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.Filter; 024import org.apache.logging.log4j.core.LogEvent; 025import org.apache.logging.log4j.core.appender.AbstractAppender; 026import org.apache.logging.log4j.core.config.AppenderControl; 027import org.apache.logging.log4j.core.config.AppenderRef; 028import org.apache.logging.log4j.core.config.Configuration; 029import org.apache.logging.log4j.core.config.plugins.Plugin; 030import org.apache.logging.log4j.core.config.plugins.PluginAttribute; 031import org.apache.logging.log4j.core.config.plugins.PluginConfiguration; 032import org.apache.logging.log4j.core.config.plugins.PluginElement; 033import org.apache.logging.log4j.core.config.plugins.PluginFactory; 034import org.apache.logging.log4j.core.util.Booleans; 035 036/** 037 * This Appender allows the logging event to be manipulated before it is processed by other Appenders. 038 */ 039@Plugin(name = "Rewrite", category = "Core", elementType = "appender", printObject = true) 040public final class RewriteAppender extends AbstractAppender { 041 042 private final Configuration config; 043 private final ConcurrentMap<String, AppenderControl> appenders = new ConcurrentHashMap<>(); 044 private final RewritePolicy rewritePolicy; 045 private final AppenderRef[] appenderRefs; 046 047 private RewriteAppender(final String name, final Filter filter, final boolean ignoreExceptions, 048 final AppenderRef[] appenderRefs, final RewritePolicy rewritePolicy, 049 final Configuration config) { 050 super(name, filter, null, ignoreExceptions); 051 this.config = config; 052 this.rewritePolicy = rewritePolicy; 053 this.appenderRefs = appenderRefs; 054 } 055 056 @Override 057 public void start() { 058 for (final AppenderRef ref : appenderRefs) { 059 final String name = ref.getRef(); 060 final Appender appender = config.getAppender(name); 061 if (appender != null) { 062 final Filter filter = appender instanceof AbstractAppender ? 063 ((AbstractAppender) appender).getFilter() : null; 064 appenders.put(name, new AppenderControl(appender, ref.getLevel(), filter)); 065 } else { 066 LOGGER.error("Appender " + ref + " cannot be located. Reference ignored"); 067 } 068 } 069 super.start(); 070 } 071 072 @Override 073 public void stop() { 074 super.stop(); 075 } 076 077 /** 078 * Modifies the event and pass to the subordinate Appenders. 079 * @param event The LogEvent. 080 */ 081 @Override 082 public void append(LogEvent event) { 083 if (rewritePolicy != null) { 084 event = rewritePolicy.rewrite(event); 085 } 086 for (final AppenderControl control : appenders.values()) { 087 control.callAppender(event); 088 } 089 } 090 091 /** 092 * Creates a RewriteAppender. 093 * @param name The name of the Appender. 094 * @param ignore If {@code "true"} (default) exceptions encountered when appending events are logged; otherwise 095 * they are propagated to the caller. 096 * @param appenderRefs An array of Appender names to call. 097 * @param config The Configuration. 098 * @param rewritePolicy The policy to use to modify the event. 099 * @param filter A Filter to filter events. 100 * @return The created RewriteAppender. 101 */ 102 @PluginFactory 103 public static RewriteAppender createAppender( 104 @PluginAttribute("name") final String name, 105 @PluginAttribute("ignoreExceptions") final String ignore, 106 @PluginElement("AppenderRef") final AppenderRef[] appenderRefs, 107 @PluginConfiguration final Configuration config, 108 @PluginElement("RewritePolicy") final RewritePolicy rewritePolicy, 109 @PluginElement("Filter") final Filter filter) { 110 111 final boolean ignoreExceptions = Booleans.parseBoolean(ignore, true); 112 if (name == null) { 113 LOGGER.error("No name provided for RewriteAppender"); 114 return null; 115 } 116 if (appenderRefs == null) { 117 LOGGER.error("No appender references defined for RewriteAppender"); 118 return null; 119 } 120 return new RewriteAppender(name, filter, ignoreExceptions, appenderRefs, rewritePolicy, config); 121 } 122}