91 lines
3.2 KiB
Java
91 lines
3.2 KiB
Java
/* java.beans.PersistenceDelegate
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Copyright (C) 2005 Free Software Foundation, Inc.
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This file is part of GNU Classpath.
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GNU Classpath is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GNU Classpath is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU Classpath; see the file COPYING. If not, write to the
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Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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02110-1301 USA.
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Linking this library statically or dynamically with other modules is
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making a combined work based on this library. Thus, the terms and
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conditions of the GNU General Public License cover the whole
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combination.
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As a special exception, the copyright holders of this library give you
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permission to link this library with independent modules to produce an
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executable, regardless of the license terms of these independent
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modules, and to copy and distribute the resulting executable under
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terms of your choice, provided that you also meet, for each linked
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independent module, the terms and conditions of the license of that
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module. An independent module is a module which is not derived from
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or based on this library. If you modify this library, you may extend
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this exception to your version of the library, but you are not
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obligated to do so. If you do not wish to do so, delete this
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exception statement from your version. */
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package java.beans;
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/** <p>A <code>PersistenceDelegate</code> describes how a another object
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* has to constructed and transformed in order to create a complete
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* replicate.</p>
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*
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* <p>For custom classes you will need to implement
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* <code>PersistenceDelegate</code> in a way that is suitable for them.
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* To make use of the implementation you have to register it with an
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* {@link Encoder} using the {Encoder#setPersistenceDelegate} method.</p>
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*
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* @author Robert Schuster (robertschuster@fsfe.org)
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* @since 1.4
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*/
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public abstract class PersistenceDelegate
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{
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protected void initialize(Class<?> type, Object oldInstance,
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Object newInstance, Encoder out)
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{
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if (type != Object.class)
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{
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type = type.getSuperclass();
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PersistenceDelegate pd = out.getPersistenceDelegate(type);
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pd.initialize(type, oldInstance, newInstance, out);
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}
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}
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public void writeObject(Object oldInstance, Encoder out)
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{
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Object streamCandidate = out.get(oldInstance);
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if (mutatesTo(oldInstance, streamCandidate))
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{
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initialize(oldInstance.getClass(), oldInstance, streamCandidate, out);
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}
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else
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{
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out.remove(oldInstance);
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out.writeExpression(instantiate(oldInstance, out));
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}
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}
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protected boolean mutatesTo(Object oldInstance, Object newInstance)
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{
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return (newInstance != null)
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&& oldInstance.getClass() == newInstance.getClass();
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}
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protected abstract Expression instantiate(Object oldInstance, Encoder out);
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}
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