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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  package org.apache.log4j.spi;
    19
    20  import org.apache.log4j.Appender;
    21  import org.apache.log4j.Logger;
    22
    23
    24  /**
    25   * Interface used to listen for Logger related events such as
    26   * add/remove appender or changing levels.  Clients register an instance of
    27   * the interface and the instance is called back when the various events occur.
    28   * <p>
    29   * LoggerRepository provides methods for adding and removing
    30   * LoggerEventListener instances.
    31   * <p>
    32   * When implementing the methods of this interface, it is useful to remember
    33   * that the Logger can access the repository using its getRepository()
    34   * method.
    35   *
    36   * @author Ceki G&uuml;lc&uuml;
    37   * @author Mark Womack
    38   */
    39  public interface LoggerEventListener {
    40      /**
    41       * Called when an appender is added to the logger.
    42       *
    43       * @param logger   The logger to which the appender was added.
    44       * @param appender The appender added to the logger.
    45       */
    46      void appenderAddedEvent(Logger logger, Appender appender);
    47
    48      /**
    49       * Called when an appender is removed from the logger.
    50       *
    51       * @param logger   The logger from which the appender was removed.
    52       * @param appender The appender removed from the logger.
    53       */
    54      void appenderRemovedEvent(Logger logger, Appender appender);
    55
    56      /**
    57       * Called when level changed on the logger.
    58       *
    59       * @param logger The logger that changed levels.
    60       */
    61      void levelChangedEvent(Logger logger);
    62  }