Sunday, December 13, 2009

Packaging Scala applets into one jar in NetBeans with JarJar [Updated]

Pretty much a note to self; using NetBeans that started off as 6.7.1, but has the bleeding-edge depot, and using a Scala 2.8 nightly, FWIW.

Get the jarjar tool; put it and a copy of scala-library.jar and scala-swing.jar in a lib directory under the project. Create a build.xml post-jar target to read

    <target name="-post-jar">
      <taskdef name="jarjar" classname="com.tonicsystems.jarjar.JarJarTask"
               classpath="lib/jarjar-1.0.jar"/>
      <jarjar jarfile="${dist.jar}">
        <fileset dir="${build.classes.dir}"/>
        <zipgroupfileset dir="lib" includes="scala-*.jar" />
        <keep pattern="[your.root.package].*"/>
      </jarjar>
    </target>

Clean and build, get a lot of Scala classes in your output jar file. For which there is then pack200 support to crunch further.

There is an Ant task for that, which we can add to the post-jar target in build.xml thus

    <target name="-post-jar">
      <taskdef name="jarjar" classname="com.tonicsystems.jarjar.JarJarTask"
               classpath="lib/jarjar-1.0.jar"/>
      <taskdef name="pack200"
               classname="com.sun.tools.apache.ant.pack200.Pack200Task"
               classpath="lib/Pack200Task.jar"/>
      <jarjar jarfile="${dist.jar}">
        <fileset dir="${build.classes.dir}"/>
        <zipgroupfileset dir="lib" includes="scala-*.jar" />
        <keep pattern="[your.root.package].*"/>
      </jarjar>
      <pack200 src="${dist.jar}"
               destfile="${dist.jar}.pack.gz"
               GZIPOutput="yes"
               verbose="0"
               />
    </target>

which brings in my first test case, a 2.5Mb jar down to just under 900kb.

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