Why cannot Ant taskdef cannot load a resource outside ./net

When declaring external ant tasks using taskdef, for instance ant-contrib, the proposed setup is to use the followin taskdef:

<taskdef resource="net/sf/antcontrib/antcontrib.properties">
  <classpath>
    <pathelement location="lib/ant-contrib/ant-contrib-1.0b3.jar"/>
  </classpath&开发者_如何学Pythongt;
</taskdef>

This works when antcontrib.properties is located in net/sf/antcontrib relative to the build.xml file.

But when I put it in lib/net/sf/antcontrib and changes the taskdef into

<taskdef resource="lib/net/sf/antcontrib/antcontrib.properties">
  <classpath>
    <pathelement location="lib/ant-contrib/ant-contrib-1.0b3.jar"/>
  </classpath>
</taskdef>

Ant is not able to find the properties file, it gives the error

[taskdef] Could not load definitions from resource
lib/net/sf/antcontrib/antcontrib.properties. It could not be found.

It seems like ant treats the lib directory separately and fails to load a taskdef resource from there.

As Alex said, you shouldn't need to unzip the jar. The <taskdef> can load antcontrib.properties directly out of the jar.

The error you got is because you changed the resource path, but the path to the file inside the compressed jar/zip is still the same. The taskdef isn't paying attention to the properties file you moved because the <classpath> you provided to <taskdef> tells it to only look in the jar.

Use antlib.xml resource:

Here is the taskdef definition that I use:

<property name="ant-contrib.jar" location="..."/>

<taskdef
  resource="net/sf/antcontrib/antlib.xml"
  uri="http://ant-contrib.sourceforge.net"
>
  <classpath>
    <pathelement location="${ant-contrib.jar}"/>
  </classpath>
</taskdef>

You do not need to extract anything from the jar file. Also, uri attribute is optional if you do not want to use namespaces with antcontrib tasks.

To handle classpath for tasks definitions, I use a classpath ref in Ant, it's way easier. You can link either a directory containing classes, either a directory containing many .jar, either (of course) a single .jar.

For example :

    <!-- Properties -->
    <property name="lib" value="lib/" />
    <property name="classes" value="bin/" />

    <!-- Classpath definition -->
    <path id="runtime-classpath" >
        <pathelement location="${bin}" />
        <fileset dir="${lib}">
            <include name="*.jar"/>
        </fileset>
    </path>

    <!-- Taskdefs definitions -->
    <taskdef name="myTask" classname="org.stackoverflow.tasks.MyTask" classpathref="runtime-classpath" />

    <!-- Tasks -->
    <target name="test" description="Test Action">
            <myTask parameter1="value" />
    </target>