Embedder.java

import org.jruby.embed.PathType;
import org.jruby.embed.ScriptingContainer;

public class Embedder {
	public ScriptingContainer container;
	public String file;
	
    public Embedder(String filename) {
		file = filename;
        container = new ScriptingContainer();
        container.runScriptlet(PathType.CLASSPATH, file);
    }

	public RubyObject rubyClass(String classname) {
		Object obj = container.runScriptlet(classname);
		return new RubyObject(obj);
	}

	public RubyObject instantiate(String classname, Object[] args) {
		Object robj = rubyClass(classname).send("new", args, Object.class);
		return new RubyObject(robj);
	}
	
	public class RubyObject {
		private Object obj;
		
		public RubyObject(Object object) {
			obj = object;
		}
		
		public <T> T send(String methodName, Class<T> returnType) {
	        return container.callMethod(obj, methodName, returnType);
	    }
	
		public <T> T send(String methodName, Object singleArg, Class<T> returnType) {
	        return container.callMethod(obj, methodName, singleArg, returnType);
	    }
	
		public <T> T send(String methodName, Object[] args, Class<T> returnType) {
	        return container.callMethod(obj, methodName, args, returnType);
	    }
	}

    public static void main(String[] args) {
       	Embedder ruby = new Embedder("code.rb");

		Object[] call_args = {"foo", "bar"};
		RubyObject thingy = ruby.instantiate("SomeClass", call_args);
		System.out.println(thingy.send("bazbat", String.class));
    }
}