ResourceBuilder.java

package org.xenei.jdbc4sparql.impl.rdf;

import org.xenei.jdbc4sparql.iface.NamespacedObject;
import org.xenei.jena.entities.EntityManager;
import org.xenei.jena.entities.EntityManagerFactory;
import org.xenei.jena.entities.annotations.Subject;

import com.hp.hpl.jena.rdf.model.Model;
import com.hp.hpl.jena.rdf.model.Property;
import com.hp.hpl.jena.rdf.model.Resource;
import com.hp.hpl.jena.vocabulary.RDF;

public class ResourceBuilder {
	public static String getFQName(final Class<?> nsClass) {
		final String s = ResourceBuilder.getNamespace(nsClass);

		return s.substring(0, s.length() - 1);
	}

	public static String getNamespace(final Class<?> nsClass) {
		final EntityManager em = EntityManagerFactory.getEntityManager();
		final Subject subject = em.getSubject(nsClass);
		if (subject == null) {
			throw new IllegalArgumentException(String.format(
					"%s is does not have a subject annotation", nsClass));
		}
		return subject.namespace();
	}

	private final Model model;

	public ResourceBuilder(final Model model) {
		if (model == null) {
			throw new IllegalArgumentException("Model may not be null");
		}
		this.model = model;
	}

	public Property getProperty(final Class<?> typeClass, final String localName) {
		return model.createProperty(ResourceBuilder.getNamespace(typeClass),
				localName);
	}

	/**
	 * Get the resource from the model or create if if it does not exist.
	 *
	 * @return
	 */
	public Resource getResource(final String fqName, final Class<?> typeClass) {
		final Resource type = model.createResource(ResourceBuilder
				.getFQName(typeClass));

		Resource retval;
		if (hasResource(fqName)) {
			retval = model.getResource(fqName);
			if (!retval.hasProperty(RDF.type, type)) {
				throw new IllegalStateException(String.format(
						"Object %s is of type %s not %s", retval.getURI(),
						retval.getRequiredProperty(RDF.type).getResource()
						.getURI(), type.getURI()));
			}
		}
		else {
			retval = model.createResource(fqName, type);
		}
		return retval;
	}

	/**
	 * Determine if the resource is in the model.
	 *
	 * @param obj
	 * @return
	 */
	public boolean hasResource(final NamespacedObject obj) {
		return hasResource(obj.getFQName());
	}

	public boolean hasResource(final String fqName) {
		return model.contains(model.createResource(fqName), null);
	}
}