1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17
18 package org.apache.commons.logging.impl;
19
20 import java.io.Serializable;
21 import org.apache.commons.logging.Log;
22 import org.apache.log4j.Logger;
23 import org.apache.log4j.Priority;
24 import org.apache.log4j.Level;
25
26 /**
27 * Implementation of {@link Log} that maps directly to a
28 * <strong>Logger</strong> for log4J version 1.2.
29 * <p>
30 * Initial configuration of the corresponding Logger instances should be done
31 * in the usual manner, as outlined in the Log4J documentation.
32 * <p>
33 * The reason this logger is distinct from the 1.3 logger is that in version 1.2
34 * of Log4J:
35 * <ul>
36 * <li>class Logger takes Priority parameters not Level parameters.
37 * <li>class Level extends Priority
38 * </ul>
39 * Log4J1.3 is expected to change Level so it no longer extends Priority, which is
40 * a non-binary-compatible change. The class generated by compiling this code against
41 * log4j 1.2 will therefore not run against log4j 1.3.
42 *
43 * @version $Id: Log4JLogger.java 1448119 2013-02-20 12:28:04Z tn $
44 */
45 public class Log4JLogger implements Log, Serializable {
46
47 /** Serializable version identifier. */
48 private static final long serialVersionUID = 5160705895411730424L;
49
50 // ------------------------------------------------------------- Attributes
51
52 /** The fully qualified name of the Log4JLogger class. */
53 private static final String FQCN = Log4JLogger.class.getName();
54
55 /** Log to this logger */
56 private transient volatile Logger logger = null;
57
58 /** Logger name */
59 private final String name;
60
61 private static final Priority traceLevel;
62
63 // ------------------------------------------------------------
64 // Static Initializer.
65 //
66 // Note that this must come after the static variable declarations
67 // otherwise initialiser expressions associated with those variables
68 // will override any settings done here.
69 //
70 // Verify that log4j is available, and that it is version 1.2.
71 // If an ExceptionInInitializerError is generated, then LogFactoryImpl
72 // will treat that as meaning that the appropriate underlying logging
73 // library is just not present - if discovery is in progress then
74 // discovery will continue.
75 // ------------------------------------------------------------
76
77 static {
78 if (!Priority.class.isAssignableFrom(Level.class)) {
79 // nope, this is log4j 1.3, so force an ExceptionInInitializerError
80 throw new InstantiationError("Log4J 1.2 not available");
81 }
82
83 // Releases of log4j1.2 >= 1.2.12 have Priority.TRACE available, earlier
84 // versions do not. If TRACE is not available, then we have to map
85 // calls to Log.trace(...) onto the DEBUG level.
86
87 Priority _traceLevel;
88 try {
89 _traceLevel = (Priority) Level.class.getDeclaredField("TRACE").get(null);
90 } catch(Exception ex) {
91 // ok, trace not available
92 _traceLevel = Level.DEBUG;
93 }
94 traceLevel = _traceLevel;
95 }
96
97 // ------------------------------------------------------------ Constructor
98
99 public Log4JLogger() {
100 name = null;
101 }
102
103 /**
104 * Base constructor.
105 */
106 public Log4JLogger(String name) {
107 this.name = name;
108 this.logger = getLogger();
109 }
110
111 /**
112 * For use with a log4j factory.
113 */
114 public Log4JLogger(Logger logger) {
115 if (logger == null) {
116 throw new IllegalArgumentException(
117 "Warning - null logger in constructor; possible log4j misconfiguration.");
118 }
119 this.name = logger.getName();
120 this.logger = logger;
121 }
122
123 /**
124 * Logs a message with <code>org.apache.log4j.Priority.TRACE</code>.
125 * When using a log4j version that does not support the <code>TRACE</code>
126 * level, the message will be logged at the <code>DEBUG</code> level.
127 *
128 * @param message to log
129 * @see org.apache.commons.logging.Log#trace(Object)
130 */
131 public void trace(Object message) {
132 getLogger().log(FQCN, traceLevel, message, null);
133 }
134
135 /**
136 * Logs a message with <code>org.apache.log4j.Priority.TRACE</code>.
137 * When using a log4j version that does not support the <code>TRACE</code>
138 * level, the message will be logged at the <code>DEBUG</code> level.
139 *
140 * @param message to log
141 * @param t log this cause
142 * @see org.apache.commons.logging.Log#trace(Object, Throwable)
143 */
144 public void trace(Object message, Throwable t) {
145 getLogger().log(FQCN, traceLevel, message, t);
146 }
147
148 /**
149 * Logs a message with <code>org.apache.log4j.Priority.DEBUG</code>.
150 *
151 * @param message to log
152 * @see org.apache.commons.logging.Log#debug(Object)
153 */
154 public void debug(Object message) {
155 getLogger().log(FQCN, Level.DEBUG, message, null);
156 }
157
158 /**
159 * Logs a message with <code>org.apache.log4j.Priority.DEBUG</code>.
160 *
161 * @param message to log
162 * @param t log this cause
163 * @see org.apache.commons.logging.Log#debug(Object, Throwable)
164 */
165 public void debug(Object message, Throwable t) {
166 getLogger().log(FQCN, Level.DEBUG, message, t);
167 }
168
169 /**
170 * Logs a message with <code>org.apache.log4j.Priority.INFO</code>.
171 *
172 * @param message to log
173 * @see org.apache.commons.logging.Log#info(Object)
174 */
175 public void info(Object message) {
176 getLogger().log(FQCN, Level.INFO, message, null);
177 }
178
179 /**
180 * Logs a message with <code>org.apache.log4j.Priority.INFO</code>.
181 *
182 * @param message to log
183 * @param t log this cause
184 * @see org.apache.commons.logging.Log#info(Object, Throwable)
185 */
186 public void info(Object message, Throwable t) {
187 getLogger().log(FQCN, Level.INFO, message, t);
188 }
189
190 /**
191 * Logs a message with <code>org.apache.log4j.Priority.WARN</code>.
192 *
193 * @param message to log
194 * @see org.apache.commons.logging.Log#warn(Object)
195 */
196 public void warn(Object message) {
197 getLogger().log(FQCN, Level.WARN, message, null);
198 }
199
200 /**
201 * Logs a message with <code>org.apache.log4j.Priority.WARN</code>.
202 *
203 * @param message to log
204 * @param t log this cause
205 * @see org.apache.commons.logging.Log#warn(Object, Throwable)
206 */
207 public void warn(Object message, Throwable t) {
208 getLogger().log(FQCN, Level.WARN, message, t);
209 }
210
211 /**
212 * Logs a message with <code>org.apache.log4j.Priority.ERROR</code>.
213 *
214 * @param message to log
215 * @see org.apache.commons.logging.Log#error(Object)
216 */
217 public void error(Object message) {
218 getLogger().log(FQCN, Level.ERROR, message, null);
219 }
220
221 /**
222 * Logs a message with <code>org.apache.log4j.Priority.ERROR</code>.
223 *
224 * @param message to log
225 * @param t log this cause
226 * @see org.apache.commons.logging.Log#error(Object, Throwable)
227 */
228 public void error(Object message, Throwable t) {
229 getLogger().log(FQCN, Level.ERROR, message, t);
230 }
231
232 /**
233 * Logs a message with <code>org.apache.log4j.Priority.FATAL</code>.
234 *
235 * @param message to log
236 * @see org.apache.commons.logging.Log#fatal(Object)
237 */
238 public void fatal(Object message) {
239 getLogger().log(FQCN, Level.FATAL, message, null);
240 }
241
242 /**
243 * Logs a message with <code>org.apache.log4j.Priority.FATAL</code>.
244 *
245 * @param message to log
246 * @param t log this cause
247 * @see org.apache.commons.logging.Log#fatal(Object, Throwable)
248 */
249 public void fatal(Object message, Throwable t) {
250 getLogger().log(FQCN, Level.FATAL, message, t);
251 }
252
253 /**
254 * Return the native Logger instance we are using.
255 */
256 public Logger getLogger() {
257 Logger result = logger;
258 if (result == null) {
259 synchronized(this) {
260 result = logger;
261 if (result == null) {
262 logger = result = Logger.getLogger(name);
263 }
264 }
265 }
266 return result;
267 }
268
269 /**
270 * Check whether the Log4j Logger used is enabled for <code>DEBUG</code> priority.
271 */
272 public boolean isDebugEnabled() {
273 return getLogger().isDebugEnabled();
274 }
275
276 /**
277 * Check whether the Log4j Logger used is enabled for <code>ERROR</code> priority.
278 */
279 public boolean isErrorEnabled() {
280 return getLogger().isEnabledFor(Level.ERROR);
281 }
282
283 /**
284 * Check whether the Log4j Logger used is enabled for <code>FATAL</code> priority.
285 */
286 public boolean isFatalEnabled() {
287 return getLogger().isEnabledFor(Level.FATAL);
288 }
289
290 /**
291 * Check whether the Log4j Logger used is enabled for <code>INFO</code> priority.
292 */
293 public boolean isInfoEnabled() {
294 return getLogger().isInfoEnabled();
295 }
296
297 /**
298 * Check whether the Log4j Logger used is enabled for <code>TRACE</code> priority.
299 * When using a log4j version that does not support the TRACE level, this call
300 * will report whether <code>DEBUG</code> is enabled or not.
301 */
302 public boolean isTraceEnabled() {
303 return getLogger().isEnabledFor(traceLevel);
304 }
305
306 /**
307 * Check whether the Log4j Logger used is enabled for <code>WARN</code> priority.
308 */
309 public boolean isWarnEnabled() {
310 return getLogger().isEnabledFor(Level.WARN);
311 }
312 }