Log4JLogger xref

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    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
    19  package org.apache.commons.logging.impl;
    20
    21  import java.io.Serializable;
    22  import org.apache.commons.logging.Log;
    23  import org.apache.log4j.Logger;
    24  import org.apache.log4j.Priority;
    25  import org.apache.log4j.Level;
    26
    27  /**
    28   * Implementation of {@link Log} that maps directly to a
    29   * <strong>Logger</strong> for log4J version 1.2.
    30   * <p>
    31   * Initial configuration of the corresponding Logger instances should be done
    32   * in the usual manner, as outlined in the Log4J documentation.
    33   * <p>
    34   * The reason this logger is distinct from the 1.3 logger is that in version 1.2
    35   * of Log4J:
    36   * <ul>
    37   * <li>class Logger takes Priority parameters not Level parameters.
    38   * <li>class Level extends Priority
    39   * </ul>
    40   * Log4J1.3 is expected to change Level so it no longer extends Priority, which is
    41   * a non-binary-compatible change. The class generated by compiling this code against
    42   * log4j 1.2 will therefore not run against log4j 1.3.
    43   *
    44   * @author <a href="mailto:sanders@apache.org">Scott Sanders</a>
    45   * @author Rod Waldhoff
    46   * @author Robert Burrell Donkin
    47   * @version $Id: Log4JLogger.java 479747 2006-11-27 20:15:01Z dennisl $
    48   */
    49
    50  public class Log4JLogger implements Log, Serializable {
    51
    52      // ------------------------------------------------------------- Attributes
    53
    54      /** The fully qualified name of the Log4JLogger class. */
    55      private static final String FQCN = Log4JLogger.class.getName();
    56
    57      /** Log to this logger */
    58      private transient Logger logger = null;
    59
    60      /** Logger name */
    61      private String name = null;
    62
    63      private static Priority traceLevel;
    64
    65      // ------------------------------------------------------------
    66      // Static Initializer.
    67      //
    68      // Note that this must come after the static variable declarations
    69      // otherwise initialiser expressions associated with those variables
    70      // will override any settings done here.
    71      //
    72      // Verify that log4j is available, and that it is version 1.2.
    73      // If an ExceptionInInitializerError is generated, then LogFactoryImpl
    74      // will treat that as meaning that the appropriate underlying logging
    75      // library is just not present - if discovery is in progress then
    76      // discovery will continue.
    77      // ------------------------------------------------------------
    78
    79      static {
    80          if (!Priority.class.isAssignableFrom(Level.class)) {
    81              // nope, this is log4j 1.3, so force an ExceptionInInitializerError
    82              throw new InstantiationError("Log4J 1.2 not available");
    83          }
    84
    85          // Releases of log4j1.2 >= 1.2.12 have Priority.TRACE available, earlier
    86          // versions do not. If TRACE is not available, then we have to map
    87          // calls to Log.trace(...) onto the DEBUG level.
    88
    89          try {
    90              traceLevel = (Priority) Level.class.getDeclaredField("TRACE").get(null);
    91          } catch(Exception ex) {
    92              // ok, trace not available
    93              traceLevel = Priority.DEBUG;
    94          }
    95      }
    96
    97
    98      // ------------------------------------------------------------ Constructor
    99
    100     public Log4JLogger() {
    101     }
    102
    103
    104     /**
    105      * Base constructor.
    106      */
    107     public Log4JLogger(String name) {
    108         this.name = name;
    109         this.logger = getLogger();
    110     }
    111
    112     /**
    113      * For use with a log4j factory.
    114      */
    115     public Log4JLogger(Logger logger ) {
    116         if (logger == null) {
    117             throw new IllegalArgumentException(
    118                 "Warning - null logger in constructor; possible log4j misconfiguration.");
    119         }
    120         this.name = logger.getName();
    121         this.logger=logger;
    122     }
    123
    124
    125     // ---------------------------------------------------------
    126     // Implementation
    127     //
    128     // Note that in the methods below the Priority class is used to define
    129     // levels even though the Level class is supported in 1.2. This is done
    130     // so that at compile time the call definitely resolves to a call to
    131     // a method that takes a Priority rather than one that takes a Level.
    132     //
    133     // The Category class (and hence its subclass Logger) in version 1.2 only
    134     // has methods that take Priority objects. The Category class (and hence
    135     // Logger class) in version 1.3 has methods that take both Priority and
    136     // Level objects. This means that if we use Level here, and compile
    137     // against log4j 1.3 then calls would be bound to the versions of
    138     // methods taking Level objects and then would fail to run against
    139     // version 1.2 of log4j.
    140     // ---------------------------------------------------------
    141
    142
    143     /**
    144      * Logs a message with <code>org.apache.log4j.Priority.TRACE</code>.
    145      * When using a log4j version that does not support the <code>TRACE</code>
    146      * level, the message will be logged at the <code>DEBUG</code> level.
    147      *
    148      * @param message to log
    149      * @see org.apache.commons.logging.Log#trace(Object)
    150      */
    151     public void trace(Object message) {
    152         getLogger().log(FQCN, traceLevel, message, null );
    153     }
    154
    155
    156     /**
    157      * Logs a message with <code>org.apache.log4j.Priority.TRACE</code>.
    158      * When using a log4j version that does not support the <code>TRACE</code>
    159      * level, the message will be logged at the <code>DEBUG</code> level.
    160      *
    161      * @param message to log
    162      * @param t log this cause
    163      * @see org.apache.commons.logging.Log#trace(Object, Throwable)
    164      */
    165     public void trace(Object message, Throwable t) {
    166         getLogger().log(FQCN, traceLevel, message, t );
    167     }
    168
    169
    170     /**
    171      * Logs a message with <code>org.apache.log4j.Priority.DEBUG</code>.
    172      *
    173      * @param message to log
    174      * @see org.apache.commons.logging.Log#debug(Object)
    175      */
    176     public void debug(Object message) {
    177         getLogger().log(FQCN, Priority.DEBUG, message, null );
    178     }
    179
    180     /**
    181      * Logs a message with <code>org.apache.log4j.Priority.DEBUG</code>.
    182      *
    183      * @param message to log
    184      * @param t log this cause
    185      * @see org.apache.commons.logging.Log#debug(Object, Throwable)
    186      */
    187     public void debug(Object message, Throwable t) {
    188         getLogger().log(FQCN, Priority.DEBUG, message, t );
    189     }
    190
    191
    192     /**
    193      * Logs a message with <code>org.apache.log4j.Priority.INFO</code>.
    194      *
    195      * @param message to log
    196      * @see org.apache.commons.logging.Log#info(Object)
    197      */
    198     public void info(Object message) {
    199         getLogger().log(FQCN, Priority.INFO, message, null );
    200     }
    201
    202
    203     /**
    204      * Logs a message with <code>org.apache.log4j.Priority.INFO</code>.
    205      *
    206      * @param message to log
    207      * @param t log this cause
    208      * @see org.apache.commons.logging.Log#info(Object, Throwable)
    209      */
    210     public void info(Object message, Throwable t) {
    211         getLogger().log(FQCN, Priority.INFO, message, t );
    212     }
    213
    214
    215     /**
    216      * Logs a message with <code>org.apache.log4j.Priority.WARN</code>.
    217      *
    218      * @param message to log
    219      * @see org.apache.commons.logging.Log#warn(Object)
    220      */
    221     public void warn(Object message) {
    222         getLogger().log(FQCN, Priority.WARN, message, null );
    223     }
    224
    225
    226     /**
    227      * Logs a message with <code>org.apache.log4j.Priority.WARN</code>.
    228      *
    229      * @param message to log
    230      * @param t log this cause
    231      * @see org.apache.commons.logging.Log#warn(Object, Throwable)
    232      */
    233     public void warn(Object message, Throwable t) {
    234         getLogger().log(FQCN, Priority.WARN, message, t );
    235     }
    236
    237
    238     /**
    239      * Logs a message with <code>org.apache.log4j.Priority.ERROR</code>.
    240      *
    241      * @param message to log
    242      * @see org.apache.commons.logging.Log#error(Object)
    243      */
    244     public void error(Object message) {
    245         getLogger().log(FQCN, Priority.ERROR, message, null );
    246     }
    247
    248
    249     /**
    250      * Logs a message with <code>org.apache.log4j.Priority.ERROR</code>.
    251      *
    252      * @param message to log
    253      * @param t log this cause
    254      * @see org.apache.commons.logging.Log#error(Object, Throwable)
    255      */
    256     public void error(Object message, Throwable t) {
    257         getLogger().log(FQCN, Priority.ERROR, message, t );
    258     }
    259
    260
    261     /**
    262      * Logs a message with <code>org.apache.log4j.Priority.FATAL</code>.
    263      *
    264      * @param message to log
    265      * @see org.apache.commons.logging.Log#fatal(Object)
    266      */
    267     public void fatal(Object message) {
    268         getLogger().log(FQCN, Priority.FATAL, message, null );
    269     }
    270
    271
    272     /**
    273      * Logs a message with <code>org.apache.log4j.Priority.FATAL</code>.
    274      *
    275      * @param message to log
    276      * @param t log this cause
    277      * @see org.apache.commons.logging.Log#fatal(Object, Throwable)
    278      */
    279     public void fatal(Object message, Throwable t) {
    280         getLogger().log(FQCN, Priority.FATAL, message, t );
    281     }
    282
    283
    284     /**
    285      * Return the native Logger instance we are using.
    286      */
    287     public Logger getLogger() {
    288         if (logger == null) {
    289             logger = Logger.getLogger(name);
    290         }
    291         return (this.logger);
    292     }
    293
    294
    295     /**
    296      * Check whether the Log4j Logger used is enabled for <code>DEBUG</code> priority.
    297      */
    298     public boolean isDebugEnabled() {
    299         return getLogger().isDebugEnabled();
    300     }
    301
    302
    303      /**
    304      * Check whether the Log4j Logger used is enabled for <code>ERROR</code> priority.
    305      */
    306     public boolean isErrorEnabled() {
    307         return getLogger().isEnabledFor(Priority.ERROR);
    308     }
    309
    310
    311     /**
    312      * Check whether the Log4j Logger used is enabled for <code>FATAL</code> priority.
    313      */
    314     public boolean isFatalEnabled() {
    315         return getLogger().isEnabledFor(Priority.FATAL);
    316     }
    317
    318
    319     /**
    320      * Check whether the Log4j Logger used is enabled for <code>INFO</code> priority.
    321      */
    322     public boolean isInfoEnabled() {
    323         return getLogger().isInfoEnabled();
    324     }
    325
    326
    327     /**
    328      * Check whether the Log4j Logger used is enabled for <code>TRACE</code> priority.
    329      * When using a log4j version that does not support the TRACE level, this call
    330      * will report whether <code>DEBUG</code> is enabled or not.
    331      */
    332     public boolean isTraceEnabled() {
    333         return getLogger().isEnabledFor(traceLevel);
    334     }
    335
    336     /**
    337      * Check whether the Log4j Logger used is enabled for <code>WARN</code> priority.
    338      */
    339     public boolean isWarnEnabled() {
    340         return getLogger().isEnabledFor(Priority.WARN);
    341     }
    342 }