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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 2000-2005 (C) Exoffice Technologies Inc. All Rights Reserved.
42   */
43  package org.exolab.jms.messagemgr;
44  
45  
46  import java.util.Comparator;
47  
48  
49  /***
50   * MessageHandleComparator is used to order messages on priority, acceptance
51   * time and sequence number.
52   *
53   * @version     $Revision: 1.2 $ $Date: 2005/03/18 03:58:39 $
54   * @author      <a href="mailto:jimm@intalio.com">Jim Mourikis</a>
55   */
56  public class MessageHandleComparator
57      implements Comparator {
58  
59      // implementation of Comparator.compare
60      public int compare(Object o1, Object o2) {
61  
62          int result = -1;
63  
64          // The order is on priority-acceptance time-sequence number
65          if ((o1 instanceof MessageHandle) &&
66              (o2 instanceof MessageHandle)) {
67              MessageHandle m1 = (MessageHandle) o1;
68              MessageHandle m2 = (MessageHandle) o2;
69  
70              if (m1.getPriority() == m2.getPriority()) {
71                  if (m1.getAcceptedTime() == m2.getAcceptedTime()) {
72                      if (m1.getSequenceNumber() == m2.getSequenceNumber()) {
73                          result = 0;
74                      } else if (m1.getSequenceNumber() > m2.getSequenceNumber()) {
75                          result = 1;
76                      } else {
77                          result = -1;
78                      }
79                  } else if (m1.getAcceptedTime() > m2.getAcceptedTime()) {
80                      result = 1;
81                  } else {
82                      result = -1;
83                  }
84              } else if (m1.getPriority() > m2.getPriority()) {
85                  result = -1;
86              } else {
87                  result = 1;
88              }
89          }
90  
91          return result;
92      }
93  
94      // implementation of Comparator.equals
95      public boolean equals(Object obj) {
96  
97          if (obj instanceof MessageHandleComparator) {
98              return true;
99          } else {
100             return false;
101         }
102     }
103 }
104