KickJava   Java API By Example, From Geeks To Geeks.

Java > Open Source Codes > org > objectstyle > cayenne > dba > DbAdapterDetector


1 /* ====================================================================
2  *
3  * The ObjectStyle Group Software License, version 1.1
4  * ObjectStyle Group - http://objectstyle.org/
5  *
6  * Copyright (c) 2002-2005, Andrei (Andrus) Adamchik and individual authors
7  * of the software. All rights reserved.
8  *
9  * Redistribution and use in source and binary forms, with or without
10  * modification, are permitted provided that the following conditions
11  * are met:
12  *
13  * 1. Redistributions of source code must retain the above copyright
14  * notice, this list of conditions and the following disclaimer.
15  *
16  * 2. Redistributions in binary form must reproduce the above copyright
17  * notice, this list of conditions and the following disclaimer in
18  * the documentation and/or other materials provided with the
19  * distribution.
20  *
21  * 3. The end-user documentation included with the redistribution, if any,
22  * must include the following acknowlegement:
23  * "This product includes software developed by independent contributors
24  * and hosted on ObjectStyle Group web site (http://objectstyle.org/)."
25  * Alternately, this acknowlegement may appear in the software itself,
26  * if and wherever such third-party acknowlegements normally appear.
27  *
28  * 4. The names "ObjectStyle Group" and "Cayenne" must not be used to endorse
29  * or promote products derived from this software without prior written
30  * permission. For written permission, email
31  * "andrus at objectstyle dot org".
32  *
33  * 5. Products derived from this software may not be called "ObjectStyle"
34  * or "Cayenne", nor may "ObjectStyle" or "Cayenne" appear in their
35  * names without prior written permission.
36  *
37  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
38  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
39  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
40  * DISCLAIMED. IN NO EVENT SHALL THE OBJECTSTYLE GROUP OR
41  * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
42  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
43  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
44  * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
45  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
46  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
47  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
48  * SUCH DAMAGE.
49  * ====================================================================
50  *
51  * This software consists of voluntary contributions made by many
52  * individuals and hosted on ObjectStyle Group web site. For more
53  * information on the ObjectStyle Group, please see
54  * <http://objectstyle.org/>.
55  */
56 package org.objectstyle.cayenne.dba;
57
58 import java.sql.Connection JavaDoc;
59 import java.sql.DatabaseMetaData JavaDoc;
60 import java.sql.SQLException JavaDoc;
61 import java.util.ArrayList JavaDoc;
62 import java.util.List JavaDoc;
63
64 import javax.sql.DataSource JavaDoc;
65
66 import org.apache.log4j.Logger;
67 import org.objectstyle.cayenne.dba.db2.DB2Sniffer;
68 import org.objectstyle.cayenne.dba.hsqldb.HSQLDBSniffer;
69 import org.objectstyle.cayenne.dba.mysql.MySQLSniffer;
70 import org.objectstyle.cayenne.dba.openbase.OpenBaseSniffer;
71 import org.objectstyle.cayenne.dba.oracle.OracleSniffer;
72 import org.objectstyle.cayenne.dba.postgres.PostgresSniffer;
73 import org.objectstyle.cayenne.dba.sqlserver.SQLServerSniffer;
74 import org.objectstyle.cayenne.dba.sybase.SybaseSniffer;
75
76 /**
77  * Guesses correct DbAdapter for an unknown database. This implementation obtains
78  * DatabaseMetaData object from the DataSource and passes it to a chain of conditional
79  * factories. The first DbAdapterFactory in the chain that "recognizes" the database would
80  * instantiate a DbAdapter that is returned to the user.
81  *
82  * @since 1.2
83  * @author Andrei Adamchik
84  */
85 // TODO: how can custom adapters be autodetected? I.e. is there a way to plug a
86 // custom factory into configuration loading process?
87 public class DbAdapterDetector {
88
89     private static Logger logObj = Logger.getLogger(DbAdapterDetector.class);
90
91     protected List JavaDoc factories;
92
93     public DbAdapterDetector() {
94         this.factories = new ArrayList JavaDoc();
95
96         // configure known predicates
97 addFactory(new MySQLSniffer());
98         addFactory(new PostgresSniffer());
99         addFactory(new OracleSniffer());
100         addFactory(new SQLServerSniffer());
101         addFactory(new HSQLDBSniffer());
102         addFactory(new DB2Sniffer());
103         addFactory(new SybaseSniffer());
104         addFactory(new OpenBaseSniffer());
105     }
106
107     /**
108      * Removes all configured factories.
109      */
110     public void clearFactories() {
111         this.factories.clear();
112     }
113
114     public void addFactory(DbAdapterFactory factory) {
115         this.factories.add(factory);
116     }
117
118     public DbAdapter adapterForDataSource(DataSource JavaDoc ds) throws SQLException JavaDoc {
119
120         Connection JavaDoc c = ds.getConnection();
121
122         // exclude opening connection from timing autodetection...
123 long t0 = System.currentTimeMillis();
124
125         try {
126             return adapterForMetaData(c.getMetaData());
127         }
128         finally {
129             try {
130                 c.close();
131             }
132             catch (SQLException JavaDoc e) {
133                 // ignore...
134 }
135
136             if (logObj.isInfoEnabled()) {
137                 long t1 = System.currentTimeMillis();
138                 logObj.info("auto-detection took " + (t1 - t0) + " ms.");
139             }
140         }
141     }
142
143     /**
144      * Returns a default adapter that is used as a failover if autodetection fails.
145      */
146     protected DbAdapter createDefaultAdapter() {
147         return new JdbcAdapter();
148     }
149
150     /**
151      * Iterates through predicated factories, stopping when the first one returns non-null
152      * DbAdapter. If none of the factories match the database, returns default adapter.
153      */
154     protected DbAdapter adapterForMetaData(DatabaseMetaData JavaDoc md) throws SQLException JavaDoc {
155
156         if (logObj.isInfoEnabled()) {
157             logObj.info("DB name: " + md.getDatabaseProductName());
158         }
159
160         // match against configured predicated factories
161
162         // iterate in reverse order to allow custom factories to take precedence over the
163 // default ones configured in constructor
164 for (int i = factories.size() - 1; i >= 0; i--) {
165             DbAdapterFactory factory = (DbAdapterFactory) factories.get(i);
166             DbAdapter adapter = factory.canHandleDatabase(md);
167
168             if (adapter != null) {
169                 return adapter;
170             }
171         }
172
173         logObj.info("Unrecognized database '"
174                 + md.getDatabaseProductName()
175                 + "', using default adapter.");
176
177         return createDefaultAdapter();
178     }
179 }
180
Popular Tags