name="bar.jar"/>
</fileset>
<union id="clientLibs">
<fileset refid="commonLibs1"/>
<fileset dir="${lib}">
<include name="baz.jar"/>
</fileset>
</union>
<union id="serverLibs">
<fileset refid="commonLibs1"/>
<fileset dir="${lib}">
<include name="qux.jar"/>
</fileset>
</union>
<war ...>
<lib refid="serverLibs"/>
...
</war>
<manifestclasspath property="tmpClassPath" jarfile="./placeholdername.jar">
<classpath>
<resources refid="clientLibs"/>
</classpath>
</classpath>
<jar ...>
...
<manifest>
<attribute name="Class-Path" value="${tmpClasspath}"/>
</manifest>
</jar>
But:
build.xml:1067: serverLibs doesn't denote a zipfileset or a fileset
Is there any way to make this work?

Answer 1

The lib nested element of war only accepts a fileset or a zipfileset. Other resource collections like union are not supported. You may have a few ways to convert it to a fileset. If the union needs to be kept to be used somewhere else, then you can create a path element from it and use the Ant-Contrib pathtofileset task to convert it to a fileset:
<union id="serverLibs">
<fileset refid="commonLibs1"/>
<fileset dir="${lib}">
<include name="qux.jar"/>
</fileset>
</union>
<path id="serverLibsPath">
<resources refid="serverLibs" />
</path>
<pathtofileset pathrefid="serverLibsPath" name="serverLibsFileset" dir="${lib}" />
<war ...>
<lib refid="serverLibsFileset"/>
...
</war>
Or you can skip Ant-Contrib and use mappedresources with the path created above (see this post for an example).
A simpler way (if the union is only used by the war task) is to remove the union and just specify the combination of filesets in multiple lib elements:
<war ...>
<lib refid="commonLibs1"/>
<lib dir="${lib}">
<include name="qux.jar"/>
</lib>
...
</war>