Ant: Source and target files are the same. How to detect a change?

Question

We are using JiBX. The important thing to know is that JiBX modifies the already compiled class files.

We do our compile:

<javac destdir="${main.destdir}">
    <src path="${main.srcdir}"/>
    <classpath refid="main.classpath"/>
</javac>

Then, we call JiBX:

<jibx load="true"
    binding="{$binding.file}">
    <classpath refid="main.classpath"/>
    <classpath refid="main.destdir.classpath"/>
</jibx>

This uses an XML file that updates the classfiles compiled by <javac> above. The problem is how do I know that the files have been compiled, but not processed by JiBX? I'd like to put some logic in my program, so that files are not updated twice by JiBX. Besides, it's bad form to duplicate work that already been done.

Patrice M. · Accepted Answer · 2012-10-19 05:13:31Z

2

After the jibx build step, generate a marker file, e.g.

<touch file="${target.dir}/jibx.marker" />

Only perform the jibx build step if that marker file is older than the .class files (indicating that the javac ran more recently than the last jibx).

For that bit of logic, you can use the traditional ant way:

<uptodate property="jibx.uptodate" targetfile="${target.dir}/jibx.marker">
   <srcfiles dir="${main.destdir}" includes="...../*.class" />
</uptodate>

And then use the property with an unless clause when invoking the jixb target.

Or, you can use Antcontrib's outofdate alternative:

<outofdate>
  <sourcefiles>
    <fileset dir="${main.destdir}" includes="...../*.class" />
</sourcefiles>
<targetfiles>
    <fileset dir="${target.dir}" includes="jibx.marker"/>
</targetfiles>
<sequential>
    <jibx load="true"
        binding="{$binding.file}">
        <classpath refid="main.classpath"/>
        <classpath refid="main.destdir.classpath"/>
    </jibx>
</sequential>
</outofdate>

answered Oct 19, 2012 at 5:13

Patrice M.

4,3392 gold badges29 silver badges39 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

David W. Over a year ago

I originally had the <javac> task generate the marker file, and it wasn't working. Yeah, now I see that JiBX has to do that. What if there is no marker file which will happen first time through? Will <outofdate> work or throw a temper tantrum because the source doesn't exist? Guess I'll have to give it a try. Worse comes to worse, I'll wrap the whole thing in a <if> statement.

David W. Over a year ago

Ach! Doesn't work! Jibx updates the classfiles. The classfiles and the monitor file have the same timestamp which makes JiBX remunge the classfiles. I think I need two monitor files: One when Javac is executed and one when JiBX is executed.

Community · Accepted Answer · 2017-05-23 12:27:56Z

I'm giving this to Patrice M. because his suggestion put me on the right track. However, it didn't quite work out as he stated. (Sorry, if I got he pronoun wrong, but Patrice can be both a male or female name.)

What I had to do was create two watch files: One for the Java compile, and one for the JiBX changes.

<!-- Check if Javac is out of date. If so, create javac watcher -->
<outofdate verbose="true">
    <sourcefiles>
        <fileset dir="${main.srcdir}">
            <include name="*.java"/>
        </fileset>
    </sourcefiles>
    <mapper type="regexp"
        from="${main.srcdir}/(.*)\.java"
        to="${main.destdir}/(\1).class"/>
    <sequential>
        <echo message="Java compiled"/>
        <echo message="Java compiled"
            file="${target.dir}/${javac.monitor.file}"/>
    </sequential>
</outofdate>

<javac destdir="${main.destdir}"
    debug="${javac.debug}">
    <src path="${main.srcdir}"/>
    <classpath refid="main.classpath"/>
</javac>

<!-- Compare javac and jibx monitoring file -->
<!-- If out of date, rerun jibx -->
<outofdate>
    <sourcefiles>
        <fileset dir="${target.dir}">
            <include name="${javac.monitor.file}"/>
        </fileset>
    </sourcefiles>
    <targetfiles>
        <fileset dir="${target.dir}">
            <include name="${jibx.monitor.file}"/>
        </fileset>
    </targetfiles>
    <sequential>
        <jibx load="true"
            binding="${target.dir}/binding-gg.xml">
            <classpath refid="main.classpath"/>
            <classpath refid="main.destdir.classpath"/>
        </jibx>

        <!-- Create JiBX monitoring file -->
        <echo message="Compiled and JiBX"
            file="${target.dir}/${jibx.monitor.file}"/>
    </sequential>
</outofdate>

I create the javac monitoring file if the source is out of date with the classes because that's when I compile. I have to create the JiBX outofdate monitoring file only when I run JiBX and that's inside the <outofdate> for JiBX.

I guess I could also put a source on the XML JiBX files too just to be sure.

Collectives™ on Stack Overflow

Ant: Source and target files are the same. How to detect a change?

2 Answers 2

2 Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

2 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related