001 /* DriverManager.java -- Manage JDBC drivers
002 Copyright (C) 1999, 2000, 2001, 2003, 2004, 2006
003 Free Software Foundation, Inc.
004
005 This file is part of GNU Classpath.
006
007 GNU Classpath is free software; you can redistribute it and/or modify
008 it under the terms of the GNU General Public License as published by
009 the Free Software Foundation; either version 2, or (at your option)
010 any later version.
011
012 GNU Classpath is distributed in the hope that it will be useful, but
013 WITHOUT ANY WARRANTY; without even the implied warranty of
014 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
015 General Public License for more details.
016
017 You should have received a copy of the GNU General Public License
018 along with GNU Classpath; see the file COPYING. If not, write to the
019 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
020 02110-1301 USA.
021
022 Linking this library statically or dynamically with other modules is
023 making a combined work based on this library. Thus, the terms and
024 conditions of the GNU General Public License cover the whole
025 combination.
026
027 As a special exception, the copyright holders of this library give you
028 permission to link this library with independent modules to produce an
029 executable, regardless of the license terms of these independent
030 modules, and to copy and distribute the resulting executable under
031 terms of your choice, provided that you also meet, for each linked
032 independent module, the terms and conditions of the license of that
033 module. An independent module is a module which is not derived from
034 or based on this library. If you modify this library, you may extend
035 this exception to your version of the library, but you are not
036 obligated to do so. If you do not wish to do so, delete this
037 exception statement from your version. */
038
039 package java.sql;
040
041 import java.io.PrintStream;
042 import java.io.PrintWriter;
043 import java.util.Enumeration;
044 import java.util.Properties;
045 import java.util.StringTokenizer;
046 import java.util.Vector;
047
048 /**
049 * This class manages the JDBC drivers in the system. It maintains a
050 * registry of drivers and locates the appropriate driver to handle a
051 * JDBC database URL.
052 * <p>
053 * On startup, <code>DriverManager</code> loads all the managers specified
054 * by the system property <code>jdbc.drivers</code>. The value of this
055 * property should be a colon separated list of fully qualified driver
056 * class names. Additional drivers can be loaded at any time by
057 * simply loading the driver class with <code>class.forName(String)</code>.
058 * The driver should automatically register itself in a static
059 * initializer.
060 * <p>
061 * The methods in this class are all <code>static</code>. This class
062 * cannot be instantiated.
063 *
064 * @author Aaron M. Renn (arenn@urbanophile.com)
065 */
066 public class DriverManager
067 {
068 /**
069 * This is the log stream for JDBC drivers.
070 */
071 private static PrintStream log_stream;
072
073 /**
074 * This is the log writer for JDBC drivers.
075 */
076 private static PrintWriter log_writer;
077
078 /**
079 * This is the login timeout used by JDBC drivers.
080 */
081 private static int login_timeout;
082
083 /**
084 * This is the list of JDBC drivers that are loaded.
085 */
086 private static Vector drivers;
087 // Hmm, seems like we might want to do a Hashtable and lookup by something,
088 // but what would it be?
089
090 // Load all drivers on startup
091 static
092 {
093 drivers = new Vector();
094
095 String driver_string = System.getProperty("jdbc.drivers");
096 if (driver_string != null)
097 {
098 StringTokenizer st = new StringTokenizer(driver_string);
099 while (st.hasMoreTokens())
100 {
101 String driver_classname = st.nextToken();
102
103 try
104 {
105 Class.forName(driver_classname); // The driver registers itself
106 }
107 catch (Exception e)
108 {
109 // Ignore not founds
110 }
111 }
112 }
113
114 }
115
116 /** Can't be instantiated. */
117 private DriverManager()
118 {
119 }
120
121 /**
122 * This method returns the log writer being used by all JDBC drivers.
123 * This method should be used in place of the deprecated
124 * <code>getLogStream</code> method.
125 *
126 * @return The log writer in use by JDBC drivers.
127 */
128 public static PrintWriter getLogWriter()
129 {
130 return log_writer;
131 }
132
133 /**
134 * This method sets the log writer being used by JDBC drivers. This is a
135 * system-wide parameter that affects all drivers. Note that since there
136 * is no way to retrieve a <code>PrintStream</code> from a
137 * <code>PrintWriter</code>, this method cannot set the log stream in
138 * use by JDBC. Thus any older drivers may not see this setting.
139 *
140 * @param out The new log writer for JDBC.
141 */
142 public static void setLogWriter(PrintWriter out)
143 {
144 DriverManager.log_writer = out;
145 }
146
147 /**
148 * This method attempts to return a connection to the specified
149 * JDBC URL string using the specified connection properties.
150 *
151 * @param url The JDBC URL string to connect to.
152 * @param properties The connection properties.
153 *
154 * @return A <code>Connection</code> to that URL.
155 *
156 * @exception SQLException If an error occurs.
157 */
158 public static Connection getConnection(String url, Properties properties)
159 throws SQLException
160 {
161 Driver d = getDriver(url);
162 if (d == null)
163 throw new SQLException("Driver not found for URL: " + url);
164
165 return d.connect(url, properties);
166 }
167
168
169 /**
170 * This method attempts to return a connection to the specified
171 * JDBC URL string using the specified username and password.
172 *
173 * @param url The JDBC URL string to connect to.
174 * @param user The username to connect with.
175 * @param password The password to connect with.
176 * @return A <code>Connection</code> to that URL.
177 * @exception SQLException If an error occurs.
178 */
179 public static Connection getConnection(String url, String user,
180 String password) throws SQLException
181 {
182 Properties p = new Properties();
183
184 if (user != null)
185 p.setProperty("user", user);
186 if (password != null)
187 p.setProperty("password", password);
188
189 return getConnection(url, p);
190 }
191
192 /**
193 * This method attempts to return a connection to the specified
194 * JDBC URL string.
195 *
196 * @param url The JDBC URL string to connect to.
197 *
198 * @return A <code>Connection</code> to that URL.
199 *
200 * @exception SQLException If an error occurs.
201 */
202 public static Connection getConnection(String url) throws SQLException
203 {
204 return getConnection(url, new Properties());
205 }
206
207 /**
208 * This method returns a driver that can connect to the specified
209 * JDBC URL string. This will be selected from among drivers loaded
210 * at initialization time and those drivers manually loaded by the
211 * same class loader as the caller.
212 *
213 * @param url The JDBC URL string to find a driver for.
214 *
215 * @return A <code>Driver</code> that can connect to the specified
216 * URL.
217 *
218 * @exception SQLException If an error occurs, or no suitable driver can be found.
219 */
220 public static Driver getDriver(String url) throws SQLException
221 {
222 // FIXME: Limit driver search to the appropriate subset of loaded drivers.
223 Enumeration e = drivers.elements();
224 while(e.hasMoreElements())
225 {
226 Driver d = (Driver)e.nextElement();
227 if (d.acceptsURL(url))
228 return d;
229 }
230
231 throw new SQLException("No driver found for " + url);
232 }
233
234 /**
235 * This method registers a new driver with the manager. This is normally
236 * called by the driver itself in a static initializer.
237 *
238 * @param driver The new <code>Driver</code> to add.
239 *
240 * @exception SQLException If an error occurs.
241 */
242 public static void registerDriver(Driver driver) throws SQLException
243 {
244 if (! drivers.contains(driver))
245 drivers.addElement(driver);
246 }
247
248 /**
249 * This method de-registers a driver from the manager.
250 *
251 * @param driver The <code>Driver</code> to unregister.
252 *
253 * @exception SQLException If an error occurs.
254 */
255 public static void deregisterDriver(Driver driver) throws SQLException
256 {
257 if (drivers.contains(driver))
258 drivers.removeElement(driver);
259 }
260
261 /**
262 * This method returns a list of all the currently registered JDBC drivers
263 * that were loaded by the current <code>ClassLoader</code>.
264 *
265 * @return An <code>Enumeration</code> of all currently loaded JDBC drivers.
266 */
267 public static Enumeration<Driver> getDrivers()
268 {
269 Vector v = new Vector();
270 Enumeration e = drivers.elements();
271
272 // Is this right?
273 ClassLoader cl = Thread.currentThread().getContextClassLoader();
274
275 while(e.hasMoreElements())
276 {
277 Object obj = e.nextElement();
278
279 ClassLoader loader = obj.getClass().getClassLoader();
280
281 if (loader == null)
282 loader = ClassLoader.getSystemClassLoader();
283 if (! loader.equals(cl))
284 continue;
285
286 v.addElement(obj);
287 }
288
289 return v.elements();
290 }
291
292 /**
293 * This method set the login timeout used by JDBC drivers. This is a
294 * system-wide parameter that applies to all drivers.
295 *
296 * @param seconds The new login timeout value.
297 */
298 public static void setLoginTimeout(int seconds)
299 {
300 DriverManager.login_timeout = seconds;
301 }
302
303 /**
304 * This method returns the login timeout in use by JDBC drivers systemwide.
305 *
306 * @return The login timeout.
307 */
308 public static int getLoginTimeout()
309 {
310 return login_timeout;
311 }
312
313 /**
314 * This method sets the log stream in use by JDBC.
315 *
316 * @param stream The log stream in use by JDBC.
317 * @deprecated Use <code>setLogWriter</code> instead.
318 */
319 public static void setLogStream(PrintStream stream)
320 {
321 DriverManager.log_stream = stream;
322 }
323
324 /**
325 * This method returns the log stream in use by JDBC.
326 *
327 * @return The log stream in use by JDBC.
328 * @deprecated Use <code>getLogWriter()</code> instead.
329 */
330 public static PrintStream getLogStream()
331 {
332 return log_stream;
333 }
334
335 /**
336 * This method prints the specified line to the log stream.
337 *
338 * @param message The string to write to the log stream.
339 */
340 public static void println(String message)
341 {
342 if (log_stream != null) // Watch for user not using logging
343 log_stream.println(message);
344 }
345 }