Some Groovy Class-Loading Notes

Was trying to load a resource (*.properties) from the class-path and as you know, class loading can be a PITA at different enviroments (IDEs, build tools, tests, containers).

Here's the snippet I used, ran with Maven and Eclipse IDE, target/test-classes is in the class-path.

String name = "aflexi.itest.properties"

// System CL
println ClassLoader.getSystemClassLoader()
// Uses system or bootstrap CL
println ClassLoader.getSystemResource(name)

// Caller CL
println ClassLoader.getCallerClassLoader()
println ClassLoader.getCallerClassLoader().getResource(name)

// Class's class loader. Perfectly fine in both places
println getClass().getClassLoader()
println getClass().getClassLoader().getResource("aflexi.itest.properties")

// Doesn't work anywhere, the CL is the one of previous, but the name will be resolved as "net/aflexi/cdn/test/itest/aflexi.itest.properties"
println getClass().getClassLoader0()
println getClass().getResource("aflexi.itest.properties")

// Doesn't work either. Using Groovy's calling class.
println ReflectionUtils.getCallingClass()
println ReflectionUtils.getCallingClass().getResource("aflexi.itest.properties")

And here's the result:

Expression / Class Loader	Test 1: Instance	Test 2: Instance	Test 1: Found Resource?	Test 2: Found Resource?
ClassLoader.getSystemClassLoader().getResource()	sun.misc.Launcher$AppClassLoader@19134f4	sun.misc.Launcher$AppClassLoader@19134f4	1	0
ClassLoader.getCallerClassLoader().getResource()	sun.misc.Launcher$AppClassLoader@19134f4	org.codehaus.groovy.tools.RootLoader@8965fb	1	1
getClass().getClassLoader().getResource()	groovy.lang.GroovyClassLoader$InnerLoader@14177f3	groovy.lang.GroovyClassLoader$InnerLoader@dc0435	1	1
getClass().getResource()	groovy.lang.GroovyClassLoader$InnerLoader@14177f3	groovy.lang.GroovyClassLoader$InnerLoader@dc0435	0	0
ReflectionUtils.getCallingClass().getResource()	class cuke4duke.internal.groovy.GroovyLanguage	class groovy.ui.GroovyMain	0	0

Take note that, getClass().getResource() uses the same CL instance (otherwise system CL) with getClass().getClassLoader().getResource(). The reason why it failed is that, it resolves the name of the properties file with package name, i.e. aflexi.itest.properties to net/aflexi/cdn/test/itest/aflexi.itest.properties.