Hibernate example source code file (BlobTypeDescriptor.java)

This example Hibernate source code file (BlobTypeDescriptor.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

blob, blob, blobmutabilityplan, blobmutabilityplan, blobs, blobtypedescriptor, blobtypedescriptor, hibernateexception, io, jdbc, override, sql, sqlexception, unable, util, wrapperoptions, x, x

The Hibernate BlobTypeDescriptor.java source code

/*
 * Hibernate, Relational Persistence for Idiomatic Java
 *
 * Copyright (c) 2010, Red Hat Inc. 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 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.type.descriptor.java;

import java.io.Serializable;
import java.sql.Blob;
import java.sql.SQLException;
import java.util.Comparator;

import org.hibernate.HibernateException;
import org.hibernate.engine.jdbc.BlobProxy;
import org.hibernate.engine.jdbc.WrappedBlob;
import org.hibernate.type.descriptor.BinaryStream;
import org.hibernate.type.descriptor.WrapperOptions;

/**
 * Descriptor for {@link Blob} handling.
 * <p/>
 * Note, {@link Blob blobs} really are mutable (their internal state can in fact be mutated).  We simply
 * treat them as immutable because we cannot properly check them for changes nor deep copy them.
 *
 * @author Steve Ebersole
 */
public class BlobTypeDescriptor extends AbstractTypeDescriptor<Blob> {
	public static final BlobTypeDescriptor INSTANCE = new BlobTypeDescriptor();

	public static class BlobMutabilityPlan implements MutabilityPlan<Blob> {
		public static final BlobMutabilityPlan INSTANCE = new BlobMutabilityPlan();

		public boolean isMutable() {
			return false;
		}

		public Blob deepCopy(Blob value) {
			return value;
		}

		public Serializable disassemble(Blob value) {
			throw new UnsupportedOperationException( "Blobs are not cacheable" );
		}

		public Blob assemble(Serializable cached) {
			throw new UnsupportedOperationException( "Blobs are not cacheable" );
		}
	}

	public BlobTypeDescriptor() {
		super( Blob.class, BlobMutabilityPlan.INSTANCE );
	}

	/**
	 * {@inheritDoc}
	 */
	public String toString(Blob value) {
		final byte[] bytes;
		try {
			bytes = DataHelper.extractBytes( value.getBinaryStream() );
		}
		catch ( SQLException e ) {
			throw new HibernateException( "Unable to access blob stream", e );
		}
		return PrimitiveByteArrayTypeDescriptor.INSTANCE.toString( bytes );
	}

	/**
	 * {@inheritDoc}
	 */
	public Blob fromString(String string) {
		return BlobProxy.generateProxy( PrimitiveByteArrayTypeDescriptor.INSTANCE.fromString( string ) );
	}

	@Override
	@SuppressWarnings({ "unchecked" })
	public Comparator<Blob> getComparator() {
		return IncomparableComparator.INSTANCE;
	}

	@Override
	public int extractHashCode(Blob value) {
		return System.identityHashCode( value );
	}

	@Override
	public boolean areEqual(Blob one, Blob another) {
		return one == another;
	}

	@SuppressWarnings({ "unchecked" })
	public <X> X unwrap(Blob value, Class type, WrapperOptions options) {
		if ( ! ( Blob.class.isAssignableFrom( type ) || BinaryStream.class.isAssignableFrom( type ) ) ) {
			throw unknownUnwrap( type );
		}

		if ( value == null ) {
			return null;
		}

		if ( BinaryStream.class.isAssignableFrom( type ) ) {
			try {
				return (X) new BinaryStreamImpl( DataHelper.extractBytes( value.getBinaryStream() ) );
			}
			catch ( SQLException e ) {
				throw new HibernateException( "Unable to access blob stream", e );
			}
		}

		final Blob blob =  WrappedBlob.class.isInstance( value )
				? ( (WrappedBlob) value ).getWrappedBlob()
				: value;
		return (X) blob;
	}

	public <X> Blob wrap(X value, WrapperOptions options) {
		if ( value == null ) {
			return null;
		}

		if ( ! Blob.class.isAssignableFrom( value.getClass() ) ) {
			throw unknownWrap( value.getClass() );
		}

		return options.getLobCreator().wrap( (Blob) value );
	}
}