001/*
002 * Copyright (c) 2005 Einar Pehrson <einar@pehrson.nu>.
003 *
004 * This file is part of
005 * CleanSheets - a spreadsheet application for the Java platform.
006 *
007 * CleanSheets is free software; you can redistribute it and/or modify
008 * it under the terms of the GNU General Public License as published by
009 * the Free Software Foundation; either version 2 of the License, or
010 * (at your option) any later version.
011 *
012 * CleanSheets is distributed in the hope that it will be useful,
013 * but WITHOUT ANY WARRANTY; without even the implied warranty of
014 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
015 * GNU General Public License for more details.
016 *
017 * You should have received a copy of the GNU General Public License
018 * along with CleanSheets; if not, write to the Free Software
019 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
020 */
021package csheets.io;
022
023import java.io.IOException;
024import java.io.InputStream;
025import java.io.ObjectInputStream;
026import java.io.ObjectStreamClass;
027
028/**
029 * An object input stream that resolves class descriptors through a given
030 * class loader, and thereby allowing dynamic deserialization.
031 * @author Einar Pehrson
032 */
033public class DynamicObjectInputStream extends ObjectInputStream {
034
035        /** The class loader queried for class descriptor resolution */
036        private ClassLoader loader;
037
038        /**
039         * Creates a new dynamic object input stream.
040         * @param stream the input stream to read from
041         * @param loader the class loader queried for class descriptor resolution
042         * @throws IOException if an I/O error occurs while reading stream header
043         */
044        public DynamicObjectInputStream(InputStream stream, ClassLoader loader)
045                        throws IOException {
046                super(stream);
047                this.loader = loader;
048        }
049
050        /**
051         * Load the local class equivalent of the specified stream class descriptor,
052         * by first querying the given class loader.
053         * @param desc the class descriptor
054         * @throws IOException if an I/O error occurs while resolving
055         * @throws ClassNotFoundException if the class of a serialized object cannot be found
056         */
057        protected Class<?> resolveClass(ObjectStreamClass desc) throws IOException,
058                ClassNotFoundException {
059                try {
060                        return Class.forName(desc.getName(), false, loader);
061                } catch (ClassNotFoundException ex) {
062                        return super.resolveClass(desc);
063                }
064        }
065}