Source code

001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017
018package org.apache.commons.logging.impl;
019
020import java.io.Serializable;
021import org.apache.commons.logging.Log;
022import org.apache.log4j.Logger;
023import org.apache.log4j.Priority;
024import org.apache.log4j.Level;
025
026/**
027 * Implementation of {@link Log} that maps directly to a
028 * <strong>Logger</strong> for log4J version 1.2.
029 * <p>
030 * Initial configuration of the corresponding Logger instances should be done
031 * in the usual manner, as outlined in the Log4J documentation.
032 * <p>
033 * The reason this logger is distinct from the 1.3 logger is that in version 1.2
034 * of Log4J:
035 * <ul>
036 * <li>class Logger takes Priority parameters not Level parameters.
037 * <li>class Level extends Priority
038 * </ul>
039 * Log4J1.3 is expected to change Level so it no longer extends Priority, which is
040 * a non-binary-compatible change. The class generated by compiling this code against
041 * log4j 1.2 will therefore not run against log4j 1.3.
042 *
043 * @version $Id: Log4JLogger.html 915605 2014-07-09 20:22:43Z tn $
044 */
045public class Log4JLogger implements Log, Serializable {
046
047    /** Serializable version identifier. */
048    private static final long serialVersionUID = 5160705895411730424L;
049
050    // ------------------------------------------------------------- Attributes
051
052    /** The fully qualified name of the Log4JLogger class. */
053    private static final String FQCN = Log4JLogger.class.getName();
054
055    /** Log to this logger */
056    private transient volatile Logger logger = null;
057
058    /** Logger name */
059    private final String name;
060
061    private static final Priority traceLevel;
062
063    // ------------------------------------------------------------
064    // Static Initializer.
065    //
066    // Note that this must come after the static variable declarations
067    // otherwise initialiser expressions associated with those variables
068    // will override any settings done here.
069    //
070    // Verify that log4j is available, and that it is version 1.2.
071    // If an ExceptionInInitializerError is generated, then LogFactoryImpl
072    // will treat that as meaning that the appropriate underlying logging
073    // library is just not present - if discovery is in progress then
074    // discovery will continue.
075    // ------------------------------------------------------------
076
077    static {
078        if (!Priority.class.isAssignableFrom(Level.class)) {
079            // nope, this is log4j 1.3, so force an ExceptionInInitializerError
080            throw new InstantiationError("Log4J 1.2 not available");
081        }
082
083        // Releases of log4j1.2 >= 1.2.12 have Priority.TRACE available, earlier
084        // versions do not. If TRACE is not available, then we have to map
085        // calls to Log.trace(...) onto the DEBUG level.
086
087        Priority _traceLevel;
088        try {
089            _traceLevel = (Priority) Level.class.getDeclaredField("TRACE").get(null);
090        } catch(Exception ex) {
091            // ok, trace not available
092            _traceLevel = Level.DEBUG;
093        }
094        traceLevel = _traceLevel;
095    }
096
097    // ------------------------------------------------------------ Constructor
098
099    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}