1/*
2 * Copyright (c) 1999, 2006, 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
26package javax.management;
27
28
29import java.util.List;
30import 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 */
58public 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    private List<String> enabledTypes = new Vector<String>();
68
69
70    /**
71     * Invoked before sending the specified notification to the listener.
72     * <BR>This filter compares the type of the specified notification with each enabled type.
73     * If the notification type matches one of the enabled types,
74     * the notification should be sent to the listener and this method returns <CODE>true</CODE>.
75     *
76     * @param notification The notification to be sent.
77     * @return <CODE>true</CODE> if the notification should be sent to the listener, <CODE>false</CODE> otherwise.
78     */
79    public synchronized boolean isNotificationEnabled(Notification notification) {
80
81        String type = notification.getType();
82
83        if (type == null) {
84            return false;
85        }
86        try {
87            for (String prefix : enabledTypes) {
88                if (type.startsWith(prefix)) {
89                    return true;
90                }
91            }
92        } catch (java.lang.NullPointerException e) {
93            // Should never occurs...
94            return false;
95        }
96        return false;
97    }
98
99    /**
100     * Enables all the notifications the type of which starts with the specified prefix
101     * to be sent to the listener.
102     * <BR>If the specified prefix is already in the list of enabled notification types,
103     * this method has no effect.
104     * <P>
105     * Example:
106     * <BLOCKQUOTE>
107     * <PRE>
108     * // Enables all notifications the type of which starts with "my_example" to be sent.
109     * myFilter.enableType("my_example");
110     * // Enables all notifications the type of which is "my_example.my_type" to be sent.
111     * myFilter.enableType("my_example.my_type");
112     * </PRE>
113     * </BLOCKQUOTE>
114     *
115     * Note that:
116     * <BLOCKQUOTE><CODE>
117     * myFilter.enableType("my_example.*");
118     * </CODE></BLOCKQUOTE>
119     * will no match any notification type.
120     *
121     * @param prefix The prefix.
122     * @exception java.lang.IllegalArgumentException The prefix parameter is null.
123     */
124    public synchronized void enableType(String prefix)
125            throws IllegalArgumentException {
126
127        if (prefix == null) {
128            throw new IllegalArgumentException("The prefix cannot be null.");
129        }
130        if (!enabledTypes.contains(prefix)) {
131            enabledTypes.add(prefix);
132        }
133    }
134
135    /**
136     * Removes the given prefix from the prefix list.
137     * <BR>If the specified prefix is not in the list of enabled notification types,
138     * this method has no effect.
139     *
140     * @param prefix The prefix.
141     */
142    public synchronized void disableType(String prefix) {
143        enabledTypes.remove(prefix);
144    }
145
146    /**
147     * Disables all notification types.
148     */
149    public synchronized void disableAllTypes() {
150        enabledTypes.clear();
151    }
152
153
154    /**
155     * Gets all the enabled notification types for this filter.
156     *
157     * @return The list containing all the enabled notification types.
158     */
159    public synchronized Vector<String> getEnabledTypes() {
160        return (Vector<String>)enabledTypes;
161    }
162
163}
164