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.logging.log4j.core; 18 19 import java.io.Serializable; 20 21 /** 22 * Appends {@link LogEvent}s. An Appender can contain a {@link Layout} if applicable as well 23 * as an {@link ErrorHandler}. Typical Appender implementations coordinate with an 24 * implementation of {@link org.apache.logging.log4j.core.appender.AbstractManager} to handle external resources 25 * such as streams, connections, and other shared state. As Appenders are plugins, concrete implementations need to 26 * be annotated with {@link org.apache.logging.log4j.core.config.plugins.Plugin} and need to provide a static 27 * factory method annotated with {@link org.apache.logging.log4j.core.config.plugins.PluginFactory}. 28 * 29 * <p>Most core plugins are written using a related Manager class that handle the actual task of serializing a 30 * {@link LogEvent} to some output location. For instance, many Appenders can take 31 * advantage of the {@link org.apache.logging.log4j.core.appender.OutputStreamManager} class.</p> 32 * 33 * <p>It is recommended that Appenders don't do any heavy lifting since there can be many instances of the class 34 * being used at any given time. When resources require locking (e.g., through {@link java.nio.channels.FileLock}), 35 * it is important to isolate synchronized code to prevent concurrency issues.</p> 36 */ 37 public interface Appender extends LifeCycle { 38 39 /** 40 * Logs a LogEvent using whatever logic this Appender wishes to use. It is typically recommended to use a 41 * bridge pattern not only for the benefits from decoupling an Appender from its implementation, but it is also 42 * handy for sharing resources which may require some form of locking. 43 * 44 * @param event The LogEvent. 45 */ 46 void append(LogEvent event); 47 48 49 /** 50 * Get the name of this Appender. 51 * 52 * @return name, may be null. 53 */ 54 String getName(); 55 56 /** 57 * Returns the Layout used by this Appender if applicable. 58 * 59 * @return the Layout for this Appender or {@code null} if none is configured. 60 */ 61 Layout<? extends Serializable> getLayout(); 62 63 /** 64 * Some Appenders need to propagate exceptions back to the application. When {@code ignoreExceptions} is 65 * {@code false} the AppenderControl will allow the exception to percolate. 66 * 67 * @return {@code true} if exceptions will be logged but not thrown, {@code false} otherwise. 68 */ 69 boolean ignoreExceptions(); 70 71 /** 72 * Gets the {@link ErrorHandler} used for handling exceptions. 73 * 74 * @return the ErrorHandler for handling exceptions. 75 */ 76 ErrorHandler getHandler(); 77 78 /** 79 * Sets the {@link ErrorHandler} used for handling exceptions. 80 * 81 * @param handler the ErrorHandler to use for handling exceptions. 82 */ 83 void setHandler(ErrorHandler handler); 84 }