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;
021
022import org.apache.commons.logging.Log;
023import org.apache.log4j.Level;
024import org.apache.log4j.Logger;
025import org.apache.log4j.Priority;
026
027/**
028 * Implementation of {@link Log} that maps directly to a
029 * <strong>Logger</strong> for log4J version 1.2.
030 * <p>
031 * Initial configuration of the corresponding Logger instances should be done
032 * in the usual manner, as outlined in the Log4J documentation.
033 * <p>
034 * The reason this logger is distinct from the 1.3.0 logger is that in version 1.2
035 * of Log4J:
036 * <ul>
037 * <li>class Logger takes Priority parameters not Level parameters.
038 * <li>class Level extends Priority
039 * </ul>
040 * Log4j 1.3 is expected to change Level so it no longer extends Priority, which is
041 * a non-binary-compatible change. The class generated by compiling this code against
042 * Log4j 1.2 will therefore not run against Log4j 1.3.
043 *
044 * @deprecated Scheduled for removal since version 1.x of Log4j has reached end-of-life.
045 */
046@Deprecated
047public class Log4JLogger implements Log, Serializable {
048
049    /** Serializable version identifier. */
050    private static final long serialVersionUID = 5160705895411730424L;
051
052    /** The fully qualified name of the Log4JLogger class. */
053    private static final String FQCN = Log4JLogger.class.getName();
054
055    private static final Priority traceLevel;
056
057    //
058    // Note that this must come after the static variable declarations
059    // otherwise initializer expressions associated with those variables
060    // will override any settings done here.
061    //
062    // Verify that Log4j is available, and that it is version 1.2.
063    // If an ExceptionInInitializerError is generated, then LogFactoryImpl
064    // will treat that as meaning that the appropriate underlying logging
065    // library is just not present - if discovery is in progress then
066    // discovery will continue.
067    static {
068        if (!Priority.class.isAssignableFrom(Level.class)) {
069            // nope, this is Log4j 1.3, so force an ExceptionInInitializerError
070            throw new InstantiationError("Log4J 1.2 not available");
071        }
072
073        // Releases of Log4j 1.2 >= 1.2.12 have Priority.TRACE available, earlier
074        // versions do not. If TRACE is not available, then we have to map
075        // calls to Log.trace(...) onto the DEBUG level.
076
077        Priority _traceLevel;
078        try {
079            _traceLevel = (Priority) Level.class.getDeclaredField("TRACE").get(null);
080        } catch (final Exception ex) {
081            // ok, trace not available
082            _traceLevel = Level.DEBUG;
083        }
084        traceLevel = _traceLevel;
085    }
086
087    /** Log to this logger */
088    private transient volatile Logger logger;
089
090    /** Logger name */
091    private final String name;
092
093    /**
094     * Constructs a new instance.
095     */
096    public Log4JLogger() {
097        name = null;
098    }
099
100    /**
101     * For use with a Log4j factory.
102     *
103     * @param logger Logger.
104     */
105    public Log4JLogger(final Logger logger) {
106        if (logger == null) {
107            throw new IllegalArgumentException(
108                "Warning - null logger in constructor; possible Log4j misconfiguration.");
109        }
110        this.name = logger.getName();
111        this.logger = logger;
112    }
113
114    /**
115     * Base constructor.
116     *
117     * @param name name.
118     */
119    public Log4JLogger(final String name) {
120        this.name = name;
121        this.logger = getLogger();
122    }
123
124    /**
125     * Logs a message with {@code org.apache.log4j.Priority.DEBUG}.
126     *
127     * @param message to log
128     * @see org.apache.commons.logging.Log#debug(Object)
129     */
130    @Override
131    public void debug(final Object message) {
132        getLogger().log(FQCN, Level.DEBUG, message, null);
133    }
134
135    /**
136     * Logs a message with {@code org.apache.log4j.Priority.DEBUG}.
137     *
138     * @param message to log
139     * @param t log this cause
140     * @see org.apache.commons.logging.Log#debug(Object, Throwable)
141     */
142    @Override
143    public void debug(final Object message, final Throwable t) {
144        getLogger().log(FQCN, Level.DEBUG, message, t);
145    }
146
147    /**
148     * Logs a message with {@code org.apache.log4j.Priority.ERROR}.
149     *
150     * @param message to log
151     * @see org.apache.commons.logging.Log#error(Object)
152     */
153    @Override
154    public void error(final Object message) {
155        getLogger().log(FQCN, Level.ERROR, message, null);
156    }
157
158    /**
159     * Logs a message with {@code org.apache.log4j.Priority.ERROR}.
160     *
161     * @param message to log
162     * @param t log this cause
163     * @see org.apache.commons.logging.Log#error(Object, Throwable)
164     */
165    @Override
166    public void error(final Object message, final Throwable t) {
167        getLogger().log(FQCN, Level.ERROR, message, t);
168    }
169
170    /**
171     * Logs a message with {@code org.apache.log4j.Priority.FATAL}.
172     *
173     * @param message to log
174     * @see org.apache.commons.logging.Log#fatal(Object)
175     */
176    @Override
177    public void fatal(final Object message) {
178        getLogger().log(FQCN, Level.FATAL, message, null);
179    }
180
181    /**
182     * Logs a message with {@code org.apache.log4j.Priority.FATAL}.
183     *
184     * @param message to log
185     * @param t log this cause
186     * @see org.apache.commons.logging.Log#fatal(Object, Throwable)
187     */
188    @Override
189    public void fatal(final Object message, final Throwable t) {
190        getLogger().log(FQCN, Level.FATAL, message, t);
191    }
192
193    /**
194     * Gets the native Logger instance we are using.
195     *
196     * @return the native Logger instance we are using.
197     */
198    public Logger getLogger() {
199        Logger result = logger;
200        if (result == null) {
201            synchronized(this) {
202                result = logger;
203                if (result == null) {
204                    logger = result = Logger.getLogger(name);
205                }
206            }
207        }
208        return result;
209    }
210
211    /**
212     * Logs a message with {@code org.apache.log4j.Priority.INFO}.
213     *
214     * @param message to log
215     * @see org.apache.commons.logging.Log#info(Object)
216     */
217    @Override
218    public void info(final Object message) {
219        getLogger().log(FQCN, Level.INFO, message, null);
220    }
221
222    /**
223     * Logs a message with {@code org.apache.log4j.Priority.INFO}.
224     *
225     * @param message to log
226     * @param t log this cause
227     * @see org.apache.commons.logging.Log#info(Object, Throwable)
228     */
229    @Override
230    public void info(final Object message, final Throwable t) {
231        getLogger().log(FQCN, Level.INFO, message, t);
232    }
233
234    /**
235     * Tests whether the Log4j Logger used is enabled for {@code DEBUG} priority.
236     */
237    @Override
238    public boolean isDebugEnabled() {
239        return getLogger().isDebugEnabled();
240    }
241
242    /**
243     * Tests whether the Log4j Logger used is enabled for {@code ERROR} priority.
244     */
245    @Override
246    public boolean isErrorEnabled() {
247        return getLogger().isEnabledFor(Level.ERROR);
248    }
249
250    /**
251     * Tests whether the Log4j Logger used is enabled for {@code FATAL} priority.
252     */
253    @Override
254    public boolean isFatalEnabled() {
255        return getLogger().isEnabledFor(Level.FATAL);
256    }
257
258    /**
259     * Tests whether the Log4j Logger used is enabled for {@code INFO} priority.
260     */
261    @Override
262    public boolean isInfoEnabled() {
263        return getLogger().isInfoEnabled();
264    }
265
266    /**
267     * Tests whether the Log4j Logger used is enabled for {@code TRACE} priority.
268     * When using a Log4j version that does not support the TRACE level, this call
269     * will report whether {@code DEBUG} is enabled or not.
270     */
271    @Override
272    public boolean isTraceEnabled() {
273        return getLogger().isEnabledFor(traceLevel);
274    }
275
276    /**
277     * Tests whether the Log4j Logger used is enabled for {@code WARN} priority.
278     */
279    @Override
280    public boolean isWarnEnabled() {
281        return getLogger().isEnabledFor(Level.WARN);
282    }
283
284    /**
285     * Logs a message with {@code org.apache.log4j.Priority.TRACE}.
286     * When using a Log4j version that does not support the {@code TRACE}
287     * level, the message will be logged at the {@code DEBUG} level.
288     *
289     * @param message to log
290     * @see org.apache.commons.logging.Log#trace(Object)
291     */
292    @Override
293    public void trace(final Object message) {
294        getLogger().log(FQCN, traceLevel, message, null);
295    }
296
297    /**
298     * Logs a message with {@code org.apache.log4j.Priority.TRACE}.
299     * When using a Log4j version that does not support the {@code TRACE}
300     * level, the message will be logged at the {@code DEBUG} level.
301     *
302     * @param message to log
303     * @param t log this cause
304     * @see org.apache.commons.logging.Log#trace(Object, Throwable)
305     */
306    @Override
307    public void trace(final Object message, final Throwable t) {
308        getLogger().log(FQCN, traceLevel, message, t);
309    }
310
311    /**
312     * Logs a message with {@code org.apache.log4j.Priority.WARN}.
313     *
314     * @param message to log
315     * @see org.apache.commons.logging.Log#warn(Object)
316     */
317    @Override
318    public void warn(final Object message) {
319        getLogger().log(FQCN, Level.WARN, message, null);
320    }
321
322    /**
323     * Logs a message with {@code org.apache.log4j.Priority.WARN}.
324     *
325     * @param message to log
326     * @param t log this cause
327     * @see org.apache.commons.logging.Log#warn(Object, Throwable)
328     */
329    @Override
330    public void warn(final Object message, final Throwable t) {
331        getLogger().log(FQCN, Level.WARN, message, t);
332    }
333
334}