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1 /*
2 * Copyright (c) 2003 Scott Howlett & Paul Libbrecht.
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 *
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 *
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in
14 * the documentation and/or other materials provided with the
15 * distribution.
16 *
17 * 3. The end-user documentation included with the redistribution,
18 * if any, must include the following acknowledgment:
19 * "This product includes software developed by the Xwing
20 * Project ( http://xwing.sourceforge.net/ )."
21 * Alternately, this acknowledgment may appear in the software itself,
22 * if and wherever such third-party acknowledgments normally appear.
23 *
24 * 4. The name "Xwing" must not be used to endorse or promote products
25 * derived from this software without prior written permission. For
26 * written permission, please contact the project authors via
27 * the Xwing project site, http://xwing.sourceforge.net/ .
28 *
29 * 5. Products derived from this software may not be called "Xwing",
30 * nor may "Xwing" appear in their name, without prior written
31 * permission of the Xwing project.
32 *
33 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
34 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
35 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
36 * DISCLAIMED. IN NO EVENT SHALL THE XWING AUTHORS OR THE PROJECT
37 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
38 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
39 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
40 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
41 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
42 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
43 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
44 * SUCH DAMAGE.
45 *
46 * For more information on Xwing, please see
47 * < http://xwing.sourceforge.net/ >.
48 */
49
50 package net.sourceforge.xwing.dom;
51
52 import org.apache.commons.logging.LogFactory;
53 import org.w3c.dom.Node;
54 import org.w3c.dom.events.Event;
55 import org.w3c.dom.events.EventListener;
56 import org.w3c.dom.events.EventTarget;
57
58 public abstract class NodeListener {
59
60 private Node node;
61 private EventListener realHandler;
62 private EventListener handler;
63 private String eventType;
64
65 public NodeListener() {
66 this(null, "DOMSubtreeModified");
67 }
68
69 public NodeListener(Node node) {
70 this(node, "DOMSubtreeModified");
71 }
72
73 public NodeListener(String eventType) {
74 this(null, eventType);
75 }
76
77 public NodeListener(Node node, String eventType) {
78 this.eventType = eventType;
79 realHandler = new EventListener() {
80 public void handleEvent(Event evt) {
81 try {
82 nodeChanged(evt);
83 } catch (Exception exc) {
84 LogFactory.getLog(getClass()).error(
85 "Error in handleEvent",
86 exc);
87 }
88 }
89 };
90
91 handler = new WeakEventListener(realHandler);
92
93 this.node = node;
94
95 attachHandler();
96 }
97
98 public Node getNode() {
99 return node;
100 }
101
102 public void setNode(Node newNode) {
103 if (node != newNode) {
104 removeHandler();
105 node = newNode;
106 attachHandler();
107 nodeChanged(null);
108 }
109 }
110
111 protected abstract void nodeChanged(Event evt);
112
113 protected void finalize() throws Throwable {
114 removeHandler();
115 super.finalize();
116 }
117
118 private void attachHandler() {
119 if (node != null) {
120 EventTarget evt = (EventTarget) node;
121 evt.addEventListener(eventType, handler, false);
122 }
123 }
124
125 private void removeHandler() {
126 if (node != null) {
127 EventTarget evt = (EventTarget) node;
128 evt.removeEventListener(eventType, handler, false);
129 }
130 }
131 }
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