entitytype.java

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//$Id: EntityType.java 10777 2006-11-08 22:02:28Z [e-mail] $
package org.hibernate.type;

import java.io.Serializable;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Map;

import org.dom4j.Element;
import org.dom4j.Node;
import org.hibernate.AssertionFailure;
import org.hibernate.EntityMode;
import org.hibernate.HibernateException;
import org.hibernate.MappingException;
import org.hibernate.engine.EntityUniqueKey;
import org.hibernate.engine.ForeignKeys;
import org.hibernate.engine.Mapping;
import org.hibernate.engine.PersistenceContext;
import org.hibernate.engine.SessionFactoryImplementor;
import org.hibernate.engine.SessionImplementor;
import org.hibernate.persister.entity.EntityPersister;
import org.hibernate.persister.entity.Joinable;
import org.hibernate.persister.entity.UniqueKeyLoadable;
import org.hibernate.proxy.HibernateProxy;
import org.hibernate.proxy.LazyInitializer;
import org.hibernate.tuple.ElementWrapper;
import org.hibernate.util.ReflectHelper;

/**
 * Base for types which map associations to persistent entities.
 *
 * @author Gavin King
 */
public abstract class EntityType extends AbstractType implements AssociationType {

	private final String associatedEntityName;
	protected final String uniqueKeyPropertyName;
	protected final boolean isEmbeddedInXML;
	private final boolean eager;
	private final boolean unwrapProxy;

	private transient Class returnedClass;

	/**
	 * Constructs the requested entity type mapping.
	 *
	 * @param entityName The name of the associated entity.
	 * @param uniqueKeyPropertyName The property-ref name, or null if we
	 * reference the PK of the associated entity.
	 * @param eager Is eager fetching enabled.
	 * @param isEmbeddedInXML Should values of this mapping be embedded in XML modes?
	 * @param unwrapProxy Is unwrapping of proxies allowed for this association; unwrapping
	 * says to return the "implementation target" of lazy prooxies; typically only possible
	 * with lazy="no-proxy".
	 */
	protected EntityType(
			String entityName,
			String uniqueKeyPropertyName,
			boolean eager,
			boolean isEmbeddedInXML,
			boolean unwrapProxy) {
		this.associatedEntityName = entityName;
		this.uniqueKeyPropertyName = uniqueKeyPropertyName;
		this.isEmbeddedInXML = isEmbeddedInXML;
		this.eager = eager;
		this.unwrapProxy = unwrapProxy;
	}

	/**
	 * An entity type is a type of association type
	 *
	 * @return True.
	 */
	public boolean isAssociationType() {
		return true;
	}

	/**
	 * Explicitly, an entity type is an entity type ;)
	 *
	 * @return True.
	 */
	public final boolean isEntityType() {
		return true;
	}

	/**
	 * {@inheritDoc}
	 */
	public boolean isMutable() {
		return false;
	}

	/**
	 * Generates a string representation of this type.
	 *
	 * @return string rep
	 */
	public String toString() {
		return getClass().getName() + '(' + getAssociatedEntityName() + ')';
	}

	/**
	 * For entity types, the name correlates to the associated entity name.
	 */
	public String getName() {
		return associatedEntityName;
	}

	/**
	 * Does this association foreign key reference the primary key of the other table?
	 * Otherwise, it references a property-ref.
	 *
	 * @return True if this association reference the PK of the associated entity.
	 */
	public boolean isReferenceToPrimaryKey() {
		return uniqueKeyPropertyName==null;
	}

	public String getRHSUniqueKeyPropertyName() {
		return uniqueKeyPropertyName;
	}

	public String getLHSPropertyName() {
		return null;
	}

	public String getPropertyName() {
		return null;
	}

	/**
	 * The name of the associated entity.
	 *
	 * @return The associated entity name.
	 */
	public final String getAssociatedEntityName() {
		return associatedEntityName;
	}

	/**
	 * The name of the associated entity.
	 *
	 * @param factory The session factory, for resolution.
	 * @return The associated entity name.
	 */
	public String getAssociatedEntityName(SessionFactoryImplementor factory) {
		return getAssociatedEntityName();
	}

	/**
	 * Retrieves the {@link Joinable} defining the associated entity.
	 *
	 * @param factory The session factory.
	 * @return The associated joinable
	 * @throws MappingException Generally indicates an invalid entity name.
	 */
	public Joinable getAssociatedJoinable(SessionFactoryImplementor factory) throws MappingException {
		return ( Joinable ) factory.getEntityPersister( associatedEntityName );
	}

	/**
	 * This returns the wrong class for an entity with a proxy, or for a named
	 * entity.  Theoretically it should return the proxy class, but it doesn't.
	 * <p/>
	 * The problem here is that we do not necessarily have a ref to the associated
	 * entity persister (nor to the session factory, to look it up) which is really
	 * needed to "do the right thing" here...
	 *
	 * @return The entiyt class.
	 */
	public final Class getReturnedClass() {
		if ( returnedClass == null ) {
			returnedClass = determineAssociatedEntityClass();
		}
		return returnedClass;
	}

	private Class determineAssociatedEntityClass() {
		try {
			return ReflectHelper.classForName( getAssociatedEntityName() );
		}
		catch ( ClassNotFoundException cnfe ) {
			return java.util.Map.class;
		}
	}

	/**
	 * {@inheritDoc}
	 */
	public Object nullSafeGet(ResultSet rs, String name, SessionImplementor session, Object owner)
	throws HibernateException, SQLException {
		return nullSafeGet( rs, new String[] {name}, session, owner );
	}

	/**
	 * {@inheritDoc}
	 */
	public final Object nullSafeGet(
			ResultSet rs,
			String[] names,
			SessionImplementor session,
			Object owner) throws HibernateException, SQLException {
		return resolve( hydrate(rs, names, session, owner), session, owner );
	}

	/**
	 * Two entities are considered the same when their instances are the same.
	 *
	 * @param x One entity instance
	 * @param y Another entity instance
	 * @param entityMode The entity mode.
	 * @return True if x == y; false otherwise.
	 */
	public final boolean isSame(Object x, Object y, EntityMode entityMode) {
		return x == y;
	}

	/**
	 * {@inheritDoc}
	 */
	public int compare(Object x, Object y, EntityMode entityMode) {
		return 0; //TODO: entities CAN be compared, by PK, fix this! -> only if/when we can extract the id values....
	}

	/**
	 * {@inheritDoc}
	 */
	public Object deepCopy(Object value, EntityMode entityMode, SessionFactoryImplementor factory) {
		return value; //special case ... this is the leaf of the containment graph, even though not immutable
	}

	/**
	 * {@inheritDoc}
	 */
	public Object replace(
			Object original,
			Object target,
			SessionImplementor session,
			Object owner,
			Map copyCache) throws HibernateException {
		if ( original == null ) {
			return null;
		}
		Object cached = copyCache.get(original);
		if ( cached != null ) {
			return cached;
		}
		else {
			if ( original == target ) {
				return target;
			}
			Object id = getIdentifier( original, session );
			if ( id == null ) {
				throw new AssertionFailure("cannot copy a reference to an object with a null id");
			}
			id = getIdentifierOrUniqueKeyType( session.getFactory() )
					.replace(id, null, session, owner, copyCache);
			return resolve( id, session, owner );
		}
	}

	/**
	 * {@inheritDoc}
	 */
	public int getHashCode(Object x, EntityMode entityMode, SessionFactoryImplementor factory) {
		EntityPersister persister = factory.getEntityPersister(associatedEntityName);
		if ( !persister.canExtractIdOutOfEntity() ) {
			return super.getHashCode(x, entityMode);
		}

		final Serializable id;
		if (x instanceof HibernateProxy) {
			id = ( (HibernateProxy) x ).getHibernateLazyInitializer().getIdentifier();
		}
		else {
			id = persister.getIdentifier(x, entityMode);
		}
		return persister.getIdentifierType().getHashCode(id, entityMode, factory);
	}

	/**
	 * {@inheritDoc}
	 */
	public boolean isEqual(Object x, Object y, EntityMode entityMode, SessionFactoryImplementor factory) {
		EntityPersister persister = factory.getEntityPersister(associatedEntityName);
		if ( !persister.canExtractIdOutOfEntity() ) {
			return super.isEqual(x, y, entityMode);
		}

		Serializable xid;
		if (x instanceof HibernateProxy) {
			xid = ( (HibernateProxy) x ).getHibernateLazyInitializer()
					.getIdentifier();
		}
		else {
			xid = persister.getIdentifier(x, entityMode);
		}

		Serializable yid;
		if (y instanceof HibernateProxy) {
			yid = ( (HibernateProxy) y ).getHibernateLazyInitializer()
					.getIdentifier();
		}
		else {
			yid = persister.getIdentifier(y, entityMode);
		}