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Java > Open Source Codes > de > laures > cewolf > taglib > util > KeyGenerator


1 /* ================================================================
2  * Cewolf : Chart enabling Web Objects Framework
3  * ================================================================
4  *
5  * Project Info: http://cewolf.sourceforge.net
6  * Project Lead: Guido Laures (guido@laures.de);
7  *
8  * (C) Copyright 2002, by Guido Laures
9  *
10  * This library is free software; you can redistribute it and/or modify it under the terms
11  * of the GNU Lesser General Public License as published by the Free Software Foundation;
12  * either version 2.1 of the License, or (at your option) any later version.
13  *
14  * This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
15  * without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
16  * See the GNU Lesser General Public License for more details.
17  *
18  * You should have received a copy of the GNU Lesser General Public License along with this
19  * library; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
20  * Boston, MA 02111-1307, USA.
21  */
22
23 package de.laures.cewolf.taglib.util;
24
25 import java.io.IOException JavaDoc;
26 import java.io.Serializable JavaDoc;
27 import java.rmi.MarshalledObject JavaDoc;
28
29 import org.apache.commons.logging.Log;
30 import org.apache.commons.logging.LogFactory;
31
32 /**
33  * @author Guido Laures
34  */
35 public abstract class KeyGenerator {
36     
37     private static final Log log = LogFactory.getLog(KeyGenerator.class);
38
39     private static class NoKeyException extends RuntimeException JavaDoc {
40         public NoKeyException(String JavaDoc msg){
41             super(msg);
42         }
43     }
44
45     public static int generateKey(Serializable JavaDoc obj) {
46         if (obj == null) {
47             NoKeyException ex = new NoKeyException("assertion failed: can not generate key for null,");
48             throw ex;
49         }
50         try {
51             MarshalledObject JavaDoc mo = new MarshalledObject JavaDoc(obj);
52             return mo.hashCode();
53         } catch (IOException JavaDoc ioex) {
54             log.error("IOException during key generation KeyGenerator.generateKey()", ioex);
55             throw new NoKeyException(obj + " is not serializable.");
56         }
57     }
58 }
59
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