1 /*
2 * $Source$
3 * $Revision$
4 *
5 * Copyright (C) 2000 David Warnock
6 *
7 * Part of Melati (http://melati.org), a framework for the rapid
8 * development of clean, maintainable web applications.
9 *
10 * Melati is free software; Permission is granted to copy, distribute
11 * and/or modify this software under the terms either:
12 *
13 * a) the GNU General Public License as published by the Free Software
14 * Foundation; either version 2 of the License, or (at your option)
15 * any later version,
16 *
17 * or
18 *
19 * b) any version of the Melati Software License, as published
20 * at http://melati.org
21 *
22 * You should have received a copy of the GNU General Public License and
23 * the Melati Software License along with this program;
24 * if not, write to the Free Software Foundation, Inc.,
25 * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA to obtain the
26 * GNU General Public License and visit http://melati.org to obtain the
27 * Melati Software License.
28 *
29 * Feel free to contact the Developers of Melati (http://melati.org),
30 * if you would like to work out a different arrangement than the options
31 * outlined here. It is our intention to allow Melati to be used by as
32 * wide an audience as possible.
33 *
34 * This program is distributed in the hope that it will be useful,
35 * but WITHOUT ANY WARRANTY; without even the implied warranty of
36 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
37 * GNU General Public License for more details.
38 *
39 * Contact details for copyright holder:
40 *
41 * David Warnock (david At sundayta.co.uk)
42 * Sundayta Ltd
43 * International House,
44 * 174 Three Bridges Road,
45 * Crawley,
46 * West Sussex
47 * RH10 1LE, UK
48 *
49 */
50
51 package org.melati.poem.dbms;
52
53 import java.util.Hashtable;
54
55 import org.melati.poem.AppBugPoemException;
56
57 /**
58 * A factory class to create Dbms objects.
59 */
60 public final class DbmsFactory {
61
62 private static final Hashtable<String, Dbms> dbmsObjects = new Hashtable<String, Dbms>();
63
64 private DbmsFactory() {
65 }
66
67 /**
68 * Return a Dbms object given its class name as a String.
69 *
70 * @param dbmsClass
71 * the name of the dbms class
72 * @return a cached or newly created Dmbs object
73 */
74 public static Dbms getDbms(String dbmsClass) {
75 synchronized (dbmsObjects) {
76 Dbms dbms = (Dbms)dbmsObjects.get(dbmsClass);
77 if (dbms != null) {
78 return dbms;
79 }
80
81 try {
82 Object dbmsObject = Class.forName(dbmsClass).newInstance();
83
84 if (!(dbmsObject instanceof Dbms)) {
85 throw new ClassCastException("The .class=" + dbmsClass
86 + " entry named a class of type " + dbmsObject.getClass()
87 + ", " + "which is not an org.melati.poem.dbms.Dbms");
88 }
89 dbms = (Dbms)dbmsObject;
90 } catch (Exception e) {
91 throw new AppBugPoemException("Problem instantiating class "
92 + dbmsClass, e);
93 }
94 dbmsObjects.put(dbmsClass, dbms);
95 return dbms;
96 }
97 }
98 }