public Object getObjectInstance(Object obj,
    Name name,
    Context nameCtx,
    Hashtable environment) throws Exception 
{
        
        if (obj instanceof ResourceEnvRef) {
            Reference ref = (Reference) obj;
            ObjectFactory factory = null;
            RefAddr factoryRefAddr = ref.get(Constants.FACTORY);
            if (factoryRefAddr != null) {
                // Using the specified factory
                String factoryClassName = 
                    factoryRefAddr.getContent().toString();
                // Loading factory
                ClassLoader tcl = 
                    Thread.currentThread().getContextClassLoader();
                Class factoryClass = null;
                if (tcl != null) {
                    try {
                        factoryClass = tcl.loadClass(factoryClassName);
                    } catch(ClassNotFoundException e) {
                        NamingException ex = new NamingException
                            ("Could not load resource factory class");
                        ex.initCause(e);
                        throw ex;
                    }
                } else {
                    try {
                        factoryClass = Class.forName(factoryClassName);
                    } catch(ClassNotFoundException e) {
                        NamingException ex = new NamingException
                            ("Could not load resource factory class");
                        ex.initCause(e);
                        throw ex;
                    }
                }
                if (factoryClass != null) {
                    try {
                        factory = (ObjectFactory) factoryClass.newInstance();
                    } catch(Throwable t) {
                        if (t instanceof NamingException)
                            throw (NamingException) t;
                        NamingException ex = new NamingException
                            ("Could not create resource factory instance");
                        ex.initCause(t);
                        throw ex;
                    }
                }
            }
            // Note: No defaults here
            if (factory != null) {
                return factory.getObjectInstance
                    (obj, name, nameCtx, environment);
            } else {
                throw new NamingException
                    ("Cannot create resource instance");
            }
        }
        return null;
}

Crete a new Resource env instance.