Ant cannot find a class needed by an externally defined taskdef

Question

I am trying to use the axis-java2wsdl ant task to create a wsdl from one of my java classes, but I cannot get the classpath correct.

I am using Ubuntu's libaxis-java package which installs axis-ant.jar in $ANT_HOME/lib and axis.jar in /usr/share/java. The interesting parts of my build.xml look like this:

<property name="library.dir" value="lib"/>
<property name="system.library.dir" value="/usr/share/java"/>
<path id="libraries">
    <fileset dir="${library.dir}">
     <include name="*.jar"/>
    </fileset>
    <fileset dir="${system.library.dir}">
     <include name="*.jar"/>
    </fileset>
</path>

<target name="genwsdl" depends="compile">
    <taskdef resource="axis-tasks.properties" classpathref="libraries"/>
    <axis-java2wsdl>
            details omitted
    </axis-java2wsdl>
</target>

Running ant genwsdl results in:

/build.xml:50: taskdef A class needed by class
org.apache.axis.tools.ant.wsdl.Wsdl2javaAntTask
cannot be found: org/apache/axis/utils/DefaultAuthenticator

Ant is able to find the definition of the axis-java2wsdl task, because axis-ant.jar is in $ANT_HOME/lib, but it cannot find classes in axis.jar, even though that jar is on the path defined by "libraries"

I know it's a classpath issue because I was able to get past DefaultAuthenticator to other class's not found by symlinking axis.jar into $ANT_HOME/lib. How can I get the taskdef to recognize jar files in /usr/share/lib or my project's local lib directory without symlinking everything into $ANT_HOME/lib?

EDIT:

I was finally able to successfully generate the wsdl with this line:

ant -lib /usr/share/java/axis.jar -lib /usr/share/java/jaxrpc.jar -lib /usr/share/java/wsdl4j.jar -lib /usr/share/java/commons-logging.jar -lib /usr/share/java/commons-discovery.jar -lib build genwsdl

I would still very much appreciate if somebody could tell me what I'm doing wrong in not being able to define those libraries in build.xml

Answer 1

Ant mechanism for adding libraries is:

• via command line argument -lib
• adding to ${user.home}/.ant/lib
• adding to ${ant.home}/lib

Only. The manual doesn't mention anything about using the system.library.dir property. Probably it pretty much ignored for this purpose.

Also, run ant in verbose mode ( and -verbose ) to see what is doing under the hood.

Answer 2

In general, this works. But you need to check very carefully which classes are where.

If your task class can be loaded in a classloader higher up in the classloader hierarchy (like CLASSPATH or ANT_HOME/lib) then your classpathref will simply get ignored.

Read the FAQ entry for more details.

Ant's class loader implementation uses Java's delegation model

The ClassLoader class uses a delegation model to search for classes and resources. Each instance of ClassLoader has an associated parent class loader. When called upon to find a class or resource, a ClassLoader instance will delegate the search for the class or resource to its parent class loader before attempting to find the class or resource itself. The virtual machine's built-in class loader, called the bootstrap class loader, does not itself have a parent but may serve as the parent of a ClassLoader instance.

Note: running ant -diagnostics can help too.

Answer 3

Why not just take the simplest option and specify the classpath in your <taskdef>?

<taskdef resource="axis-tasks.properties">
    <classpath>
        <fileset file="/path/to/axis/jars"/>
    </classpath>
</taskdef>

Or create a second <classpath> entry that subsets library.dir?

<path id="axis-tools-classpath">
    <fileset dir="/path/to/axis/home">
        <include name="*.jar"/>
    </fileset>
    <path refid="library.dir"/>
</path>

Messing around with ${ant.home}/lib is not such a good idea and can almost always be avoided.

Answer 4

It works for me to specify the classpath directly in the taskdef task, as menstioned by matt b. For my project I find it useful to include the taskdef library in the project folder and specify the classpath in the ant build file, to simply setup on other development pcs. I use the following taskdef:

<taskdef resource="antenna.properties" classpath="${myprojectroot}/lib/antenna-bin-1.2.1-beta.jar"/>

Note that this might not work for versions of ant earlier than 1.7.0.