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Java > Open Source Codes > org > objectstyle > cayenne > TempObjectId


1 /* ====================================================================
2  *
3  * The ObjectStyle Group Software License, version 1.1
4  * ObjectStyle Group - http://objectstyle.org/
5  *
6  * Copyright (c) 2002-2005, Andrei (Andrus) Adamchik and individual authors
7  * of the software. All rights reserved.
8  *
9  * Redistribution and use in source and binary forms, with or without
10  * modification, are permitted provided that the following conditions
11  * are met:
12  *
13  * 1. Redistributions of source code must retain the above copyright
14  * notice, this list of conditions and the following disclaimer.
15  *
16  * 2. Redistributions in binary form must reproduce the above copyright
17  * notice, this list of conditions and the following disclaimer in
18  * the documentation and/or other materials provided with the
19  * distribution.
20  *
21  * 3. The end-user documentation included with the redistribution, if any,
22  * must include the following acknowlegement:
23  * "This product includes software developed by independent contributors
24  * and hosted on ObjectStyle Group web site (http://objectstyle.org/)."
25  * Alternately, this acknowlegement may appear in the software itself,
26  * if and wherever such third-party acknowlegements normally appear.
27  *
28  * 4. The names "ObjectStyle Group" and "Cayenne" must not be used to endorse
29  * or promote products derived from this software without prior written
30  * permission. For written permission, email
31  * "andrus at objectstyle dot org".
32  *
33  * 5. Products derived from this software may not be called "ObjectStyle"
34  * or "Cayenne", nor may "ObjectStyle" or "Cayenne" appear in their
35  * names without prior written permission.
36  *
37  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
38  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
39  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
40  * DISCLAIMED. IN NO EVENT SHALL THE OBJECTSTYLE GROUP OR
41  * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
42  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
43  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
44  * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
45  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
46  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
47  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
48  * SUCH DAMAGE.
49  * ====================================================================
50  *
51  * This software consists of voluntary contributions made by many
52  * individuals and hosted on ObjectStyle Group web site. For more
53  * information on the ObjectStyle Group, please see
54  * <http://objectstyle.org/>.
55  */
56 package org.objectstyle.cayenne;
57
58 import java.util.Collections JavaDoc;
59 import java.util.Map JavaDoc;
60
61 import org.apache.commons.lang.builder.EqualsBuilder;
62 import org.apache.commons.lang.builder.HashCodeBuilder;
63
64 /**
65  * An ObjectId for new objects that hasn't been committed to the external data store. On
66  * commit, a TempObjectId is replaced with a permanent ObjectId tied to a primary key of
67  * an object in the external data store.
68  *
69  * @author Andrei Adamchik
70  */
71 public class TempObjectId extends ObjectId {
72
73     protected byte[] key;
74
75     /**
76      * Creates a non-portable temporary ObjectId that should be replaced by a permanent id
77      * once a corresponding object is committed.
78      */
79     public TempObjectId(Class JavaDoc objectClass) {
80         super(objectClass, null);
81     }
82
83     /**
84      * Create a TempObjectId with a binary unique key. This id is "portable" in that it
85      * can be used across virtual machines to identify the same object.
86      *
87      * @since 1.2
88      */
89     public TempObjectId(Class JavaDoc objectClass, byte[] key) {
90         super(objectClass, null);
91         this.key = key;
92     }
93     
94     /**
95      * Returns a binary unique key for this id.
96      *
97      * @since 1.2
98      */
99     public byte[] getKey() {
100         return key;
101     }
102
103     /**
104      * TempObjectId equality condition is based on object reference comparison. This is
105      * possible since each object in a "new" state is unique, and TempObjectId is only
106      * used for "new" objects.
107      */
108     public boolean equals(Object JavaDoc object) {
109         // non-portable id
110 if (key == null) {
111             return object == this;
112         }
113
114         if (this == object) {
115             return true;
116         }
117
118         if (!(object instanceof TempObjectId)) {
119             return false;
120         }
121
122         TempObjectId id = (TempObjectId) object;
123         return new EqualsBuilder()
124                 .append(objectClass.getName(), id.objectClass.getName())
125                 .append(key, id.key)
126                 .isEquals();
127     }
128     
129     public int hashCode() {
130         if (this.hashCode == Integer.MIN_VALUE) {
131             // build and cache hashCode
132 HashCodeBuilder builder = new HashCodeBuilder(15, 37);
133
134             // use the class name because two ObjectId's should be equal
135 // even if their objClass'es were loaded by different class loaders.
136 builder.append(objectClass.getName().hashCode());
137
138             if (key != null) {
139                 builder.append(key);
140             }
141
142             this.hashCode = builder.toHashCode();
143         }
144
145         return this.hashCode;
146     }
147
148     /**
149      * Returns an empty map if there is no replacement id available, or a snapshot of a
150      * replacement id otherwise. Note that if a replacement id map is returned there is no
151      * guarantee that it is complete and has all keys.
152      */
153     public Map JavaDoc getIdSnapshot() {
154         return (replacementIdMap == null) ? Collections.EMPTY_MAP : replacementIdMap;
155     }
156
157     /**
158      * Always returns <code>true</code>.
159      */
160     public boolean isTemporary() {
161         return true;
162     }
163 }
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