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


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.Notification JavaDoc;
24 import javax.management.NotificationFilter JavaDoc;
25
26
27 /**
28  * Special NotificationFilter that allows modeler to optimize its notifications.
29  *
30  * This class is immutable - after you construct it it'll filter based on
31  * a fixed set of notification names.
32  *
33  * The JMX specification requires the filters to be called before the
34  * notifications are sent. We can call this filter well in advance, when
35  * the listener is added. Based on the result we can maintain separate
36  * channels for each notification - and reduce the overhead.
37  *
38  * @author Costin Manolache
39  */
40 public class FixedNotificationFilter implements NotificationFilter JavaDoc {
41
42     /**
43      * The set of attribute names that are accepted by this filter. If this
44      * list is empty, all attribute names are accepted.
45      */
46     private HashSet JavaDoc names = new HashSet JavaDoc();
47     String JavaDoc namesA[]=null;
48
49     /**
50      * Construct a new filter that accepts only the specified notification
51      * names.
52      *
53      * @param names Names of the notification types
54      */
55     public FixedNotificationFilter(String JavaDoc names[]) {
56         super();
57     }
58
59     /**
60      * Return the set of names that are accepted by this filter. If this
61      * filter accepts all attribute names, a zero length array will be
62      * returned.
63      */
64     public String JavaDoc[] getNames() {
65         synchronized (names) {
66             return ((String JavaDoc[]) names.toArray(new String JavaDoc[names.size()]));
67         }
68     }
69
70
71     /**
72      * <p>Test whether notification enabled for this event.
73      * Return true if:</p>
74      * <ul>
75      * <li>Either the set of accepted names is empty (implying that all
76      * attribute names are of interest) or the set of accepted names
77      * includes the name of the attribute in this notification</li>
78      * </ul>
79      */
80     public boolean isNotificationEnabled(Notification JavaDoc notification) {
81
82         if (notification == null)
83             return (false);
84         synchronized (names) {
85             if (names.size() < 1)
86                 return (true);
87             else
88                 return (names.contains(notification.getType()));
89         }
90
91     }
92
93
94 }
95
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