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Java > Open Source Codes > org > apache > commons > modeler > BaseAttributeFilter


1 /*
2  * Copyright 1999,2004 The Apache Software Foundation.
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  * http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16
17
18 package org.apache.commons.modeler;
19
20
21 import java.util.HashSet JavaDoc;
22
23 import javax.management.AttributeChangeNotification JavaDoc;
24 import javax.management.Notification JavaDoc;
25 import javax.management.NotificationFilter JavaDoc;
26
27
28 /**
29  * <p>Implementation of <code>NotificationFilter</code> for attribute change
30  * notifications. This class is used by <code>BaseModelMBean</code> to
31  * construct attribute change notification event filters when a filter is not
32  * supplied by the application.</p>
33  *
34  * @author Craig R. McClanahan
35  * @version $Revision$ $Date: 2005-02-26 05:12:25 -0800 (Sat, 26 Feb 2005) $
36  */
37
38 public class BaseAttributeFilter implements NotificationFilter JavaDoc {
39
40
41     // ----------------------------------------------------------- Constructors
42
43
44     /**
45      * Construct a new filter that accepts only the specified attribute
46      * name.
47      *
48      * @param name Name of the attribute to be accepted by this filter, or
49      * <code>null</code> to accept all attribute names
50      */
51     public BaseAttributeFilter(String JavaDoc name) {
52
53         super();
54         if (name != null)
55             addAttribute(name);
56
57     }
58
59
60     // ----------------------------------------------------- Instance Variables
61
62
63     /**
64      * The set of attribute names that are accepted by this filter. If this
65      * list is empty, all attribute names are accepted.
66      */
67     private HashSet JavaDoc names = new HashSet JavaDoc();
68
69
70     // --------------------------------------------------------- Public Methods
71
72
73     /**
74      * Add a new attribute name to the set of names accepted by this filter.
75      *
76      * @param name Name of the attribute to be accepted
77      */
78     public void addAttribute(String JavaDoc name) {
79
80         synchronized (names) {
81             names.add(name);
82         }
83
84     }
85
86
87     /**
88      * Clear all accepted names from this filter, so that it will accept
89      * all attribute names.
90      */
91     public void clear() {
92
93         synchronized (names) {
94             names.clear();
95         }
96
97     }
98
99
100     /**
101      * Return the set of names that are accepted by this filter. If this
102      * filter accepts all attribute names, a zero length array will be
103      * returned.
104      */
105     public String JavaDoc[] getNames() {
106
107         synchronized (names) {
108             return ((String JavaDoc[]) names.toArray(new String JavaDoc[names.size()]));
109         }
110
111     }
112
113
114     /**
115      * <p>Test whether notification enabled for this event.
116      * Return true if:</p>
117      * <ul>
118      * <li>This is an attribute change notification</li>
119      * <li>Either the set of accepted names is empty (implying that all
120      * attribute names are of interest) or the set of accepted names
121      * includes the name of the attribute in this notification</li>
122      * </ul>
123      */
124     public boolean isNotificationEnabled(Notification JavaDoc notification) {
125
126         if (notification == null)
127             return (false);
128         if (!(notification instanceof AttributeChangeNotification JavaDoc))
129             return (false);
130         AttributeChangeNotification JavaDoc acn =
131             (AttributeChangeNotification JavaDoc) notification;
132         if (!AttributeChangeNotification.ATTRIBUTE_CHANGE.equals(acn.getType()))
133             return (false);
134         synchronized (names) {
135             if (names.size() < 1)
136                 return (true);
137             else
138                 return (names.contains(acn.getAttributeName()));
139         }
140
141     }
142
143
144     /**
145      * Remove an attribute name from the set of names accepted by this
146      * filter.
147      *
148      * @param name Name of the attribute to be removed
149      */
150     public void removeAttribute(String JavaDoc name) {
151
152         synchronized (names) {
153             names.remove(name);
154         }
155
156     }
157
158
159 }
160
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