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1   /***
2    * Redistribution and use of this software and associated documentation
3    * ("Software"), with or without modification, are permitted provided
4    * that the following conditions are met:
5    *
6    * 1. Redistributions of source code must retain copyright
7    *    statements and notices.  Redistributions must also contain a
8    *    copy of this document.
9    *
10   * 2. Redistributions in binary form must reproduce the
11   *    above copyright notice, this list of conditions and the
12   *    following disclaimer in the documentation and/or other
13   *    materials provided with the distribution.
14   *
15   * 3. The name "Exolab" must not be used to endorse or promote
16   *    products derived from this Software without prior written
17   *    permission of Exoffice Technologies.  For written permission,
18   *    please contact info@exolab.org.
19   *
20   * 4. Products derived from this Software may not be called "Exolab"
21   *    nor may "Exolab" appear in their names without prior written
22   *    permission of Exoffice Technologies. Exolab is a registered
23   *    trademark of Exoffice Technologies.
24   *
25   * 5. Due credit should be given to the Exolab Project
26   *    (http://www.exolab.org/).
27   *
28   * THIS SOFTWARE IS PROVIDED BY EXOFFICE TECHNOLOGIES AND CONTRIBUTORS
29   * ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT
30   * NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
31   * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL
32   * EXOFFICE TECHNOLOGIES OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
33   * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
34   * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
35   * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
36   * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
37   * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
38   * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
39   * OF THE POSSIBILITY OF SUCH DAMAGE.
40   *
41   * Copyright 2000,2003 (C) Exoffice Technologies Inc. All Rights Reserved.
42   *
43   * $Id: Event.java,v 1.1 2004/11/26 01:50:41 tanderson Exp $
44   *
45   * Date         Author  Changes
46   * 07/27/00	    jima    Created
47   */
48  package org.exolab.jms.events;
49  
50  import java.io.Serializable;
51  
52  
53  /***
54   * This class specifies the object that is used by the {@link EventManager}.
55   * It defines the event type, the event listener and the callback object.
56   * <p>
57   * The event type is an integral value that identifies the type of event to
58   * fire. It is transparent to the {@link EventManager}.
59   * <p>
60   * The event listener must implement the {@link EventHandler} interface.
61   * <p>
62   * The callback object must be {@link Serializable} and is passed back to the
63   * {@link EventHandler} when the event fires.
64   * <p>
65   * Most importantly this class is {@link Serializable} so that it can be
66   * stored, if required.
67   *
68   * @version     $Revision: 1.1 $ $Date: 2004/11/26 01:50:41 $
69   * @author      <a href="mailto:jima@intalio.com">Jim Alateras</a>
70   */
71  public class Event
72      implements Serializable {
73  
74      /***
75       * The event type.
76       */
77      private int _eventType;
78  
79      /***
80       * The _eventHandler is the object that is notified when the event fires.
81       * It must be Serializable so that it can be persisted.
82       */
83      private EventHandler _eventHandler = null;
84  
85      /***
86       * The _callbackObject is optionally specified and is passed back to the
87       * _eventHandler during notification.
88       */
89      private Object _callbackObject = null;
90  
91  
92      /***
93       * The constructor instantiates an instance of this class with the
94       * specified parameters. The event and listener must be non-null and
95       * valid but the callback object may be null.
96       *
97       * @param       event           the type of event to fire
98       * @param       listener        the object that will receive the event
99       * @param       callback        a callback object, that is Serializable
100      * @throws      IllegalEventDefinedException
101      */
102     public Event(int event, EventHandler listener, Object callback)
103         throws IllegalEventDefinedException {
104         if ((event != 0) &&
105             (listener != null)) {
106             _eventType = event;
107             _eventHandler = listener;
108 
109             // if the callback object has been specified then ensure that
110             // it is Serializabe. If the object isnot Serializable then throw
111             // an exception.
112             if (callback != null) {
113                 if (callback instanceof Serializable) {
114                     _callbackObject = callback;
115                 } else {
116                     throw new IllegalEventDefinedException(
117                         "The callback object is not Serializable");
118                 }
119             }
120         } else {
121             // event not-well specified
122             throw new IllegalEventDefinedException(
123                 "event is 0 or listener is null");
124         }
125     }
126 
127     /***
128      * Return the event type.
129      *
130      * @return      int
131      */
132     public int getEventType() {
133         return _eventType;
134     }
135 
136     /***
137      * Return the event listener
138      *
139      * @return      EventHandler
140      */
141     public EventHandler getEventListener() {
142         return _eventHandler;
143     }
144 
145     /***
146      * Return a reference to the callbacl object. The returned object may be
147      * null
148      *
149      * @return      Object
150      */
151     public Object getCallbackObject() {
152         return _callbackObject;
153     }
154 }
155 
156