/* * Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements.  See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You under the Apache License, Version 2.0 * (the "License"); you may not use this file except in compliance with * the License.  You may obtain a copy of the License at *  *      http://www.apache.org/licenses/LICENSE-2.0 *  * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */package org.apache.log4j;import org.apache.log4j.spi.Filter;import org.apache.log4j.spi.ErrorHandler;import org.apache.log4j.spi.LoggingEvent;/**   Implement this interface for your own strategies for outputting log   statements.   @author Ceki G&uuml;lc&uuml; */public interface Appender {  /**     Add a filter to the end of the filter list.     @since 0.9.0   */  void addFilter(Filter newFilter);  /**     Returns the head Filter. The Filters are organized in a linked list     and so all Filters on this Appender are available through the result.          @return the head Filter or null, if no Filters are present     @since 1.1  */  public  Filter getFilter();  /**     Clear the list of filters by removing all the filters in it.          @since 0.9.0   */  public  void clearFilters();  /**     Release any resources allocated within the appender such as file     handles, network connections, etc.     <p>It is a programming error to append to a closed appender.     @since 0.8.4  */  public  void close();    /**     Log in <code>Appender</code> specific way. When appropriate,     Loggers will call the <code>doAppend</code> method of appender     implementations in order to log. */  public  void doAppend(LoggingEvent event);  /**     Get the name of this appender. The name uniquely identifies the     appender.  */  public  String getName();  /**     Set the {@link ErrorHandler} for this appender.     @since 0.9.0   */  public  void setErrorHandler(ErrorHandler errorHandler);  /**     Returns the {@link ErrorHandler} for this appender.     @since 1.1   */  public  ErrorHandler getErrorHandler();  /**     Set the {@link Layout} for this appender.     @since 0.8.1  */  public  void setLayout(Layout layout);  /**     Returns this appenders layout.          @since 1.1  */  public  Layout getLayout();    /**     Set the name of this appender. The name is used by other     components to identify this appender.     @since 0.8.1  */  public  void setName(String name);  /**     Configurators call this method to determine if the appender    requires a layout. If this method returns <code>true</code>,    meaning that layout is required, then the configurator will    configure an layout using the configuration information at its    disposal.  If this method returns <code>false</code>, meaning that    a layout is not required, then layout configuration will be    skipped even if there is available layout configuration    information at the disposal of the configurator..     <p>In the rather exceptional case, where the appender     implementation admits a layout but can also work without it, then     the appender should return <code>true</code>.          @since 0.8.4 */  public  boolean requiresLayout();}