collectiontype.java

介绍了hibernate的入门有一些基本常用的事例

// $Id: CollectionType.java,v 1.28 2005/04/03 15:55:03 oneovthafew Exp $
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.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 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, CollectionPersister persister,
			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!
	 */
	public abstract PersistentCollection instantiate(SessionImplementor session,
			CollectionPersister persister, Serializable key) throws HibernateException;

	public Object nullSafeGet(ResultSet rs, String name, SessionImplementor session, Object owner)
			throws HibernateException, 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";
		
		if ( Hibernate.isInitialized( value ) ) {
			if ( getReturnedClass().isInstance(value) ) {
				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();
			}
			else {
				// for DOM4J "collections" only
				return ( (Element) value ).asXML(); //TODO: it would be better if this was done at the higher level by Printer
			}
		}
		else {
			return "<uninitialized>";
		}
		
	}

	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
	 */
	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
	 */
	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?
	 */
	private boolean isOwnerVersioned(SessionImplementor session) throws MappingException {
		return getPersister( session )
			.getOwnerEntityPersister()
			.isVersioned();
	}

	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;

	}

	/**
	 * Wrap the naked collection instance in a wrapper, or instantiate a holder. Callers MUST add
	 * the holder to the persistence context!