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Java > Open Source Codes > ClientId


1 /*
2  * This file belongs to the XQuark distribution.
3  * Copyright (C) 2003 Universite de Versailles Saint-Quentin.
4  *
5  * This program is free software; you can redistribute it and/or
6  * modify it under the terms of the GNU Lesser General Public
7  * License as published by the Free Software Foundation; either
8  * version 2.1 of the License, or (at your option) any later version.
9  *
10  * This program is distributed in the hope that it will be useful,
11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13  * Lesser General Public License for more details.
14  *
15  * You should have received a copy of the GNU Lesser General Public
16  * License along with this program; if not, write to the Free Software
17  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307.
18  * You can also get it at http://www.gnu.org/licenses/lgpl.html
19  *
20  * For more information on this software, see http://www.xquark.org.
21  */
22
23 import org.xquark.mapping.*;
24 import java.sql.*;
25 import java.math.*;
26
27 /* SAMPLE NOTE:
28  *
29  * This example shows a generic method for primary/foreign key generation.
30  * This may not be the best method for your favourite database. For instance,
31  * with Oracle you may prefer using a sequence.
32  */
33
34 public class ClientId implements UserGenerator {
35
36     private static int counter = -1;
37
38     public String JavaDoc getXMLType() {
39         return "int";
40     }
41
42     public synchronized Object JavaDoc getValue(StorageContext context) {
43         if (counter < 0)
44             initCounter(context.getConnection());
45         return new BigDecimal(++counter);
46     }
47     
48     void initCounter(Connection connection) {
49         ResultSet rs = null;
50         Statement statement = null;
51         try {
52             statement = connection.createStatement();
53             rs = statement.executeQuery("select max(\"id\") from \"client\"");
54             Object JavaDoc result = null;
55             while (rs.next()) {
56                 counter = rs.getInt(1);
57             }
58         }
59         catch (Exception JavaDoc ex) {
60             ex.printStackTrace();
61         }
62         finally {
63             try {
64                 if (rs != null)
65                     rs.close();
66                 if (statement != null)
67                     statement.close();
68             }
69             catch (SQLException ex) {
70                 // no op
71 }
72         }
73     }
74 }
75
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