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    1   /**
    2    * Copyright (c) 2004-2011 QOS.ch
    3    * All rights reserved.
    4    *
    5    * Permission is hereby granted, free  of charge, to any person obtaining
    6    * a  copy  of this  software  and  associated  documentation files  (the
    7    * "Software"), to  deal in  the Software without  restriction, including
    8    * without limitation  the rights to  use, copy, modify,  merge, publish,
    9    * distribute,  sublicense, and/or sell  copies of  the Software,  and to
    10   * permit persons to whom the Software  is furnished to do so, subject to
    11   * the following conditions:
    12   *
    13   * The  above  copyright  notice  and  this permission  notice  shall  be
    14   * included in all copies or substantial portions of the Software.
    15   *
    16   * THE  SOFTWARE IS  PROVIDED  "AS  IS", WITHOUT  WARRANTY  OF ANY  KIND,
    17   * EXPRESS OR  IMPLIED, INCLUDING  BUT NOT LIMITED  TO THE  WARRANTIES OF
    18   * MERCHANTABILITY,    FITNESS    FOR    A   PARTICULAR    PURPOSE    AND
    19   * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
    20   * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    21   * OF CONTRACT, TORT OR OTHERWISE,  ARISING FROM, OUT OF OR IN CONNECTION
    22   * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    23   *
    24   */
    25  package org.slf4j.impl;
    26
    27  import java.util.concurrent.ConcurrentHashMap;
    28  import java.util.concurrent.ConcurrentMap;
    29
    30  import org.apache.log4j.LogManager;
    31  import org.slf4j.ILoggerFactory;
    32  import org.slf4j.Logger;
    33  import org.slf4j.helpers.Util;
    34
    35  /**
    36   * Log4jLoggerFactory is an implementation of {@link ILoggerFactory} returning
    37   * the appropriate named {@link Log4jLoggerAdapter} instance.
    38   *
    39   * @author Ceki G&uuml;lc&uuml;
    40   */
    41  public class Log4jLoggerFactory implements ILoggerFactory {
    42
    43      private static final String LOG4J_DELEGATION_LOOP_URL = "http://www.slf4j.org/codes.html#log4jDelegationLoop";
    44
    45      // check for delegation loops
    46      static {
    47          try {
    48              Class.forName("org.apache.log4j.Log4jLoggerFactory");
    49              String part1 = "Detected both log4j-over-slf4j.jar AND bound slf4j-log4j12.jar on the class path, preempting StackOverflowError. ";
    50              String part2 = "See also " + LOG4J_DELEGATION_LOOP_URL + " for more details.";
    51
    52              Util.report(part1);
    53              Util.report(part2);
    54              throw new IllegalStateException(part1 + part2);
    55          } catch (ClassNotFoundException e) {
    56              // this is the good case
    57          }
    58      }
    59
    60      // key: name (String), value: a Log4jLoggerAdapter;
    61      ConcurrentMap<String, Logger> loggerMap;
    62
    63      public Log4jLoggerFactory() {
    64          loggerMap = new ConcurrentHashMap<String, Logger>();
    65          // force log4j to initialize
    66          org.apache.log4j.LogManager.getRootLogger();
    67      }
    68
    69      /*
    70       * (non-Javadoc)
    71       *
    72       * @see org.slf4j.ILoggerFactory#getLogger(java.lang.String)
    73       */
    74      public Logger getLogger(String name) {
    75          Logger slf4jLogger = loggerMap.get(name);
    76          if (slf4jLogger != null) {
    77              return slf4jLogger;
    78          } else {
    79              org.apache.log4j.Logger log4jLogger;
    80              if (name.equalsIgnoreCase(Logger.ROOT_LOGGER_NAME))
    81                  log4jLogger = LogManager.getRootLogger();
    82              else
    83                  log4jLogger = LogManager.getLogger(name);
    84
    85              Logger newInstance = new Log4jLoggerAdapter(log4jLogger);
    86              Logger oldInstance = loggerMap.putIfAbsent(name, newInstance);
    87              return oldInstance == null ? newInstance : oldInstance;
    88          }
    89      }
    90  }