MeBigFatGuy MeBigFatGuy - 1 month ago 9
Java Question

Custom ant task exposed thru antlib.xml

I have a jar with an ant task in it. My com/mebigfatguy/stringliterals/antlib.xml is

<antlib xmlns:stringliterals="ant:com.mebigfatguy.stringliterals">
<taskdef name="stringliterals" classname="com.mebigfatguy.stringliterals.StringLiteralsTask"/>
</antlib>


running jar tf stringliterals.jar i get

META-INF/
META-INF/MANIFEST.MF
com/
com/mebigfatguy/
com/mebigfatguy/stringliterals/
com/mebigfatguy/stringliterals/antlib.xml
com/mebigfatguy/stringliterals/SLClassVisitor.class
com/mebigfatguy/stringliterals/StringLiteralsTask.class
com/mebigfatguy/stringliterals/SLMethodVisitor.class
com/mebigfatguy/stringliterals/Literal.class
META-INF/maven/
META-INF/maven/com.mebigfatguy.stringliterals/
META-INF/maven/com.mebigfatguy.stringliterals/stringliterals/
META-INF/maven/com.mebigfatguy.stringliterals/stringliterals/pom.xml
META-INF/maven/com.mebigfatguy.stringliterals/stringliterals/pom.properties
com/mebigfatguy/org/
com/mebigfatguy/org/objectweb/
com/mebigfatguy/org/objectweb/asm/
com/mebigfatguy/org/objectweb/asm/AnnotationVisitor.class
com/mebigfatguy/org/objectweb/asm/AnnotationWriter.class
com/mebigfatguy/org/objectweb/asm/Attribute.class
com/mebigfatguy/org/objectweb/asm/ByteVector.class
com/mebigfatguy/org/objectweb/asm/ClassReader.class
com/mebigfatguy/org/objectweb/asm/ClassVisitor.class
com/mebigfatguy/org/objectweb/asm/ClassWriter.class
com/mebigfatguy/org/objectweb/asm/Context.class
com/mebigfatguy/org/objectweb/asm/Edge.class
com/mebigfatguy/org/objectweb/asm/FieldVisitor.class
com/mebigfatguy/org/objectweb/asm/FieldWriter.class
com/mebigfatguy/org/objectweb/asm/Frame.class
com/mebigfatguy/org/objectweb/asm/Handle.class
com/mebigfatguy/org/objectweb/asm/Handler.class
com/mebigfatguy/org/objectweb/asm/Item.class
com/mebigfatguy/org/objectweb/asm/Label.class
com/mebigfatguy/org/objectweb/asm/MethodVisitor.class
com/mebigfatguy/org/objectweb/asm/MethodWriter.class
com/mebigfatguy/org/objectweb/asm/Opcodes.class
com/mebigfatguy/org/objectweb/asm/Type.class
com/mebigfatguy/org/objectweb/asm/TypePath.class
com/mebigfatguy/org/objectweb/asm/TypeReference.class
com/mebigfatguy/org/objectweb/asm/signature/
com/mebigfatguy/org/objectweb/asm/signature/SignatureReader.class
com/mebigfatguy/org/objectweb/asm/signature/SignatureVisitor.class
com/mebigfatguy/org/objectweb/asm/signature/SignatureWriter.class


as you can see the task class is there

I put the jar in ~/.ant/lib, and When i try to run a task that references it like this:

<target name="literals" xmlns:stringliterals="antlib:com.mebigfatguy.stringliterals" description="generate report of string literals used in code">
<stringliterals:stringliterals>
<classpath refid="fb-contrib.classpath"/>
</stringliterals:stringliterals>
</target>


I get

literals:


parsing buildfile jar:file:/home/dave/.ant/lib/stringliterals-0.2.0.jar!/com/mebigfatguy/stringliterals/antlib.xml with URI = jar:file:/home/dave/.ant/lib/stringliterals-0.2.0.jar!/com/mebigfatguy/stringliterals/antlib.xml from a zip file
Finding class com.mebigfatguy.stringliterals.StringLiteralsTask

BUILD FAILED
/home/dave/dev/fb-contrib/build.xml:245: The following error occurred while executing this line:
jar:file:/home/dave/.ant/lib/stringliterals-0.2.0.jar!/com/mebigfatguy/stringliterals/antlib.xml:2: taskdef class com.mebigfatguy.stringliterals.StringLiteralsTask cannot be found
using the classloader AntClassLoader[]
at org.apache.tools.ant.taskdefs.Definer.addDefinition(Definer.java:607)
at org.apache.tools.ant.taskdefs.Definer.execute(Definer.java:237)
at org.apache.tools.ant.taskdefs.Antlib.execute(Antlib.java:177)
at org.apache.tools.ant.taskdefs.Definer.loadAntlib(Definer.java:428)
at org.apache.tools.ant.taskdefs.Definer.execute(Definer.java:277)
at org.apache.tools.ant.ComponentHelper.checkNamespace(ComponentHelper.java:874)
at org.apache.tools.ant.ComponentHelper.getDefinition(ComponentHelper.java:307)
at org.apache.tools.ant.ComponentHelper.createComponent(ComponentHelper.java:284)
at org.apache.tools.ant.ComponentHelper.createComponent(ComponentHelper.java:263)
at org.apache.tools.ant.UnknownElement.makeObject(UnknownElement.java:429)
at org.apache.tools.ant.UnknownElement.maybeConfigure(UnknownElement.java:163)
at org.apache.tools.ant.Task.perform(Task.java:347)
at org.apache.tools.ant.Target.execute(Target.java:435)
at org.apache.tools.ant.Target.performTasks(Target.java:456)
at org.apache.tools.ant.Project.executeSortedTargets(Project.java:1393)
at org.apache.tools.ant.Project.executeTarget(Project.java:1364)
at org.apache.tools.ant.helper.DefaultExecutor.executeTargets(DefaultExecutor.java:41)
at org.apache.tools.ant.Project.executeTargets(Project.java:1248)
at org.apache.tools.ant.Main.runBuild(Main.java:851)
at org.apache.tools.ant.Main.startAnt(Main.java:235)
at org.apache.tools.ant.launch.Launcher.run(Launcher.java:280)
at org.apache.tools.ant.launch.Launcher.main(Launcher.java:109)
Caused by: java.lang.ClassNotFoundException: com.mebigfatguy.stringliterals.StringLiteralsTask
at org.apache.tools.ant.AntClassLoader.findClassInComponents(AntClassLoader.java:1366)
at org.apache.tools.ant.AntClassLoader.findClass(AntClassLoader.java:1315)
at org.apache.tools.ant.AntClassLoader.loadClass(AntClassLoader.java:1068)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:348)
at org.apache.tools.ant.taskdefs.Definer.addDefinition(Definer.java:579)
... 21 more


I've done this several times before with no issues, this time however i don't see where i've gone wrong. Any way to debug this classloader issue?

GitHub project here https://github.com/mebigfatguy/stringliterals

Answer

The problem turned out to be a badly formatted manifest file. sorry!