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 package org.apache.log4j; 18 19 import org.apache.log4j.spi.Filter; 20 import org.apache.log4j.spi.ErrorHandler; 21 import org.apache.log4j.spi.LoggingEvent; 22 23 /** 24 * Implement this interface for your own strategies for outputting log 25 * statements. 26 * 27 * @author Ceki Gülcü 28 */ 29 public interface Appender { 30 31 /** 32 * Add a filter to the end of the filter list. 33 * @param newFilter The filter to add. 34 * 35 * @since 0.9.0 36 */ 37 void addFilter(Filter newFilter); 38 39 /** 40 * Returns the head Filter. The Filters are organized in a linked list 41 * and so all Filters on this Appender are available through the result. 42 * 43 * @return the head Filter or null, if no Filters are present 44 * @since 1.1 45 */ 46 Filter getFilter(); 47 48 /** 49 * Clear the list of filters by removing all the filters in it. 50 * 51 * @since 0.9.0 52 */ 53 void clearFilters(); 54 55 /** 56 * Release any resources allocated within the appender such as file 57 * handles, network connections, etc. 58 * <p/> 59 * <p>It is a programming error to append to a closed appender. 60 * 61 * @since 0.8.4 62 */ 63 void close(); 64 65 /** 66 * Log in <code>Appender</code> specific way. When appropriate, 67 * Loggers will call the <code>doAppend</code> method of appender 68 * implementations in order to log. 69 * @param event The LoggingEvent. 70 */ 71 void doAppend(LoggingEvent event); 72 73 74 /** 75 * Get the name of this appender. 76 * 77 * @return name, may be null. 78 */ 79 String getName(); 80 81 82 /** 83 * Set the {@link ErrorHandler} for this appender. 84 * @param errorHandler The error handler. 85 * 86 * @since 0.9.0 87 */ 88 void setErrorHandler(ErrorHandler errorHandler); 89 90 /** 91 * Returns the {@link ErrorHandler} for this appender. 92 * @return The error handler. 93 * 94 * @since 1.1 95 */ 96 ErrorHandler getErrorHandler(); 97 98 /** 99 * 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