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Java > Open Source Codes > org > exolab > jms > message > MessageId


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 2000-2004 (C) Exoffice Technologies Inc. All Rights Reserved.
42  *
43  * $Id: MessageId.java,v 1.1 2004/11/26 01:50:43 tanderson Exp $
44  */
45 package org.exolab.jms.message;
46
47 import java.io.Externalizable JavaDoc;
48 import java.io.IOException JavaDoc;
49 import java.io.ObjectInput JavaDoc;
50 import java.io.ObjectOutput JavaDoc;
51
52 import org.exolab.jms.common.uuid.UUID;
53
54
55 /**
56  * The MessageId is a serializable object that uniquely identifies a message
57  *
58  * @version $Revision: 1.1 $ $Date: 2004/11/26 01:50:43 $
59  * @author <a HREF="mailto:jima@comware.com.au">Jim Alateras</a>
60  */
61 final public class MessageId
62         implements Externalizable JavaDoc {
63
64     /**
65      * Version Id used for streaming
66      */
67     static final long serialVersionUID = 2;
68
69     /**
70      * The JMS message identifier
71      */
72     private String JavaDoc _id = null;
73
74     /**
75      * The JMS message identifier prefix
76      */
77     public final static String JavaDoc PREFIX = "ID:";
78
79     /**
80      * A null object identity
81      */
82     private static final String JavaDoc NULL_ID = "ID:0";
83
84
85     /**
86      * Constructor provided for serialization
87      */
88     public MessageId() {
89     }
90
91     /**
92      * Construct a new <code>MessageId</code>
93      *
94      * @param id - the message identity
95      */
96     public MessageId(String JavaDoc id) {
97         _id = id;
98     }
99
100     public String JavaDoc getId() {
101         return _id;
102     }
103
104     // implementation of Object.hashCode
105 public int hashCode() {
106         return _id.hashCode();
107     }
108
109     // implementation of Externalizable.writeExternal
110 public void writeExternal(ObjectOutput JavaDoc out) throws IOException JavaDoc {
111         out.writeLong(serialVersionUID);
112         out.writeUTF(_id);
113     }
114
115     // implementation of Externalizable.readExternal
116 public void readExternal(ObjectInput JavaDoc in)
117             throws IOException JavaDoc, ClassNotFoundException JavaDoc {
118
119         // read the serial number of the object and ensure that
120 // we can process it.
121 long version = in.readLong();
122         if (version == serialVersionUID) {
123             _id = in.readUTF();
124         } else if (version == 1) {
125             // for backwards compatibility
126 long oldID = in.readLong(); // discard this
127 String JavaDoc id = (String JavaDoc) in.readObject();
128             _id = PREFIX + id;
129         } else {
130             throw new IOException JavaDoc("Incorrect version enountered: " +
131                                   version + " This version = " +
132                                   serialVersionUID);
133         }
134     }
135
136     // override Object.toString
137 public String JavaDoc toString() {
138         return _id;
139     }
140
141     // override Object,equals
142 public boolean equals(Object JavaDoc object) {
143         boolean equal = (object == this);
144         if (!equal) {
145             if (object instanceof MessageId &&
146                     ((MessageId) object)._id.equals(_id)) {
147                 equal = true;
148             }
149         }
150
151         return equal;
152     }
153
154     /**
155      * Allocate a new globally unique message identifier
156      *
157      * @return a globally unique message identifier
158      */
159     public static String JavaDoc create() {
160         return UUID.next(PREFIX);
161     }
162
163     /**
164      * Return the 'null' JMSMessageID.
165      * This is the first Id recognised by OpenJMS, but not assigned
166      * to messages.
167      *
168      * @return String the 'null' message Id
169      */
170     public static String JavaDoc getNull() {
171         return NULL_ID;
172     }
173
174 }
175
176
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