UpgradeableDataHashMap


1   /*************************************************************************
2    *                                                                       *
3    *  EJBCA: The OpenSource Certificate Authority                          *
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5    *  This software is free software; you can redistribute it and/or       *
6    *  modify it under the terms of the GNU Lesser General Public           *
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9    *                                                                       *
10   *  See terms of license at gnu.org.                                     *
11   *                                                                       *
12   *************************************************************************/
13   
14  package org.ejbca.core.model;
15  
16  import java.util.HashMap  ;
17  
18  
19  
20  /**
21   * UpgradeableDataHashMap is an class implementing the IUpgradeableData intended to be extended by
22   * classes saving it's data to a database in BLOB form.
23   *
24   * @version $Id: UpgradeableDataHashMap.java,v 1.4 2006/05/28 14:21:11 anatom Exp $
25   *
26   * @see org.ejbca.core.model.IUpgradeableData
27   */
28  public abstract class UpgradeableDataHashMap implements IUpgradeableData, java.io.Serializable   {
29      /**
30       * Determines if a de-serialized file is compatible with this class.
31       *
32       * Maintainers must change this value if and only if the new version
33       * of this class is not compatible with old versions. See Sun docs
34       * for <a HREF=http://java.sun.com/products/jdk/1.1/docs/guide
35       * /serialization/spec/version.doc.html> details. </a>
36       *
37       */
38      private static final long serialVersionUID = -1766329888474901945L;
39      
40      /**
41       * Creates a new UpgradeableDataHashMap object.
42       */
43      public UpgradeableDataHashMap() {
44          data = new HashMap  ();
45          data.put(VERSION, new Float  (getLatestVersion()));
46      }
47  
48      /**
49       * Should return a constant containing the latest available version of the class.
50       *
51       * @return DOCUMENT ME!
52       */
53      public abstract float getLatestVersion();
54  
55      /**
56       * Function returning the current version of the class data.
57       *
58       * @return DOCUMENT ME!
59       */
60      public float getVersion() {
61          return ((Float  ) data.get(VERSION)).floatValue();
62      }
63  
64      /**
65       * Function sending the data to be saved to the database.
66       *
67       * @return DOCUMENT ME!
68       */
69      public Object   saveData() {
70          return data;
71      }
72  
73      /**
74       * Function loading saved data into to data structure.
75       *
76       * @param data DOCUMENT ME!
77       */
78      public void loadData(Object   data) {
79          this.data = (HashMap  ) data;
80          
81          if(Float.compare(getLatestVersion(), getVersion()) > 0) {
82              upgrade();            
83          }
84      }
85  
86      /**
87       * Function that should handle the update if of the data in the class so it's up to date with
88       * the latest version. An update is only done when needed.
89       */
90      public abstract void upgrade();
91  
92      protected HashMap   data;
93      public static final String   VERSION = "version";
94  }
95
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