Creating a runnable jar. Various problems

ant, jar, java

Solution

I know responding to your question can be frowned upon, but I did manage to solve this problem yesterday. Of all the options I tried I found the fastest solution was to replicate the Eclipse Runnable Jar Export Wizard. It requires the `jar-in-jar-loader.zip` which can be acquired using the Runnable Jar Export Wizard... or you can find it via Google/Eclipse install.

I found this solution was fast to build (30s) and much faster to run (5s bootup cost). It also left the jar structure very neat with no exploded jars.

<target name="compile" depends="resolve">
    <mkdir dir="bin"/>
    <!-- Copy all non java resources since jar javac will exclude them by default. Needed for xmls, properties etc --->
    <copy todir="bin">
        <fileset dir="src" excludes="**/*.java" />
    </copy>

    <javac srcdir="src" destdir="bin" debug="true" deprecation="on">
        <classpath>
            <path refid="ivy.path" />
        </classpath>
    </javac>
</target>


<!-- Creates the runnable jar. Copies the dependencies as jar files, into the top level of a new jar. 
     This means nothing without a custom classloader and manifest with a jar listing -->
<target name="jar" depends="compile" description="Create one big jarfile.">

    <path id="dependencies.path">
        <fileset dir="lib">
            <include name="**/*.jar" />
        </fileset>
    </path>

    <pathconvert property="manifest.classpath" pathsep=" ">
        <path refid="dependencies.path" />
        <mapper>
            <chainedmapper>
                <flattenmapper />
                <globmapper from="*.jar" to="*.jar" />
            </chainedmapper>
        </mapper>
    </pathconvert>

    <mkdir dir="${dist}"/>
    <jar destfile="${dist}/jar/Runnable.jar" filesetmanifest="mergewithoutmain">
        <manifest>
            <attribute name="Main-Class" value="org.eclipse.jdt.internal.jarinjarloader.JarRsrcLoader" />
            <attribute name="Rsrc-Main-Class" value="mymainclass" />
            <attribute name="Class-Path" value="." />
            <attribute name="Rsrc-Class-Path" value="./ ${manifest.classpath}" />
        </manifest>
        <fileset dir="bin" />
        <zipfileset src="jar-in-jar-loader.zip" />
        <zipfileset dir="lib" includes="**/*.jar*" />
    </jar>
</target>

Problem

I've been working on a command line executable Java program. It's in the testing phase, and packaging it up has proved a bit of an issue. The crux of this problem revolves around the MANY dependencies my application has. My lib folder (containing jars) is close on 500mb. At the moment I have been using the Eclipse Runnable Jar Export wizard. Works flawlessly, except it has to be done from Eclipse. It generates a Jar about 500mb in size (don't ask... suffice to say there need to be a lot of COBOL programs being packaged inside this program). This process takes <30s. Ideally I would like this to be an Ant task of some kind, runnable via Jenkins and published to a repository. That way a user can just grab a Jar and run it. Options I have investigated: Custom classloader (FatJar, OneJar etc). - Works - Slow to execute at runtime as it's required to unpack the jar. - File structure is basically a Jar full of jars and the main class is delegated through the custom classloader. Fast build time (5 mins) ``` <target name="hello" depends="compile"> <property name="classes.dir" value="onejar" /> <property name="build.dir" value="bin" /> <one-jar destfile="hello.jar"> <manifest> <attribute name="One-Jar-Main-Class" value="mainclass" /> <attribute name="Class-Path" value="." /> <attribute name="One-Jar-Show-Expand" value="true" /> </manifest> <main> <fileset dir="${build.dir}"/> </main> <lib> <fileset dir="lib"> <include name="**/*.jar"/> </fileset> </lib> </one-jar> </target> ``` Manually collecting dependencies, unpacking them into a folder, then jarring them all up with a custom MANIFEST file. - Can't get it to work - LARGE (1500mb+) Slow build time (20min +) ``` <target name="compile" depends="resolve"> <javac srcdir="src" destdir="bin" debug="true" deprecation="on"> <classpath> <path refid="ivy.path" /> </classpath> </javac> </target> <target name="jar" depends="compile" description="Create one big jarfile."> <jar jarfile="${dist}/deps.jar"> <zipgroupfileset dir="lib"> <include name="**/*.jar" /> </zipgroupfileset> </jar> <sleep seconds="1" /> <jar jarfile="${dist}/myjar.jar" basedir="bin"> <zipfileset src="${dist}/deps.jar" excludes="META-INF/*.SF" /> <manifest> <attribute name="Main-Class" value="mymainclassishere" /> </manifest> </jar> </target> ``` So yeah, does anyone have any suggestions? I am interested to hear peoples thoughts. Edit: Specifically.... WHY the Eclipse Runnable Jar Export Wizard can export my Jar in less then 30s, yet my build times are > 30 minutes.

Original source