Hibernate example source code file (MapKeyHelpers.java)

This example Hibernate source code file (MapKeyHelpers.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

bindable, class, io, mapattribute, mapkeyattribute, mapkeyattribute, mapkeysource, mapkeysource, override, override, pathimplementor, reflection, serializable, string, util, v, v

The Hibernate MapKeyHelpers.java source code

/*
 * Hibernate, Relational Persistence for Idiomatic Java
 *
 * Copyright (c) 2009 by Red Hat Inc and/or its affiliates or by
 * third-party contributors as indicated by either @author tags or express
 * copyright attribution statements applied by the authors.  All
 * third-party contributions are distributed under license by Red Hat Inc.
 *
 * 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.ejb.criteria.path;
import java.io.Serializable;
import java.lang.reflect.Member;
import java.util.Map;
import javax.persistence.criteria.Join;
import javax.persistence.criteria.MapJoin;
import javax.persistence.criteria.Path;
import javax.persistence.metamodel.Attribute;
import javax.persistence.metamodel.Bindable;
import javax.persistence.metamodel.ManagedType;
import javax.persistence.metamodel.MapAttribute;
import javax.persistence.metamodel.SingularAttribute;
import javax.persistence.metamodel.Type;
import org.hibernate.ejb.criteria.CriteriaBuilderImpl;
import org.hibernate.ejb.criteria.MapJoinImplementor;
import org.hibernate.ejb.criteria.PathImplementor;
import org.hibernate.engine.spi.SessionFactoryImplementor;
import org.hibernate.persister.collection.CollectionPersister;

/**
 * {@link MapJoin#key} poses a number of implementation difficulties in terms of the type signatures
 * amongst the {@link Path}, {@link Join} and {@link Attribute} reference at play.  The implementations found here
 * provide that bridge.
 *
 * @author Steve Ebersole
 */
public class MapKeyHelpers {

	/**
	 * Models a path to a map key.  This is the actual return used from {@link MapJoin#key}
	 *
	 * @param <K> The type of the map key.
	 */
	public static class MapKeyPath<K>
			extends AbstractPathImpl<K>
			implements PathImplementor<K>, Serializable {

		private final MapKeyAttribute<K> mapKeyAttribute;

		public MapKeyPath(
				CriteriaBuilderImpl criteriaBuilder,
				MapKeySource<K,?> source,
				MapKeyAttribute<K> mapKeyAttribute) {
			super( criteriaBuilder, mapKeyAttribute.getJavaType(), source );
			this.mapKeyAttribute = mapKeyAttribute;
		}

		@Override
		public MapKeySource getPathSource() {
			return (MapKeySource) super.getPathSource();
		}

		public MapKeyAttribute<K> getAttribute() {
			return mapKeyAttribute;
		}

		private boolean isBasicTypeKey() {
			return Attribute.PersistentAttributeType.BASIC ==
					mapKeyAttribute.getPersistentAttributeType();
		}

		@Override
		protected boolean canBeDereferenced() {
			return ! isBasicTypeKey();
		}

		@Override
		protected Attribute locateAttributeInternal(String attributeName) {
			if ( ! canBeDereferenced() ) {
				throw new IllegalArgumentException(
						"Map key [" + getPathSource().getPathIdentifier() + "] cannot be dereferenced"
				);
			}
			throw new UnsupportedOperationException( "Not yet supported!" );
		}

		public Bindable<K> getModel() {
			return mapKeyAttribute;
		}
	}

	/**
	 * Defines a {@link Path} for the map which can then be used to represent the source of the
	 * map key "attribute".
	 *
	 * @param <K> The map key type
	 * @param <V> The map value type
	 */
	public static class MapKeySource<K,V>
			extends AbstractPathImpl<Map
			implements PathImplementor<Map, Serializable {

		private final MapAttribute<?,K,V> mapAttribute;
		private final MapJoinImplementor<?,K,V> mapJoin;

		public MapKeySource(
				CriteriaBuilderImpl criteriaBuilder,
				Class<Map javaType,
				MapJoinImplementor<?,K,V> mapJoin,
				MapAttribute<?,K,V> attribute) {
			super( criteriaBuilder, javaType, null );
			this.mapJoin = mapJoin;
			this.mapAttribute = attribute;
		}

		public MapAttribute<?,K,V> getAttribute() {
			return mapAttribute;
		}

		@SuppressWarnings({ "unchecked" })
		public Bindable<Map getModel() {
			// TODO : ok???  the attribute is in fact bindable, but its type signature is different
			return (Bindable<Map) mapAttribute;
		}

		@Override
		public PathImplementor<?> getParentPath() {
			return (PathImplementor<?>) mapJoin.getParentPath();
		}

		@Override
		protected boolean canBeDereferenced() {
			return false;
		}

		@Override
		protected Attribute locateAttributeInternal(String attributeName) {
			throw new IllegalArgumentException( "Map [" + mapJoin.getPathIdentifier() + "] cannot be dereferenced" );
		}

	}

	/**
	 * Disallow instantiation
	 */
	private MapKeyHelpers() {
	}

	/**
	 * Defines an {@link javax.persistence.metamodel.Attribute} modelling of a map-key.
	 *
	 * @param <K> The type of the map key
	 */
	public static class MapKeyAttribute<K>
			implements SingularAttribute<Map, Bindable, Serializable {
		private final MapAttribute<?,K,?> attribute;
		private final CollectionPersister mapPersister;
		private final org.hibernate.type.Type mapKeyType;
		private final Type<K> jpaType;
		private final BindableType jpaBindableType;
		private final Class<K> jpaBinableJavaType;
		private final PersistentAttributeType persistentAttributeType;

		public MapKeyAttribute(CriteriaBuilderImpl criteriaBuilder, MapAttribute<?, K, ?> attribute) {
			this.attribute = attribute;
			this.jpaType = attribute.getKeyType();
			this.jpaBinableJavaType = attribute.getKeyJavaType();
			this.jpaBindableType = Type.PersistenceType
					.ENTITY.equals( jpaType.getPersistenceType() )
					? BindableType.ENTITY_TYPE
					: BindableType.SINGULAR_ATTRIBUTE;

			String guessedRoleName = determineRole( attribute );
			SessionFactoryImplementor sfi = (SessionFactoryImplementor)
					criteriaBuilder.getEntityManagerFactory().getSessionFactory();
			mapPersister = sfi.getCollectionPersister( guessedRoleName );
			if ( mapPersister == null ) {
				throw new IllegalStateException( "Could not locate collection persister [" + guessedRoleName + "]" );
			}
			mapKeyType = mapPersister.getIndexType();
			if ( mapKeyType == null ) {
				throw new IllegalStateException( "Could not determine map-key type [" + guessedRoleName + "]" );
			}

			this.persistentAttributeType = mapKeyType.isEntityType()
					? PersistentAttributeType.MANY_TO_ONE
					: mapKeyType.isComponentType()
							? PersistentAttributeType.EMBEDDED
							: PersistentAttributeType.BASIC;
		}

		private String determineRole(MapAttribute<?,K,?> attribute) {
			return attribute.getDeclaringType().getJavaType().getName() +
					'.' + attribute.getName();
		}

		/**
		 * {@inheritDoc}
		 */
		public String getName() {
			// TODO : ???
			return "map-key";
		}

		/**
		 * {@inheritDoc}
		 */
		public PersistentAttributeType getPersistentAttributeType() {
			return persistentAttributeType;
		}

		/**
		 * {@inheritDoc}
		 */
		public ManagedType<Map getDeclaringType() {
			// TODO : ???
			return null;
		}

		/**
		 * {@inheritDoc}
		 */
		public Class<K> getJavaType() {
			return attribute.getKeyJavaType();
		}

		/**
		 * {@inheritDoc}
		 */
		public Member getJavaMember() {
			// TODO : ???
			return null;
		}

		/**
		 * {@inheritDoc}
		 */
		public boolean isAssociation() {
			return mapKeyType.isEntityType();
		}

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

		public boolean isId() {
			return false;
		}

		public boolean isVersion() {
			return false;
		}

		public boolean isOptional() {
			return false;
		}

		public Type<K> getType() {
			return jpaType;
		}

		public BindableType getBindableType() {
			return jpaBindableType;
		}

		public Class<K> getBindableJavaType() {
			return jpaBinableJavaType;
		}
	}
}