1 /**
2 * Copyright (c) 2004-2011 QOS.ch
3 * All rights reserved.
4 *
5 * Permission is hereby granted, free of charge, to any person obtaining
6 * a copy of this software and associated documentation files (the
7 * "Software"), to deal in the Software without restriction, including
8 * without limitation the rights to use, copy, modify, merge, publish,
9 * distribute, sublicense, and/or sell copies of the Software, and to
10 * permit persons to whom the Software is furnished to do so, subject to
11 * the following conditions:
12 *
13 * The above copyright notice and this permission notice shall be
14 * included in all copies or substantial portions of the Software.
15 *
16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
17 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
18 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
19 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
20 * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
21 * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
22 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
23 *
24 */
25 package org.slf4j.bridge;
26
27 import java.text.MessageFormat;
28 import java.util.MissingResourceException;
29 import java.util.ResourceBundle;
30 import java.util.logging.Handler;
31 import java.util.logging.Level;
32 import java.util.logging.LogManager;
33 import java.util.logging.LogRecord;
34
35 import org.slf4j.Logger;
36 import org.slf4j.LoggerFactory;
37 import org.slf4j.spi.LocationAwareLogger;
38
39 // Based on http://bugzilla.slf4j.org/show_bug.cgi?id=38
40
41 /**
42 * <p>Bridge/route all JUL log records to the SLF4J API.</p>
43 * <p>Essentially, the idea is to install on the root logger an instance of
44 * <code>SLF4JBridgeHandler</code> as the sole JUL handler in the system. Subsequently, the
45 * SLF4JBridgeHandler instance will redirect all JUL log records are redirected
46 * to the SLF4J API based on the following mapping of levels:
47 * </p>
48 * <pre>
49 * FINEST -> TRACE
50 * FINER -> DEBUG
51 * FINE -> DEBUG
52 * INFO -> INFO
53 * WARNING -> WARN
54 * SEVERE -> ERROR</pre>
55 * <p><b>Programmatic installation:</b></p>
56 * <pre>
57 * // Optionally remove existing handlers attached to j.u.l root logger
58 * SLF4JBridgeHandler.removeHandlersForRootLogger(); // (since SLF4J 1.6.5)
59
60 * // add SLF4JBridgeHandler to j.u.l's root logger, should be done once during
61 * // the initialization phase of your application
62 * SLF4JBridgeHandler.install();</pre>
63 * <p><b>Installation via <em>logging.properties</em> configuration file:</b></p>
64 * <pre>
65 * // register SLF4JBridgeHandler as handler for the j.u.l. root logger
66 * handlers = org.slf4j.bridge.SLF4JBridgeHandler</pre>
67 * <p>Once SLF4JBridgeHandler is installed, logging by j.u.l. loggers will be directed to
68 * SLF4J. Example: </p>
69 * <pre>
70 * import java.util.logging.Logger;
71 * ...
72 * // usual pattern: get a Logger and then log a message
73 * Logger julLogger = Logger.getLogger("org.wombat");
74 * julLogger.fine("hello world"); // this will get redirected to SLF4J</pre>
75 *
76 * <p>Please note that translating a java.util.logging event into SLF4J incurs the
77 * cost of constructing {@link LogRecord} instance regardless of whether the
78 * SLF4J logger is disabled for the given level. <b>Consequently, j.u.l. to
79 * SLF4J translation can seriously increase the cost of disabled logging
80 * statements (60 fold or 6000% increase) and measurably impact the performance of enabled log
81 * statements (20% overall increase).</b> Please note that as of logback-version 0.9.25,
82 * it is possible to completely eliminate the 60 fold translation overhead for disabled
83 * log statements with the help of <a href="http://logback.qos.ch/manual/configuration.html#LevelChangePropagator">LevelChangePropagator</a>.
84 * </p>
85 *
86 * <p>If you are concerned about application performance, then use of <code>SLF4JBridgeHandler</code>
87 * is appropriate only if any one the following two conditions is true:</p>
88 * <ol>
89 * <li>few j.u.l. logging statements are in play</li>
90 * <li>LevelChangePropagator has been installed</li>
91 * </ol>
92 *
93 * @author Christian Stein
94 * @author Joern Huxhorn
95 * @author Ceki Gülcü
96 * @author Darryl Smith
97 * @since 1.5.1
98 */
99 public class SLF4JBridgeHandler extends Handler {
100
101 // The caller is java.util.logging.Logger
102 private static final String FQCN = java.util.logging.Logger.class.getName();
103 private static final String UNKNOWN_LOGGER_NAME = "unknown.jul.logger";
104
105 private static final int TRACE_LEVEL_THRESHOLD = Level.FINEST.intValue();
106 private static final int DEBUG_LEVEL_THRESHOLD = Level.FINE.intValue();
107 private static final int INFO_LEVEL_THRESHOLD = Level.INFO.intValue();
108 private static final int WARN_LEVEL_THRESHOLD = Level.WARNING.intValue();
109
110 /**
111 * Adds a SLF4JBridgeHandler instance to jul's root logger.
112 * <p/>
113 * <p/>
114 * This handler will redirect j.u.l. logging to SLF4J. However, only logs enabled
115 * in j.u.l. will be redirected. For example, if a log statement invoking a
116 * j.u.l. logger is disabled, then the corresponding non-event will <em>not</em>
117 * reach SLF4JBridgeHandler and cannot be redirected.
118 */
119 public static void install() {
120 LogManager.getLogManager().getLogger("").addHandler(
121 new SLF4JBridgeHandler());
122 }
123
124 private static java.util.logging.Logger getRootLogger() {
125 return LogManager.getLogManager().getLogger("");
126 }
127
128 /**
129 * Removes previously installed SLF4JBridgeHandler instances. See also
130 * {@link #install()}.
131 *
132 * @throws SecurityException A <code>SecurityException</code> is thrown, if a security manager
133 * exists and if the caller does not have
134 * LoggingPermission("control").
135 */
136 public static void uninstall() throws SecurityException {
137 java.util.logging.Logger rootLogger = getRootLogger();
138 Handler[] handlers = rootLogger.getHandlers();
139 for (int i = 0; i < handlers.length; i++) {
140 if (handlers[i] instanceof SLF4JBridgeHandler) {
141 rootLogger.removeHandler(handlers[i]);
142 }
143 }
144 }
145
146 /**
147 * Returns true if SLF4JBridgeHandler has been previously installed, returns false otherwise.
148 *
149 * @return true if SLF4JBridgeHandler is already installed, false other wise
150 * @throws SecurityException
151 */
152 public static boolean isInstalled() throws SecurityException {
153 java.util.logging.Logger rootLogger = getRootLogger();
154 Handler[] handlers = rootLogger.getHandlers();
155 for (int i = 0; i < handlers.length; i++) {
156 if (handlers[i] instanceof SLF4JBridgeHandler) {
157 return true;
158 }
159 }
160 return false;
161 }
162
163 /**
164 * Invoking this method removes/unregisters/detaches all handlers currently attached to the root logger
165 * @since 1.6.5
166 */
167 public static void removeHandlersForRootLogger() {
168 java.util.logging.Logger rootLogger = getRootLogger();
169 java.util.logging.Handler[] handlers = rootLogger.getHandlers();
170 for (int i = 0; i < handlers.length; i++) {
171 rootLogger.removeHandler(handlers[i]);
172 }
173 }
174
175
176 /**
177 * Initialize this handler.
178 */
179 public SLF4JBridgeHandler() {
180 }
181
182 /**
183 * No-op implementation.
184 */
185 public void close() {
186 // empty
187 }
188
189 /**
190 * No-op implementation.
191 */
192 public void flush() {
193 // empty
194 }
195
196 /**
197 * Return the Logger instance that will be used for logging.
198 */
199 protected Logger getSLF4JLogger(LogRecord record) {
200 String name = record.getLoggerName();
201 if (name == null) {
202 name = UNKNOWN_LOGGER_NAME;
203 }
204 return LoggerFactory.getLogger(name);
205 }
206
207 protected void callLocationAwareLogger(LocationAwareLogger lal,
208 LogRecord record) {
209 int julLevelValue = record.getLevel().intValue();
210 int slf4jLevel;
211
212 if (julLevelValue <= TRACE_LEVEL_THRESHOLD) {
213 slf4jLevel = LocationAwareLogger.TRACE_INT;
214 } else if (julLevelValue <= DEBUG_LEVEL_THRESHOLD) {
215 slf4jLevel = LocationAwareLogger.DEBUG_INT;
216 } else if (julLevelValue <= INFO_LEVEL_THRESHOLD) {
217 slf4jLevel = LocationAwareLogger.INFO_INT;
218 } else if (julLevelValue <= WARN_LEVEL_THRESHOLD) {
219 slf4jLevel = LocationAwareLogger.WARN_INT;
220 } else {
221 slf4jLevel = LocationAwareLogger.ERROR_INT;
222 }
223 String i18nMessage = getMessageI18N(record);
224 lal.log(null, FQCN, slf4jLevel, i18nMessage, null, record.getThrown());
225 }
226
227 protected void callPlainSLF4JLogger(Logger slf4jLogger, LogRecord record) {
228 String i18nMessage = getMessageI18N(record);
229 int julLevelValue = record.getLevel().intValue();
230 if (julLevelValue <= TRACE_LEVEL_THRESHOLD) {
231 slf4jLogger.trace(i18nMessage, record.getThrown());
232 } else if (julLevelValue <= DEBUG_LEVEL_THRESHOLD) {
233 slf4jLogger.debug(i18nMessage, record.getThrown());
234 } else if (julLevelValue <= INFO_LEVEL_THRESHOLD) {
235 slf4jLogger.info(i18nMessage, record.getThrown());
236 } else if (julLevelValue <= WARN_LEVEL_THRESHOLD) {
237 slf4jLogger.warn(i18nMessage, record.getThrown());
238 } else {
239 slf4jLogger.error(i18nMessage, record.getThrown());
240 }
241 }
242
243
244 /**
245 * Get the record's message, possibly via a resource bundle.
246 *
247 * @param record
248 * @return
249 */
250 private String getMessageI18N(LogRecord record) {
251 String message = record.getMessage();
252
253 if (message == null) {
254 return null;
255 }
256
257 ResourceBundle bundle = record.getResourceBundle();
258 if (bundle != null) {
259 try {
260 message = bundle.getString(message);
261 } catch (MissingResourceException e) {
262 }
263 }
264 Object[] params = record.getParameters();
265 // avoid formatting when there are no or 0 parameters. see also
266 // http://bugzilla.slf4j.org/show_bug.cgi?id=212
267 if (params != null && params.length > 0) {
268 message = MessageFormat.format(message, params);
269 }
270 return message;
271 }
272
273 /**
274 * Publish a LogRecord.
275 * <p/>
276 * The logging request was made initially to a Logger object, which
277 * initialized the LogRecord and forwarded it here.
278 * <p/>
279 * This handler ignores the Level attached to the LogRecord, as SLF4J cares
280 * about discarding log statements.
281 *
282 * @param record Description of the log event. A null record is silently ignored
283 * and is not published.
284 */
285 public void publish(LogRecord record) {
286 // Silently ignore null records.
287 if (record == null) {
288 return;
289 }
290
291 Logger slf4jLogger = getSLF4JLogger(record);
292 String message = record.getMessage(); // can be null!
293 // this is a check to avoid calling the underlying logging system
294 // with a null message. While it is legitimate to invoke j.u.l. with
295 // a null message, other logging frameworks do not support this.
296 // see also http://bugzilla.slf4j.org/show_bug.cgi?id=108
297 if (message == null) {
298 message = "";
299 }
300 if (slf4jLogger instanceof LocationAwareLogger) {
301 callLocationAwareLogger((LocationAwareLogger) slf4jLogger, record);
302 } else {
303 callPlainSLF4JLogger(slf4jLogger, record);
304 }
305 }
306
307 }