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 */ 017package org.apache.logging.log4j.core.appender.rewrite; 018 019import java.util.concurrent.ConcurrentHashMap; 020import java.util.concurrent.ConcurrentMap; 021 022import org.apache.logging.log4j.core.Appender; 023import org.apache.logging.log4j.core.Core; 024import org.apache.logging.log4j.core.Filter; 025import org.apache.logging.log4j.core.LogEvent; 026import org.apache.logging.log4j.core.appender.AbstractAppender; 027import org.apache.logging.log4j.core.config.AppenderControl; 028import org.apache.logging.log4j.core.config.AppenderRef; 029import org.apache.logging.log4j.core.config.Configuration; 030import org.apache.logging.log4j.core.config.plugins.Plugin; 031import org.apache.logging.log4j.core.config.plugins.PluginAttribute; 032import org.apache.logging.log4j.core.config.plugins.PluginConfiguration; 033import org.apache.logging.log4j.core.config.plugins.PluginElement; 034import org.apache.logging.log4j.core.config.plugins.PluginFactory; 035import org.apache.logging.log4j.core.util.Booleans; 036 037/** 038 * This Appender allows the logging event to be manipulated before it is processed by other Appenders. 039 */ 040@Plugin(name = "Rewrite", category = Core.CATEGORY_NAME, elementType = Appender.ELEMENT_TYPE, printObject = true) 041public final class RewriteAppender extends AbstractAppender { 042 043 private final Configuration config; 044 private final ConcurrentMap<String, AppenderControl> appenders = new ConcurrentHashMap<>(); 045 private final RewritePolicy rewritePolicy; 046 private final AppenderRef[] appenderRefs; 047 048 private RewriteAppender(final String name, final Filter filter, final boolean ignoreExceptions, 049 final AppenderRef[] appenderRefs, final RewritePolicy rewritePolicy, 050 final Configuration config) { 051 super(name, filter, null, ignoreExceptions); 052 this.config = config; 053 this.rewritePolicy = rewritePolicy; 054 this.appenderRefs = appenderRefs; 055 } 056 057 @Override 058 public void start() { 059 for (final AppenderRef ref : appenderRefs) { 060 final String name = ref.getRef(); 061 final Appender appender = config.getAppender(name); 062 if (appender != null) { 063 final Filter filter = appender instanceof AbstractAppender ? 064 ((AbstractAppender) appender).getFilter() : null; 065 appenders.put(name, new AppenderControl(appender, ref.getLevel(), filter)); 066 } else { 067 LOGGER.error("Appender " + ref + " cannot be located. Reference ignored"); 068 } 069 } 070 super.start(); 071 } 072 073 /** 074 * Modifies the event and pass to the subordinate Appenders. 075 * @param event The LogEvent. 076 */ 077 @Override 078 public void append(LogEvent event) { 079 if (rewritePolicy != null) { 080 event = rewritePolicy.rewrite(event); 081 } 082 for (final AppenderControl control : appenders.values()) { 083 control.callAppender(event); 084 } 085 } 086 087 /** 088 * Creates a RewriteAppender. 089 * @param name The name of the Appender. 090 * @param ignore If {@code "true"} (default) exceptions encountered when appending events are logged; otherwise 091 * they are propagated to the caller. 092 * @param appenderRefs An array of Appender names to call. 093 * @param config The Configuration. 094 * @param rewritePolicy The policy to use to modify the event. 095 * @param filter A Filter to filter events. 096 * @return The created RewriteAppender. 097 */ 098 @PluginFactory 099 public static RewriteAppender createAppender( 100 @PluginAttribute("name") final String name, 101 @PluginAttribute("ignoreExceptions") final String ignore, 102 @PluginElement("AppenderRef") final AppenderRef[] appenderRefs, 103 @PluginConfiguration final Configuration config, 104 @PluginElement("RewritePolicy") final RewritePolicy rewritePolicy, 105 @PluginElement("Filter") final Filter filter) { 106 107 final boolean ignoreExceptions = Booleans.parseBoolean(ignore, true); 108 if (name == null) { 109 LOGGER.error("No name provided for RewriteAppender"); 110 return null; 111 } 112 if (appenderRefs == null) { 113 LOGGER.error("No appender references defined for RewriteAppender"); 114 return null; 115 } 116 return new RewriteAppender(name, filter, ignoreExceptions, appenderRefs, rewritePolicy, config); 117 } 118}