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 * 34 * @since 0.9.0 35 */ 36 void addFilter(Filter newFilter); 37 38 /** 39 * Returns the head Filter. The Filters are organized in a linked list 40 * and so all Filters on this Appender are available through the result. 41 * 42 * @return the head Filter or null, if no Filters are present 43 * @since 1.1 44 */ 45 public Filter getFilter(); 46 47 /** 48 * Clear the list of filters by removing all the filters in it. 49 * 50 * @since 0.9.0 51 */ 52 public void clearFilters(); 53 54 /** 55 * Release any resources allocated within the appender such as file 56 * handles, network connections, etc. 57 * <p/> 58 * <p>It is a programming error to append to a closed appender. 59 * 60 * @since 0.8.4 61 */ 62 public void close(); 63 64 /** 65 * Log in <code>Appender</code> specific way. When appropriate, 66 * Loggers will call the <code>doAppend</code> method of appender 67 * implementations in order to log. 68 */ 69 public void doAppend(LoggingEvent event); 70 71 72 /** 73 * Get the name of this appender. 74 * 75 * @return name, may be null. 76 */ 77 public String getName(); 78 79 80 /** 81 * Set the {@link ErrorHandler} for this appender. 82 * 83 * @since 0.9.0 84 */ 85 public void setErrorHandler(ErrorHandler errorHandler); 86 87 /** 88 * Returns the {@link ErrorHandler} for this appender. 89 * 90 * @since 1.1 91 */ 92 public ErrorHandler getErrorHandler(); 93 94 /** 95 * Set the {@link Layout} for this appender. 96 * 97 * @since 0.8.1 98 */ 99 public void setLayout(Layout layout); 100 101 /** 102 * Returns this appenders layout. 103 * 104 * @since 1.1 105 */ 106 public Layout getLayout(); 107 108 109 /** 110 * Set the name of this appender. The name is used by other 111 * components to identify this appender. 112 * 113 * @since 0.8.1 114 */ 115 public void setName(String name); 116 117 /** 118 * Configurators call this method to determine if the appender 119 * requires a layout. If this method returns {@code true}, 120 * meaning that layout is required, then the configurator will 121 * configure an layout using the configuration information at its 122 * disposal. If this method returns {@code false}, meaning that 123 * a layout is not required, then layout configuration will be 124 * skipped even if there is available layout configuration 125 * information at the disposal of the configurator.. 126 * <p/> 127 * <p>In the rather exceptional case, where the appender 128 * implementation admits a layout but can also work without it, then 129 * the appender should return {@code true}. 130 * 131 * @since 0.8.4 132 */ 133 public boolean requiresLayout(); 134 } 135