Run a Ruby script file from Java with JRuby's ScriptingContainer -- both "out of a JAR" and "inside a JAR"

build.gradle

buildscript {
    repositories {
        jcenter()
    }
    dependencies {
        classpath 'com.github.jengelman.gradle.plugins:shadow:1.2.3'
    }
}

repositories {
    mavenCentral()
}

apply plugin: 'java'
apply plugin: 'com.github.johnrengelman.shadow'

dependencies {
    compile 'org.jruby:jruby-complete:9.1.5.0'
    testCompile 'junit:junit:4.+'
}

sourceSets {
    main {
        java {
            srcDir '.'
            exclude 'Test*.java'
        }
        resources {
            srcDir '.'
            include '*.rb'
        }
    }
    test {
        java {
            srcDir '.'
            include 'Test*.java'
        }
    }
}

test {
    testLogging {
        events 'passed', 'skipped', 'failed', 'standardOut', 'standardError'
    }
}

shadowJar {
    manifest {
        attributes 'Main-Class': 'JRubyRunScript'
    }
}

task run(type: JavaExec) {
    main = project.hasProperty('main') ? project.getProperty('main') : 'JRubyRunScript'
    classpath = sourceSets.main.runtimeClasspath
    args 'main'
}

JRubyRunScript.java

import java.net.URL;
import java.net.URISyntaxException;
import org.jruby.embed.AttributeName;
import org.jruby.embed.LocalContextScope;
import org.jruby.embed.PathType;
import org.jruby.embed.ScriptingContainer;

/*
 * Out-of-jar:
 *     $ ./gradlew run
 *
 * In-jar:
 *     $ ./gradlew shadowJar
 *     $ java -jar build/libs/JRubyRunScript-all.jar
 */
public class JRubyRunScript {
    public static void main(final String[] args) {
        final ScriptingContainer jruby = new ScriptingContainer(LocalContextScope.SINGLETON);
        final String[] argsJRuby = { "foo", "bar", "baz", "qux" };
        jruby.setArgv(argsJRuby);

        final URL classUrl = JRubyRunScript.class.getResource("JRubyRunScript.class");

        if (classUrl.getProtocol().equals("jar")) {
            System.out.println("Running in a jar file.");

            // jruby.runScriptlet(PathType.ABSOLUTE, "file:/.../something.jar!/script.rb") does not work!
            // jruby.runScriptlet(PathType.ABSOLUTE, "uri:classloader/script.rb") does not work!
            jruby.runScriptlet(PathType.CLASSPATH, "script.rb");
        } else if (classUrl.getProtocol().equals("file")) {
            System.out.println("Running out of a jar file.");

            // "user.dir" (working directory) should be the same as "script.rb".
            jruby.setAttribute(AttributeName.BASE_DIR, System.getProperty("user.dir"));

            // jruby.setScriptFilename("script.rb") does not work!
            jruby.runScriptlet(PathType.RELATIVE, "script.rb");
        } else {
            System.out.println("Running at an unrecognized location!");
            System.exit(1);
        }
    }
}

script.rb

#!/usr/bin/env ruby
ARGV.each { |arg| puts "in-script: " + arg }

$ ./gradlew run
:compileJava
:processResources
:classes
:run
Running out of a jar file.
in-script: foo
in-script: bar
in-script: baz
in-script: qux

BUILD SUCCESSFUL

Total time: 3.762 secs

$ ./gradlew shadowJar
:compileJava
:processResources
:classes
:shadowJar

BUILD SUCCESSFUL

Total time: 3.415 secs

$ java -jar build/libs/JRubyRunScript-all.jar
Running in a jar file.
in-script: foo
in-script: bar
in-script: baz
in-script: qux