Hibernate example source code file (JavassistInstrumenter.java)

This example Hibernate source code file (JavassistInstrumenter.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

basicclassfilter, bytecodeproviderimpl, class_filter, classdescriptor, classdescriptor, classfile, customclassdescriptor, customclassdescriptor, io, ioexception, ioexception, javassistinstrumenter, override, string, string, util

The Hibernate JavassistInstrumenter.java source code

/*
 * Hibernate, Relational Persistence for Idiomatic Java
 *
 * Copyright (c) 2009-2011, 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.bytecode.buildtime.internal;

import java.io.ByteArrayInputStream;
import java.io.DataInputStream;
import java.io.IOException;
import java.util.Set;

import javassist.bytecode.ClassFile;

import org.hibernate.bytecode.buildtime.spi.AbstractInstrumenter;
import org.hibernate.bytecode.buildtime.spi.BasicClassFilter;
import org.hibernate.bytecode.buildtime.spi.ClassDescriptor;
import org.hibernate.bytecode.buildtime.spi.Logger;
import org.hibernate.bytecode.internal.javassist.BytecodeProviderImpl;
import org.hibernate.bytecode.internal.javassist.FieldHandled;
import org.hibernate.bytecode.spi.ClassTransformer;

/**
 * Strategy for performing build-time instrumentation of persistent classes in order to enable
 * field-level interception using Javassist.
 *
 * @author Steve Ebersole
 * @author Muga Nishizawa
 */
public class JavassistInstrumenter extends AbstractInstrumenter {

	private static final BasicClassFilter CLASS_FILTER = new BasicClassFilter();

	private final BytecodeProviderImpl provider = new BytecodeProviderImpl();

	public JavassistInstrumenter(Logger logger, Options options) {
		super( logger, options );
	}

	@Override
    protected ClassDescriptor getClassDescriptor(byte[] bytecode) throws IOException {
		return new CustomClassDescriptor( bytecode );
	}

	@Override
    protected ClassTransformer getClassTransformer(ClassDescriptor descriptor, Set classNames) {
		if ( descriptor.isInstrumented() ) {
			logger.debug( "class [" + descriptor.getName() + "] already instrumented" );
			return null;
		}
		else {
			return provider.getTransformer( CLASS_FILTER, new CustomFieldFilter( descriptor, classNames ) );
		}
	}

	private static class CustomClassDescriptor implements ClassDescriptor {
		private final byte[] bytes;
		private final ClassFile classFile;

		public CustomClassDescriptor(byte[] bytes) throws IOException {
			this.bytes = bytes;
			this.classFile = new ClassFile( new DataInputStream( new ByteArrayInputStream( bytes ) ) );
		}

		public String getName() {
			return classFile.getName();
		}

		public boolean isInstrumented() {
			String[] interfaceNames = classFile.getInterfaces();
			for ( String interfaceName : interfaceNames ) {
				if ( FieldHandled.class.getName().equals( interfaceName ) ) {
					return true;
				}
			}
			return false;
		}

		public byte[] getBytes() {
			return bytes;
		}
	}

}