main class in fat jar fails when using static factory method, but works fine in IDE - static

Question

I have a small project that i'm using shadowJar to create a fatjar to run from command line..
the main class entry point gets ref to class in the project using static factory method like this
static void main (args){
MessageSystemClient mclient = MessagePlatformFactoryProducer.getFactory().getMessagePlatformInstance("WLS")
println "howdi "....
}
when i run the fat jar at the command line i get an error like so
PS D:\Intellij-projects\message-platform-client\build\libs> java -jar message-platform-client-1.0-SNAPSHOT.jar --send "hello" -r
Exception in thread "main" java.io.FileNotFoundException: file:\D:\Intellij-projects\message-platform-client\build\libs\message-platform-client-1.0-SNAPSHOT.jar!\ApplicationConfig.groovy (The filename, directory name, or volume label syntax is incorrect)
at java.io.FileInputStream.open0(Native Method)
at java.io.FileInputStream.open(Unknown Source)
at java.io.FileInputStream.<init>(Unknown Source)
at groovy.util.CharsetToolkit.<init>(CharsetToolkit.java:77)
at org.codehaus.groovy.runtime.ResourceGroovyMethods.newReader(ResourceGroovyMethods.java:1741)
at org.codehaus.groovy.runtime.ResourceGroovyMethods.getText(ResourceGroovyMethods.java:592)
at org.codehaus.groovy.runtime.dgm$1013.doMethodInvoke(Unknown Source)
at org.codehaus.groovy.reflection.GeneratedMetaMethod$Proxy.doMethodInvoke(GeneratedMetaMethod.java:83)
at org.codehaus.groovy.runtime.metaclass.MethodMetaProperty$GetBeanMethodMetaProperty.getProperty(MethodMetaProperty.java:76)
at org.codehaus.groovy.runtime.callsite.GetEffectivePojoPropertySite.getProperty(GetEffectivePojoPropertySite.java:63)
at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callGetProperty(AbstractCallSite.java:298)
at com.softwood.implementation.MessagePlatformFactory.getMessagePlatformInstance(MessagePlatformFactory.groovy:29)
at com.softwood.client.AbstractMessagePlatformFactory$getMessagePlatformInstance.call(Unknown Source)
at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:47)
at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:115)
at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:127)
at com.softwood.cli.Launcher.main(Launcher.groovy:40)
however if i comment out the static factory call - and regenerate then the fat jar runs ok and prints the howdi to the console.
if i uncomment the factory lookup again, and just run the Launcher class in the IDE the code works fine with no problems
so why is it failing as a fatjar, but works as ordinary project?. secondly assuming its something to do with fatjar zip approach - how do i overcome this ?
I had a earlier version of the project that just directly called static methods on project classes, and that works fine as a fatjar - so the problem is with the static factory behavior inside a fatjar .
i tried to load the classes using
Launcher.getClass().getClassLoader().loadClass ("<various factory classes etc>")
the classes would load ok - but the factory call itself still breaks as shown above in stack trace
Can any one help me over this problem please?

Answer 1

Found it - in my factory methods I was doing a call like this to load a configFile:
File configFile = new File(classLoader.getResource("ApplicationConfig.groovy")?.getFile())
However as per related link, this won't work in a fat jar as there's no full file system in the jar.
What you have to do is use line like:
InputStream configStream = classLoader.getResourceAsStream("ApplicationConfig.groovy")
as this will work in the jar, and test if stream is null (can't find your resource in the fatjar) or you get the stream itself which you can read the text from the file.
Took a while, but now back on I think.