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 *      https://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 * Implements {@link Log} to map directly to a
029 * <strong>Logger</strong> for Apache 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.</li>
038 * <li>class Level extends Priority</li>
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 TRACE_LEVEL;
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        // Releases of Log4j 1.2 >= 1.2.12 have Priority.TRACE available, earlier
073        // versions do not. If TRACE is not available, then we have to map
074        // calls to Log.trace(...) onto the DEBUG level.
075        Priority traceLevel;
076        try {
077            traceLevel = (Priority) Level.class.getDeclaredField("TRACE").get(null);
078        } catch (final Exception ex) {
079            // ok, trace not available
080            traceLevel = Level.DEBUG;
081        }
082        TRACE_LEVEL = traceLevel;
083    }
084
085    /** Log to this logger */
086    private transient volatile Logger logger;
087
088    /** Logger name */
089    private final String name;
090
091    /**
092     * Constructs a new instance.
093     */
094    public Log4JLogger() {
095        name = null;
096    }
097
098    /**
099     * For use with a Log4j factory.
100     *
101     * @param logger Logger.
102     */
103    public Log4JLogger(final Logger logger) {
104        if (logger == null) {
105            throw new IllegalArgumentException("Warning - null logger in constructor; possible Log4j misconfiguration.");
106        }
107        this.name = logger.getName();
108        this.logger = logger;
109    }
110
111    /**
112     * Base constructor.
113     *
114     * @param name name.
115     */
116    public Log4JLogger(final String name) {
117        this.name = name;
118        this.logger = getLogger();
119    }
120
121    /**
122     * Logs a message with {@code org.apache.log4j.Priority.DEBUG}.
123     *
124     * @param message to log
125     * @see org.apache.commons.logging.Log#debug(Object)
126     */
127    @Override
128    public void debug(final Object message) {
129        getLogger().log(FQCN, Level.DEBUG, message, null);
130    }
131
132    /**
133     * Logs a message with {@code org.apache.log4j.Priority.DEBUG}.
134     *
135     * @param message to log
136     * @param t log this cause
137     * @see org.apache.commons.logging.Log#debug(Object, Throwable)
138     */
139    @Override
140    public void debug(final Object message, final Throwable t) {
141        getLogger().log(FQCN, Level.DEBUG, message, t);
142    }
143
144    /**
145     * Logs a message with {@code org.apache.log4j.Priority.ERROR}.
146     *
147     * @param message to log
148     * @see org.apache.commons.logging.Log#error(Object)
149     */
150    @Override
151    public void error(final Object message) {
152        getLogger().log(FQCN, Level.ERROR, message, null);
153    }
154
155    /**
156     * Logs a message with {@code org.apache.log4j.Priority.ERROR}.
157     *
158     * @param message to log
159     * @param t log this cause
160     * @see org.apache.commons.logging.Log#error(Object, Throwable)
161     */
162    @Override
163    public void error(final Object message, final Throwable t) {
164        getLogger().log(FQCN, Level.ERROR, message, t);
165    }
166
167    /**
168     * Logs a message with {@code org.apache.log4j.Priority.FATAL}.
169     *
170     * @param message to log
171     * @see org.apache.commons.logging.Log#fatal(Object)
172     */
173    @Override
174    public void fatal(final Object message) {
175        getLogger().log(FQCN, Level.FATAL, message, null);
176    }
177
178    /**
179     * Logs a message with {@code org.apache.log4j.Priority.FATAL}.
180     *
181     * @param message to log
182     * @param t log this cause
183     * @see org.apache.commons.logging.Log#fatal(Object, Throwable)
184     */
185    @Override
186    public void fatal(final Object message, final Throwable t) {
187        getLogger().log(FQCN, Level.FATAL, message, t);
188    }
189
190    /**
191     * Gets the native Logger instance we are using.
192     *
193     * @return the native Logger instance we are using.
194     */
195    public Logger getLogger() {
196        Logger result = logger;
197        if (result == null) {
198            synchronized(this) {
199                result = logger;
200                if (result == null) {
201                    logger = result = Logger.getLogger(name);
202                }
203            }
204        }
205        return result;
206    }
207
208    /**
209     * Logs a message with {@code org.apache.log4j.Priority.INFO}.
210     *
211     * @param message to log
212     * @see org.apache.commons.logging.Log#info(Object)
213     */
214    @Override
215    public void info(final Object message) {
216        getLogger().log(FQCN, Level.INFO, message, null);
217    }
218
219    /**
220     * Logs a message with {@code org.apache.log4j.Priority.INFO}.
221     *
222     * @param message to log
223     * @param t log this cause
224     * @see org.apache.commons.logging.Log#info(Object, Throwable)
225     */
226    @Override
227    public void info(final Object message, final Throwable t) {
228        getLogger().log(FQCN, Level.INFO, message, t);
229    }
230
231    /**
232     * Tests whether the Log4j Logger used is enabled for {@code DEBUG} priority.
233     */
234    @Override
235    public boolean isDebugEnabled() {
236        return getLogger().isDebugEnabled();
237    }
238
239    /**
240     * Tests whether the Log4j Logger used is enabled for {@code ERROR} priority.
241     */
242    @Override
243    public boolean isErrorEnabled() {
244        return getLogger().isEnabledFor(Level.ERROR);
245    }
246
247    /**
248     * Tests whether the Log4j Logger used is enabled for {@code FATAL} priority.
249     */
250    @Override
251    public boolean isFatalEnabled() {
252        return getLogger().isEnabledFor(Level.FATAL);
253    }
254
255    /**
256     * Tests whether the Log4j Logger used is enabled for {@code INFO} priority.
257     */
258    @Override
259    public boolean isInfoEnabled() {
260        return getLogger().isInfoEnabled();
261    }
262
263    /**
264     * Tests whether the Log4j Logger used is enabled for {@code TRACE} priority.
265     * When using a Log4j version that does not support the TRACE level, this call
266     * will report whether {@code DEBUG} is enabled or not.
267     */
268    @Override
269    public boolean isTraceEnabled() {
270        return getLogger().isEnabledFor(TRACE_LEVEL);
271    }
272
273    /**
274     * Tests whether the Log4j Logger used is enabled for {@code WARN} priority.
275     */
276    @Override
277    public boolean isWarnEnabled() {
278        return getLogger().isEnabledFor(Level.WARN);
279    }
280
281    /**
282     * Logs a message with {@code org.apache.log4j.Priority.TRACE}.
283     * When using a Log4j version that does not support the {@code TRACE}
284     * level, the message will be logged at the {@code DEBUG} level.
285     *
286     * @param message to log
287     * @see org.apache.commons.logging.Log#trace(Object)
288     */
289    @Override
290    public void trace(final Object message) {
291        getLogger().log(FQCN, TRACE_LEVEL, message, null);
292    }
293
294    /**
295     * Logs a message with {@code org.apache.log4j.Priority.TRACE}.
296     * When using a Log4j version that does not support the {@code TRACE}
297     * level, the message will be logged at the {@code DEBUG} level.
298     *
299     * @param message to log
300     * @param t log this cause
301     * @see org.apache.commons.logging.Log#trace(Object, Throwable)
302     */
303    @Override
304    public void trace(final Object message, final Throwable t) {
305        getLogger().log(FQCN, TRACE_LEVEL, message, t);
306    }
307
308    /**
309     * Logs a message with {@code org.apache.log4j.Priority.WARN}.
310     *
311     * @param message to log
312     * @see org.apache.commons.logging.Log#warn(Object)
313     */
314    @Override
315    public void warn(final Object message) {
316        getLogger().log(FQCN, Level.WARN, message, null);
317    }
318
319    /**
320     * Logs a message with {@code org.apache.log4j.Priority.WARN}.
321     *
322     * @param message to log
323     * @param t log this cause
324     * @see org.apache.commons.logging.Log#warn(Object, Throwable)
325     */
326    @Override
327    public void warn(final Object message, final Throwable t) {
328        getLogger().log(FQCN, Level.WARN, message, t);
329    }
330
331}