Hibernate example source code file (PojoInstantiator.java)

This example Hibernate source code file (PojoInstantiator.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Hibernate tags/keywords

class, constructor, coremessagelogger, could, instantiationexception, instantiationexception, io, ioexception, no, object, object, pojoinstantiator, pojoinstantiator, propertynotfoundexception, propertynotfoundexception, reflection

The Hibernate PojoInstantiator.java source code

/*
 * Hibernate, Relational Persistence for Idiomatic Java
 *
 * Copyright (c) 2008, Red Hat Middleware LLC or third-party contributors as
 * indicated by the @author tags or express copyright attribution
 * statements applied by the authors.  All third-party contributions are
 * distributed under license by Red Hat Middleware LLC.
 *
 * This copyrighted material is made available to anyone wishing to use, modify,
 * copy, or redistribute it subject to the terms and conditions of the GNU
 * Lesser General Public License, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License
 * for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this distribution; if not, write to:
 * Free Software Foundation, Inc.
 * 51 Franklin Street, Fifth Floor
 * Boston, MA  02110-1301  USA
 *
 */
package org.hibernate.tuple;

import java.io.IOException;
import java.io.Serializable;
import java.lang.reflect.Constructor;
import org.hibernate.internal.CoreMessageLogger;
import org.hibernate.InstantiationException;
import org.hibernate.PropertyNotFoundException;
import org.hibernate.bytecode.spi.ReflectionOptimizer;
import org.hibernate.internal.util.ReflectHelper;
import org.hibernate.mapping.Component;
import org.hibernate.mapping.PersistentClass;
import org.hibernate.metamodel.binding.EntityBinding;

import org.jboss.logging.Logger;

/**
 * Defines a POJO-based instantiator for use from the tuplizers.
 */
public class PojoInstantiator implements Instantiator, Serializable {

    private static final CoreMessageLogger LOG = Logger.getMessageLogger(CoreMessageLogger.class, PojoInstantiator.class.getName());

	private transient Constructor constructor;

	private final Class mappedClass;
	private final transient ReflectionOptimizer.InstantiationOptimizer optimizer;
	private final boolean embeddedIdentifier;
	private final Class proxyInterface;

	public PojoInstantiator(Component component, ReflectionOptimizer.InstantiationOptimizer optimizer) {
		this.mappedClass = component.getComponentClass();
		this.optimizer = optimizer;

		this.proxyInterface = null;
		this.embeddedIdentifier = false;

		try {
			constructor = ReflectHelper.getDefaultConstructor(mappedClass);
		}
		catch ( PropertyNotFoundException pnfe ) {
            LOG.noDefaultConstructor(mappedClass.getName());
			constructor = null;
		}
	}

	public PojoInstantiator(PersistentClass persistentClass, ReflectionOptimizer.InstantiationOptimizer optimizer) {
		this.mappedClass = persistentClass.getMappedClass();
		this.proxyInterface = persistentClass.getProxyInterface();
		this.embeddedIdentifier = persistentClass.hasEmbeddedIdentifier();
		this.optimizer = optimizer;

		try {
			constructor = ReflectHelper.getDefaultConstructor( mappedClass );
		}
		catch ( PropertyNotFoundException pnfe ) {
            LOG.noDefaultConstructor(mappedClass.getName());
			constructor = null;
		}
	}

	public PojoInstantiator(EntityBinding entityBinding, ReflectionOptimizer.InstantiationOptimizer optimizer) {
		this.mappedClass = entityBinding.getEntity().getClassReference();
		this.proxyInterface = entityBinding.getProxyInterfaceType().getValue();
		this.embeddedIdentifier = entityBinding.getHierarchyDetails().getEntityIdentifier().isEmbedded();
		this.optimizer = optimizer;

		try {
			constructor = ReflectHelper.getDefaultConstructor( mappedClass );
		}
		catch ( PropertyNotFoundException pnfe ) {
			LOG.noDefaultConstructor(mappedClass.getName());
			constructor = null;
		}
	}

	private void readObject(java.io.ObjectInputStream stream)
	throws ClassNotFoundException, IOException {
		stream.defaultReadObject();
		constructor = ReflectHelper.getDefaultConstructor( mappedClass );
	}

	public Object instantiate() {
		if ( ReflectHelper.isAbstractClass(mappedClass) ) {
			throw new InstantiationException( "Cannot instantiate abstract class or interface: ", mappedClass );
		}
		else if ( optimizer != null ) {
			return optimizer.newInstance();
		}
		else if ( constructor == null ) {
			throw new InstantiationException( "No default constructor for entity: ", mappedClass );
		}
		else {
			try {
				return constructor.newInstance( (Object[]) null );
			}
			catch ( Exception e ) {
				throw new InstantiationException( "Could not instantiate entity: ", mappedClass, e );
			}
		}
	}

	public Object instantiate(Serializable id) {
		final boolean useEmbeddedIdentifierInstanceAsEntity = embeddedIdentifier &&
				id != null &&
				id.getClass().equals(mappedClass);
		return useEmbeddedIdentifierInstanceAsEntity ? id : instantiate();
	}

	public boolean isInstance(Object object) {
		return mappedClass.isInstance(object) ||
				( proxyInterface!=null && proxyInterface.isInstance(object) ); //this one needed only for guessEntityMode()
	}
}