collectiontype.java

一个Java持久层类库

// $Id: CollectionType.java 11302 2007-03-19 20:44:11Z [e-mail] $
package org.hibernate.type;

import java.io.Serializable;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

import org.dom4j.Element;
import org.dom4j.Node;

import org.hibernate.EntityMode;
import org.hibernate.Hibernate;
import org.hibernate.HibernateException;
import org.hibernate.MappingException;
import org.hibernate.collection.PersistentCollection;
import org.hibernate.engine.CollectionKey;
import org.hibernate.engine.EntityEntry;
import org.hibernate.engine.Mapping;
import org.hibernate.engine.PersistenceContext;
import org.hibernate.engine.SessionFactoryImplementor;
import org.hibernate.engine.SessionImplementor;
import org.hibernate.persister.collection.CollectionPersister;
import org.hibernate.persister.collection.QueryableCollection;
import org.hibernate.persister.entity.EntityPersister;
import org.hibernate.persister.entity.Joinable;
import org.hibernate.proxy.HibernateProxy;
import org.hibernate.proxy.LazyInitializer;
import org.hibernate.util.ArrayHelper;
import org.hibernate.util.MarkerObject;

/**
 * A type that handles Hibernate <tt>PersistentCollection</tt>s (including arrays).
 * 
 * @author Gavin King
 */
public abstract class CollectionType extends AbstractType implements AssociationType {

	private static final Object NOT_NULL_COLLECTION = new MarkerObject( "NOT NULL COLLECTION" );
	public static final Object UNFETCHED_COLLECTION = new MarkerObject( "UNFETCHED COLLECTION" );

	private final String role;
	private final String foreignKeyPropertyName;
	private final boolean isEmbeddedInXML;

	public CollectionType(String role, String foreignKeyPropertyName, boolean isEmbeddedInXML) {
		this.role = role;
		this.foreignKeyPropertyName = foreignKeyPropertyName;
		this.isEmbeddedInXML = isEmbeddedInXML;
	}
	
	public boolean isEmbeddedInXML() {
		return isEmbeddedInXML;
	}

	public String getRole() {
		return role;
	}

	public Object indexOf(Object collection, Object element) {
		throw new UnsupportedOperationException( "generic collections don't have indexes" );
	}

	public boolean contains(Object collection, Object childObject, SessionImplementor session) {
		// we do not have to worry about queued additions to uninitialized
		// collections, since they can only occur for inverse collections!
		Iterator elems = getElementsIterator( collection, session );
		while ( elems.hasNext() ) {
			Object element = elems.next();
			// worrying about proxies is perhaps a little bit of overkill here...
			if ( element instanceof HibernateProxy ) {
				LazyInitializer li = ( (HibernateProxy) element ).getHibernateLazyInitializer();
				if ( !li.isUninitialized() ) element = li.getImplementation();
			}
			if ( element == childObject ) return true;
		}
		return false;
	}

	public boolean isCollectionType() {
		return true;
	}

	public final boolean isEqual(Object x, Object y, EntityMode entityMode) {
		return x == y
			|| ( x instanceof PersistentCollection && ( (PersistentCollection) x ).isWrapper( y ) )
			|| ( y instanceof PersistentCollection && ( (PersistentCollection) y ).isWrapper( x ) );
	}

	public int compare(Object x, Object y, EntityMode entityMode) {
		return 0; // collections cannot be compared
	}

	public int getHashCode(Object x, EntityMode entityMode) {
		throw new UnsupportedOperationException( "cannot perform lookups on collections" );
	}

	/**
	 * Instantiate an uninitialized collection wrapper or holder. Callers MUST add the holder to the
	 * persistence context!
	 *
	 * @param session The session from which the request is originating.
	 * @param persister The underlying collection persister (metadata)
	 * @param key The owner key.
	 * @return The instantiated collection.
	 */
	public abstract PersistentCollection instantiate(SessionImplementor session, CollectionPersister persister, Serializable key);

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

	public Object nullSafeGet(ResultSet rs, String[] name, SessionImplementor session, Object owner)
			throws HibernateException, SQLException {
		return resolve( null, session, owner );
	}

	public final void nullSafeSet(PreparedStatement st, Object value, int index, boolean[] settable,
			SessionImplementor session) throws HibernateException, SQLException {
		//NOOP
	}

	public void nullSafeSet(PreparedStatement st, Object value, int index,
			SessionImplementor session) throws HibernateException, SQLException {
	}

	public int[] sqlTypes(Mapping session) throws MappingException {
		return ArrayHelper.EMPTY_INT_ARRAY;
	}

	public int getColumnSpan(Mapping session) throws MappingException {
		return 0;
	}

	public String toLoggableString(Object value, SessionFactoryImplementor factory)
			throws HibernateException {
		if ( value == null ) {
			return "null";
		}
		else if ( !Hibernate.isInitialized( value ) ) {
			return "<uninitialized>";
		}
		else {
			return renderLoggableString( value, factory );
		}
	}

	protected String renderLoggableString(Object value, SessionFactoryImplementor factory)
			throws HibernateException {
		if ( Element.class.isInstance( value ) ) {
			// for DOM4J "collections" only
			// TODO: it would be better if this was done at the higher level by Printer
			return ( ( Element ) value ).asXML();
		}
		else {
			List list = new ArrayList();
			Type elemType = getElementType( factory );
			Iterator iter = getElementsIterator( value );
			while ( iter.hasNext() ) {
				list.add( elemType.toLoggableString( iter.next(), factory ) );
			}
			return list.toString();
		}
	}

	public Object deepCopy(Object value, EntityMode entityMode, SessionFactoryImplementor factory)
			throws HibernateException {
		return value;
	}

	public String getName() {
		return getReturnedClass().getName() + '(' + getRole() + ')';
	}

	/**
	 * Get an iterator over the element set of the collection, which may not yet be wrapped
	 *
	 * @param collection The collection to be iterated
	 * @param session The session from which the request is originating.
	 * @return The iterator.
	 */
	public Iterator getElementsIterator(Object collection, SessionImplementor session) {
		if ( session.getEntityMode()==EntityMode.DOM4J ) {
			final SessionFactoryImplementor factory = session.getFactory();
			final CollectionPersister persister = factory.getCollectionPersister( getRole() );
			final Type elementType = persister.getElementType();
			
			List elements = ( (Element) collection ).elements( persister.getElementNodeName() );
			ArrayList results = new ArrayList();
			for ( int i=0; i<elements.size(); i++ ) {
				Element value = (Element) elements.get(i);
				results.add( elementType.fromXMLNode( value, factory ) );
			}
			return results.iterator();
		}
		else {
			return getElementsIterator(collection);
		}
	}

	/**
	 * Get an iterator over the element set of the collection in POJO mode
	 *
	 * @param collection The collection to be iterated
	 * @return The iterator.
	 */
	protected Iterator getElementsIterator(Object collection) {
		return ( (Collection) collection ).iterator();
	}

	public boolean isMutable() {
		return false;
	}

	public Serializable disassemble(Object value, SessionImplementor session, Object owner)
			throws HibernateException {
		//remember the uk value
		
		//This solution would allow us to eliminate the owner arg to disassemble(), but
		//what if the collection was null, and then later had elements added? seems unsafe
		//session.getPersistenceContext().getCollectionEntry( (PersistentCollection) value ).getKey();
		
		final Serializable key = getKeyOfOwner(owner, session);
		if (key==null) {
			return null;
		}
		else {
			return getPersister(session)
					.getKeyType()
					.disassemble( key, session, owner );
		}
	}

	public Object assemble(Serializable cached, SessionImplementor session, Object owner)
			throws HibernateException {
		//we must use the "remembered" uk value, since it is 
		//not available from the EntityEntry during assembly
		if (cached==null) {
			return null;
		}
		else {
			final Serializable key = (Serializable) getPersister(session)
					.getKeyType()
					.assemble( cached, session, owner);
			return resolveKey( key, session, owner );
		}
	}

	/**
	 * Is the owning entity versioned?
	 *
	 * @param session The session from which the request is originating.
	 * @return True if the collection owner is versioned; false otherwise.
	 * @throws org.hibernate.MappingException Indicates our persister could not be located.
	 */
	private boolean isOwnerVersioned(SessionImplementor session) throws MappingException {
		return getPersister( session ).getOwnerEntityPersister().isVersioned();
	}

	/**
	 * Get our underlying collection persister (using the session to access the
	 * factory).
	 *
	 * @param session The session from which the request is originating.
	 * @return The underlying collection persister
	 */
	private CollectionPersister getPersister(SessionImplementor session) {
		return session.getFactory().getCollectionPersister( role );
	}

	public boolean isDirty(Object old, Object current, SessionImplementor session)
			throws HibernateException {

		// collections don't dirty an unversioned parent entity

		// TODO: I don't really like this implementation; it would be better if
		// this was handled by searchForDirtyCollections()
		return isOwnerVersioned( session ) && super.isDirty( old, current, session );
		// return false;

	}

	public boolean isDirty(Object old, Object current, boolean[] checkable, SessionImplementor session)
			throws HibernateException {
		return isDirty(old, current, session);
	}

	/**
	 * Wrap the naked collection instance in a wrapper, or instantiate a
	 * holder. Callers <b>MUST</b> add the holder to the persistence context!
	 *
	 * @param session The session from which the request is originating.
	 * @param collection The bare collection to be wrapped.
	 * @return The wrapped collection.
	 */
	public abstract PersistentCollection wrap(SessionImplementor session, Object collection);

	/**
	 * Note: return true because this type is castable to <tt>AssociationType</tt>. Not because
	 * all collections are associations.
	 */
	public boolean isAssociationType() {
		return true;
	}

	public ForeignKeyDirection getForeignKeyDirection() {
		return ForeignKeyDirection.FOREIGN_KEY_TO_PARENT;
	}

	/**
	 * Get the key value from the owning entity instance, usually the identifier, but might be some
	 * other unique key, in the case of property-ref
	 *
	 * @param owner The collection owner
	 * @param session The session from which the request is originating.
	 * @return The collection owner's key
	 */
	public Serializable getKeyOfOwner(Object owner, SessionImplementor session) {
		
		EntityEntry entityEntry = session.getPersistenceContext().getEntry( owner );
		if ( entityEntry == null ) return null; // This just handles a particular case of component
									  // projection, perhaps get rid of it and throw an exception
		
		if ( foreignKeyPropertyName == null ) {
			return entityEntry.getId();
		}
		else {
			// TODO: at the point where we are resolving collection references, we don't
			// know if the uk value has been resolved (depends if it was earlier or
			// later in the mapping document) - now, we could try and use e.getStatus()
			// to decide to semiResolve(), trouble is that initializeEntity() reuses
			// the same array for resolved and hydrated values
			Object id;
			if ( entityEntry.getLoadedState() != null ) {
				id = entityEntry.getLoadedValue( foreignKeyPropertyName );
			}