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Java > Open Source Codes > org > apache > tomcat > util > modeler > FixedNotificationFilter


1 /*
2  * Licensed to the Apache Software Foundation (ASF) under one or more
3  * contributor license agreements. See the NOTICE file distributed with
4  * this work for additional information regarding copyright ownership.
5  * The ASF licenses this file to You under the Apache License, Version 2.0
6  * (the "License"); you may not use this file except in compliance with
7  * the License. You may obtain a copy of the License at
8  *
9  * http://www.apache.org/licenses/LICENSE-2.0
10  *
11  * Unless required by applicable law or agreed to in writing, software
12  * distributed under the License is distributed on an "AS IS" BASIS,
13  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14  * See the License for the specific language governing permissions and
15  * limitations under the License.
16  */
17
18
19 package org.apache.tomcat.util.modeler;
20
21
22 import java.util.HashSet JavaDoc;
23
24 import javax.management.Notification JavaDoc;
25 import javax.management.NotificationFilter JavaDoc;
26
27
28 /**
29  * Special NotificationFilter that allows modeler to optimize its notifications.
30  *
31  * This class is immutable - after you construct it it'll filter based on
32  * a fixed set of notification names.
33  *
34  * The JMX specification requires the filters to be called before the
35  * notifications are sent. We can call this filter well in advance, when
36  * the listener is added. Based on the result we can maintain separate
37  * channels for each notification - and reduce the overhead.
38  *
39  * @author Costin Manolache
40  */
41 public class FixedNotificationFilter implements NotificationFilter JavaDoc {
42
43     /**
44      * The set of attribute names that are accepted by this filter. If this
45      * list is empty, all attribute names are accepted.
46      */
47     private HashSet JavaDoc names = new HashSet JavaDoc();
48     String JavaDoc namesA[]=null;
49
50     /**
51      * Construct a new filter that accepts only the specified notification
52      * names.
53      *
54      * @param names Names of the notification types
55      */
56     public FixedNotificationFilter(String JavaDoc names[]) {
57         super();
58     }
59
60     /**
61      * Return the set of names that are accepted by this filter. If this
62      * filter accepts all attribute names, a zero length array will be
63      * returned.
64      */
65     public String JavaDoc[] getNames() {
66         synchronized (names) {
67             return ((String JavaDoc[]) names.toArray(new String JavaDoc[names.size()]));
68         }
69     }
70
71
72     /**
73      * <p>Test whether notification enabled for this event.
74      * Return true if:</p>
75      * <ul>
76      * <li>Either the set of accepted names is empty (implying that all
77      * attribute names are of interest) or the set of accepted names
78      * includes the name of the attribute in this notification</li>
79      * </ul>
80      */
81     public boolean isNotificationEnabled(Notification JavaDoc notification) {
82
83         if (notification == null)
84             return (false);
85         synchronized (names) {
86             if (names.size() < 1)
87                 return (true);
88             else
89                 return (names.contains(notification.getType()));
90         }
91
92     }
93
94
95 }
96
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