01: /*
02: * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
03: *
04: * // Copyright (c) 1998, 2007, Oracle. All rights reserved.
05: *
06: *
07: * The contents of this file are subject to the terms of either the GNU
08: * General Public License Version 2 only ("GPL") or the Common Development
09: * and Distribution License("CDDL") (collectively, the "License"). You
10: * may not use this file except in compliance with the License. You can obtain
11: * a copy of the License at https://glassfish.dev.java.net/public/CDDL+GPL.html
12: * or glassfish/bootstrap/legal/LICENSE.txt. See the License for the specific
13: * language governing permissions and limitations under the License.
14: *
15: * When distributing the software, include this License Header Notice in each
16: * file and include the License file at glassfish/bootstrap/legal/LICENSE.txt.
17: * Sun designates this particular file as subject to the "Classpath" exception
18: * as provided by Sun in the GPL Version 2 section of the License file that
19: * accompanied this code. If applicable, add the following below the License
20: * Header, with the fields enclosed by brackets [] replaced by your own
21: * identifying information: "Portions Copyrighted [year]
22: * [name of copyright owner]"
23: *
24: * Contributor(s):
25: *
26: * If you wish your version of this file to be governed by only the CDDL or
27: * only the GPL Version 2, indicate your decision by adding "[Contributor]
28: * elects to include this software in this distribution under the [CDDL or GPL
29: * Version 2] license." If you don't indicate a single choice of license, a
30: * recipient has the option to distribute your version of this file under
31: * either the CDDL, the GPL Version 2 or to extend the choice of license to
32: * its licensees as provided above. However, if you add GPL Version 2 code
33: * and therefore, elected the GPL Version 2 license, then the option applies
34: * only if the new code is made subject to such option by the copyright
35: * holder.
36: */
37: package oracle.toplink.essentials.internal.indirection;
38:
39: import oracle.toplink.essentials.indirection.*;
40:
41: /**
42: * Used as the backup value holder in the unit of work for transparent indirection.
43: * This ensure that a reference to the original value holder is held in case the
44: * transparent collection or proxy is replace without first instantiating the original.
45: *
46: * @since 10.1.3
47: * @author James Sutherland
48: */
49: public class BackupValueHolder extends ValueHolder {
50:
51: /** Stores the original uow clone's value holder. */
52: protected ValueHolderInterface unitOfWorkValueHolder;
53:
54: public BackupValueHolder(ValueHolderInterface unitOfWorkValueHolder) {
55: this .unitOfWorkValueHolder = unitOfWorkValueHolder;
56: }
57:
58: /**
59: * If the original value holder was not instantiated,
60: * then first instantiate it to obtain the backup value.
61: */
62: public Object getValue() {
63: // Ensures instantiation of the original, and setting of this back value holder's value.
64: getUnitOfWorkValueHolder().getValue();
65: return value;
66: }
67:
68: /**
69: * Return the original uow clone's value holder.
70: */
71: public ValueHolderInterface getUnitOfWorkValueHolder() {
72: return unitOfWorkValueHolder;
73: }
74: }
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