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antjareclipse-neon

is there a way to make a jar with the Eclipse generated ant script?

To my surprise the build.xml file generated by Eclipse (Neon) for Java has no element containing an invocation of a jar task. As often is the case with code generation I think you have to use it and make no edits so that you can regenerate - or - avoid code generation completely. A comment in the generated file suggests it might be possible to avoid edits by extending the capabilities by importing.

<!-- WARNING: Eclipse auto-generated file.
              Any modifications will be overwritten.
              To include a user specific buildfile here, simply create one in the same
              directory with the processing instruction <?eclipse.ant.import?>
              as the first entry and export the buildfile again. -->

I thought I would be able to use the <?eclipse.ant.import?> element in an second file called export.xml. In ant scripting there is supposed to be one project per buildfile so now there is a second project with a dependency on a target in the first project.

Regenerating build.xml reveals that it contains an "import" as expected.

<import file="export.xml"/>

Unfortunately this does not work. Running ant, which I do from the command line, just seems to result in the export/jar project being ignored.

The generated script with the import element (nested on the 7th line)...

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<project basedir="." default="build" name="ohana1">
    <property environment="env"/>
    <property name="debuglevel" value="source,lines,vars"/>
    <property name="target" value="1.8"/>
    <property name="source" value="1.8"/>
    <import file="export.xml"/>
    <path id="ohana1.classpath">
        <pathelement location="bin"/>
        <pathelement location="../export/ohana1/commons-collections-3.2.1.jar"/>
    </path>
    <target name="init">
        <mkdir dir="bin"/>
        <copy includeemptydirs="false" todir="bin">
            <fileset dir="src">
                <exclude name="**/*.launch"/>
                <exclude name="**/*.java"/>
            </fileset>
        </copy>
    </target>
    <target name="clean">
        <delete dir="bin"/>
    </target>
    <target depends="clean" name="cleanall"/>
    <target depends="build-subprojects,build-project" name="build"/>
    <target name="build-subprojects"/>
    <target depends="init" name="build-project">
        <echo message="${ant.project.name}: ${ant.file}"/>
        <javac debug="true" debuglevel="${debuglevel}" destdir="bin" includeantruntime="false" source="${source}" target="${target}">
            <src path="src"/>
            <classpath refid="ohana1.classpath"/>
        </javac>
    </target>
    <target description="Build all projects which reference this project. Useful to propagate changes." name="build-refprojects"/>
    <target description="copy Eclipse compiler jars to ant lib directory" name="init-eclipse-compiler">
        <copy todir="${ant.library.dir}">
            <fileset dir="${ECLIPSE_HOME}/plugins" includes="org.eclipse.jdt.core_*.jar"/>
        </copy>
        <unzip dest="${ant.library.dir}">
            <patternset includes="jdtCompilerAdapter.jar"/>
            <fileset dir="${ECLIPSE_HOME}/plugins" includes="org.eclipse.jdt.core_*.jar"/>
        </unzip>
    </target>
    <target description="compile project with Eclipse compiler" name="build-eclipse-compiler">
        <property name="build.compiler" value="org.eclipse.jdt.core.JDTCompilerAdapter"/>
        <antcall target="build"/>
    </target>
</project>

The export.xml file meant to make a jar...

<?eclipse.ant.import?>
<project basedir="." default="export" name="ohana1Export">
    <target depends="build,make-jar" name="export"/>
    <target name="make-jar">
        <jar destfile="../export/ohana1/${ant.project.name}.jar" basedir="bin"/>
    </target>
</project>

Note that the Eclipse Ant editor complains about this export.xml file because the target named build, which is a dependency, does not exist in this project/buildfile. The build target is in the generated build.xml. That error might be coming from a "dumb" editor so I went ahead to do a run of ant. Invoking ant from the command line I find that there is no jar file made.

Should I conclude that Eclipse's ant script generator is useless if you need to export a .jar file and that a human should maintain the ant script that meets all the requirements?

Solution

  • Yes, in my opinion the exported build.xml is useless, as of Eclipse Neon, if the intention is to make a .jar.

    Specifically do the following.

    • Manually write the trivial ant script that exports a .jar. The link at the bottom of this post has verbatim text on what the script might look like. You can use the built-in Xml Editor via New > Other > XML > XML File to create this new file which might be called makeJar.xml and save it. If the icon shown in the Package Explorer is still a plain XML file icon refreshing the project may change the icon to an Ant file icon. In the future, you can use Open With to get the Ant Editor instead of the XML Editor. This script will replace the manual exporting of a .jar that the user would otherwise perform via Eclipse.
    • This script can be added to Project > Properties > Builders. It would be placed second in the list of Builders. First in the list of Builders is the Java Builder which should already exist. When an Eclipse build is invoked the entire list of Builders will be processed in the order shown in the list of Builders. Thus not only will .class files be generated but also the .jar.

    What is achieved is greater automation since the .class generation and .jar generation are now integrated, which arguably was the point of using the exported build.xml in a failed attempt to generate the .jar.

    Here is the dialog at Project > Properties > Builders that you can use to create a new Builder. Select New then select Ant Builder. I gave the name makeJar to the new Builder.

    Builders

    Here is the dialog for the new Ant Builder that will allow you to browse to your buildfile which is your manually written Ant script that creates a .jar file. In this example the script is makeJar.xml. It also allows you to browse to the base directory to be used when the script is run.

    Configuration of the new Ant Builder

    After setting up the new Builder, a project "clean" or project "build" will create .class files and also the .jar.

    Eclipse's documentation on this subject is at the link. Note that it seems impossible to link the exact page that contains the instructions so you have to browse down the documentation tree to the section about "Ant buildfiles as project builders".

    Link to Eclipse and Ant