1 /*
2 * Copyright (c) 1999, 2019, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package javax.management;
27
28
29 import java.util.List;
30 import java.util.Vector;
31
32 /**
33 * Provides an implementation of the {@link javax.management.NotificationFilter} interface.
34 * The filtering is performed on the notification type attribute.
35 * <P>
36 * Manages a list of enabled notification types.
37 * A method allows users to enable/disable as many notification types as required.
38 * <P>
39 * Then, before sending a notification to a listener registered with a filter,
40 * the notification broadcaster compares this notification type with all notification types
41 * enabled by the filter. The notification will be sent to the listener
42 * only if its filter enables this notification type.
43 * <P>
44 * Example:
45 * <BLOCKQUOTE>
46 * <PRE>
47 * NotificationFilterSupport myFilter = new NotificationFilterSupport();
48 * myFilter.enableType("my_example.my_type");
49 * myBroadcaster.addListener(myListener, myFilter, null);
50 * </PRE>
51 * </BLOCKQUOTE>
52 * The listener <CODE>myListener</CODE> will only receive notifications the type of which equals/starts with "my_example.my_type".
53 *
54 * @see javax.management.NotificationBroadcaster#addNotificationListener
55 *
56 * @since 1.5
57 */
58 public class NotificationFilterSupport implements NotificationFilter {
59
60 /* Serial version */
61 private static final long serialVersionUID = 6579080007561786969L;
62
63 /**
64 * @serial {@link Vector} that contains the enabled notification types.
65 * The default value is an empty vector.
66 */
67 @SuppressWarnings("serial") // Not statically typed as Serializable
68 private List<String> enabledTypes = new Vector<String>();
69
70
71 /**
72 * Invoked before sending the specified notification to the listener.
73 * <BR>This filter compares the type of the specified notification with each enabled type.
74 * If the notification type matches one of the enabled types,
75 * the notification should be sent to the listener and this method returns <CODE>true</CODE>.
76 *
77 * @param notification The notification to be sent.
78 * @return <CODE>true</CODE> if the notification should be sent to the listener, <CODE>false</CODE> otherwise.
79 */
80 public synchronized boolean isNotificationEnabled(Notification notification) {
81
82 String type = notification.getType();
83
84 if (type == null) {
85 return false;
86 }
87 try {
88 for (String prefix : enabledTypes) {
89 if (type.startsWith(prefix)) {
90 return true;
91 }
92 }
93 } catch (java.lang.NullPointerException e) {
94 // Should never occurs...
95 return false;
96 }
97 return false;
98 }
99
100 /**
101 * Enables all the notifications the type of which starts with the specified prefix
102 * to be sent to the listener.
103 * <BR>If the specified prefix is already in the list of enabled notification types,
104 * this method has no effect.
105 * <P>
106 * Example:
107 * <BLOCKQUOTE>
108 * <PRE>
109 * // Enables all notifications the type of which starts with "my_example" to be sent.
110 * myFilter.enableType("my_example");
111 * // Enables all notifications the type of which is "my_example.my_type" to be sent.
112 * myFilter.enableType("my_example.my_type");
113 * </PRE>
114 * </BLOCKQUOTE>
115 *
116 * Note that:
117 * <BLOCKQUOTE><CODE>
118 * myFilter.enableType("my_example.*");
119 * </CODE></BLOCKQUOTE>
120 * will no match any notification type.
121 *
122 * @param prefix The prefix.
123 * @exception java.lang.IllegalArgumentException The prefix parameter is null.
124 */
125 public synchronized void enableType(String prefix)
126 throws IllegalArgumentException {
127
128 if (prefix == null) {
129 throw new IllegalArgumentException("The prefix cannot be null.");
130 }
131 if (!enabledTypes.contains(prefix)) {
132 enabledTypes.add(prefix);
133 }
134 }
135
136 /**
137 * Removes the given prefix from the prefix list.
138 * <BR>If the specified prefix is not in the list of enabled notification types,
139 * this method has no effect.
140 *
141 * @param prefix The prefix.
142 */
143 public synchronized void disableType(String prefix) {
144 enabledTypes.remove(prefix);
145 }
146
147 /**
148 * Disables all notification types.
149 */
150 public synchronized void disableAllTypes() {
151 enabledTypes.clear();
152 }
153
154
155 /**
156 * Gets all the enabled notification types for this filter.
157 *
158 * @return The list containing all the enabled notification types.
159 */
160 public synchronized Vector<String> getEnabledTypes() {
161 return (Vector<String>)enabledTypes;
162 }
163
164 }