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 * http://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 package org.apache.log4j; 018 019 import org.apache.log4j.spi.Filter; 020 import org.apache.log4j.spi.ErrorHandler; 021 import org.apache.log4j.spi.LoggingEvent; 022 023 /** 024 * Implement this interface for your own strategies for outputting log 025 * statements. 026 * 027 * @author Ceki Gülcü 028 */ 029 public interface Appender { 030 031 /** 032 * Add a filter to the end of the filter list. 033 * @param newFilter The filter to add. 034 * 035 * @since 0.9.0 036 */ 037 void addFilter(Filter newFilter); 038 039 /** 040 * Returns the head Filter. The Filters are organized in a linked list 041 * and so all Filters on this Appender are available through the result. 042 * 043 * @return the head Filter or null, if no Filters are present 044 * @since 1.1 045 */ 046 Filter getFilter(); 047 048 /** 049 * Clear the list of filters by removing all the filters in it. 050 * 051 * @since 0.9.0 052 */ 053 void clearFilters(); 054 055 /** 056 * Release any resources allocated within the appender such as file 057 * handles, network connections, etc. 058 * <p/> 059 * <p>It is a programming error to append to a closed appender. 060 * 061 * @since 0.8.4 062 */ 063 void close(); 064 065 /** 066 * Log in <code>Appender</code> specific way. When appropriate, 067 * Loggers will call the <code>doAppend</code> method of appender 068 * implementations in order to log. 069 * @param event The LoggingEvent. 070 */ 071 void doAppend(LoggingEvent event); 072 073 074 /** 075 * Get the name of this appender. 076 * 077 * @return name, may be null. 078 */ 079 String getName(); 080 081 082 /** 083 * Set the {@link ErrorHandler} for this appender. 084 * @param errorHandler The error handler. 085 * 086 * @since 0.9.0 087 */ 088 void setErrorHandler(ErrorHandler errorHandler); 089 090 /** 091 * Returns the {@link ErrorHandler} for this appender. 092 * @return The error handler. 093 * 094 * @since 1.1 095 */ 096 ErrorHandler getErrorHandler(); 097 098 /** 099 * Set the {@link Layout} for this appender. 100 * @param layout The Layout. 101 * 102 * @since 0.8.1 103 */ 104 void setLayout(Layout layout); 105 106 /** 107 * Returns this appenders layout. 108 * @return the Layout. 109 * 110 * @since 1.1 111 */ 112 Layout getLayout(); 113 114 115 /** 116 * Set the name of this appender. The name is used by other 117 * components to identify this appender. 118 * @param name The appender name. 119 * 120 * @since 0.8.1 121 */ 122 void setName(String name); 123 124 /** 125 * Configurators call this method to determine if the appender 126 * requires a layout. If this method returns {@code true}, 127 * meaning that layout is required, then the configurator will 128 * configure an layout using the configuration information at its 129 * disposal. If this method returns {@code false}, meaning that 130 * a layout is not required, then layout configuration will be 131 * skipped even if there is available layout configuration 132 * information at the disposal of the configurator.. 133 * <p/> 134 * <p>In the rather exceptional case, where the appender 135 * implementation admits a layout but can also work without it, then 136 * the appender should return {@code true}. 137 * @return true if a Layout is required. 138 * 139 * @since 0.8.4 140 */ 141 boolean requiresLayout(); 142 } 143