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Java > Open Source Codes > org > objectstyle > cayenne > graph > BeanMergeHandler


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.
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17  * notice, this list of conditions and the following disclaimer in
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19  * distribution.
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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".
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34  * or "Cayenne", nor may "ObjectStyle" or "Cayenne" appear in their
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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.graph;
57
58 import java.util.Collection JavaDoc;
59
60 import org.apache.commons.beanutils.PropertyUtils;
61 import org.objectstyle.cayenne.CayenneRuntimeException;
62
63 /**
64  * GraphChangeHandler that works on top of a GraphMap, with callback methods implemented
65  * to modify objects in the graph, treating nodes and arcs as properties and using
66  * introspection.
67  *
68  * @since 1.2
69  * @author Andrus Adamchik
70  */
71 public class BeanMergeHandler implements GraphChangeHandler {
72
73     protected GraphMap graphMap;
74
75     public BeanMergeHandler(GraphMap graphMap) {
76         this.graphMap = graphMap;
77     }
78
79     /**
80      * Returns GraphMap used by this object to lookup graph nodes that need to be updated.
81      */
82     public GraphMap getGraphMap() {
83         return graphMap;
84     }
85
86     public void nodeIdChanged(Object JavaDoc nodeId, Object JavaDoc newId) {
87         Object JavaDoc node = graphMap.unregisterNode(nodeId);
88
89         if (node != null) {
90             graphMap.registerNode(newId, node);
91         }
92     }
93
94     /**
95      * Does nothing.
96      */
97     public void nodeCreated(Object JavaDoc nodeId) {
98         // noop
99 }
100
101     /**
102      * Does nothing.
103      */
104     public void nodeRemoved(Object JavaDoc nodeId) {
105         // noop
106 }
107
108     public void nodePropertyChanged(
109             Object JavaDoc nodeId,
110             String JavaDoc property,
111             Object JavaDoc oldValue,
112             Object JavaDoc newValue) {
113
114         Object JavaDoc node = graphMap.getNode(nodeId);
115         if (node != null) {
116             try {
117                 PropertyUtils.setSimpleProperty(node, property, newValue);
118             }
119             catch (Exception JavaDoc e) {
120                 throw new CayenneRuntimeException("Error setting property " + property, e);
121             }
122         }
123     }
124
125     public void arcCreated(Object JavaDoc nodeId, Object JavaDoc targetNodeId, Object JavaDoc arcId) {
126         Object JavaDoc node = graphMap.getNode(nodeId);
127         if (node != null) {
128
129             Object JavaDoc nodeTarget = graphMap.getNode(targetNodeId);
130
131             // treat arc id as a relationship name, and see if the property is a
132 // collection ... if it is add to collection, otherwise set directly
133 try {
134
135                 Object JavaDoc property = PropertyUtils.getSimpleProperty(node, arcId.toString());
136                 if (property instanceof Collection JavaDoc) {
137
138                     Collection JavaDoc collection = (Collection JavaDoc) property;
139                     if (nodeTarget != null && !collection.contains(nodeTarget)) {
140                         collection.add(nodeTarget);
141                     }
142                 }
143                 else {
144                     PropertyUtils.setSimpleProperty(node, arcId.toString(), nodeTarget);
145                 }
146             }
147             catch (Exception JavaDoc e) {
148                 throw new CayenneRuntimeException("Error creating arc " + arcId, e);
149             }
150         }
151     }
152
153     public void arcDeleted(Object JavaDoc nodeId, Object JavaDoc targetNodeId, Object JavaDoc arcId) {
154         Object JavaDoc node = graphMap.getNode(nodeId);
155         if (node != null) {
156
157             Object JavaDoc nodeTarget = graphMap.getNode(targetNodeId);
158
159             // treat arc id as a relationship name, and see if the property is a
160 // collection ... if it is remove from collection, otherwise set to null
161 try {
162
163                 Object JavaDoc property = PropertyUtils.getSimpleProperty(node, arcId.toString());
164                 if (property instanceof Collection JavaDoc) {
165
166                     Collection JavaDoc collection = (Collection JavaDoc) property;
167                     if (nodeTarget != null) {
168                         collection.remove(nodeTarget);
169                     }
170                 }
171                 else {
172                     PropertyUtils.setSimpleProperty(node, arcId.toString(), null);
173                 }
174             }
175             catch (Exception JavaDoc e) {
176                 throw new CayenneRuntimeException("Error removing arc " + arcId, e);
177             }
178         }
179     }
180
181 }
182
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