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.Map; 020import java.util.concurrent.ConcurrentHashMap; 021import java.util.concurrent.ConcurrentMap; 022 023import org.apache.logging.log4j.core.Appender; 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.helpers.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", elementType = "appender", printObject = true) 041public final class RewriteAppender extends AbstractAppender { 042 private final Configuration config; 043 private final ConcurrentMap<String, AppenderControl> appenders = new ConcurrentHashMap<String, AppenderControl>(); 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 final Map<String, Appender> map = config.getAppenders(); 059 for (final AppenderRef ref : appenderRefs) { 060 final String name = ref.getRef(); 061 final Appender appender = map.get(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 @Override 074 public void stop() { 075 super.stop(); 076 } 077 078 /** 079 * Modify the event and pass to the subordinate Appenders. 080 * @param event The LogEvent. 081 */ 082 @Override 083 public void append(LogEvent event) { 084 if (rewritePolicy != null) { 085 event = rewritePolicy.rewrite(event); 086 } 087 for (final AppenderControl control : appenders.values()) { 088 control.callAppender(event); 089 } 090 } 091 092 /** 093 * Create a RewriteAppender. 094 * @param name The name of the Appender. 095 * @param ignore If {@code "true"} (default) exceptions encountered when appending events are logged; otherwise 096 * they are propagated to the caller. 097 * @param appenderRefs An array of Appender names to call. 098 * @param config The Configuration. 099 * @param rewritePolicy The policy to use to modify the event. 100 * @param filter A Filter to filter events. 101 * @return The created RewriteAppender. 102 */ 103 @PluginFactory 104 public static RewriteAppender createAppender( 105 @PluginAttribute("name") final String name, 106 @PluginAttribute("ignoreExceptions") final String ignore, 107 @PluginElement("AppenderRef") final AppenderRef[] appenderRefs, 108 @PluginConfiguration final Configuration config, 109 @PluginElement("RewritePolicy") final RewritePolicy rewritePolicy, 110 @PluginElement("Filter") final Filter filter) { 111 112 final boolean ignoreExceptions = Booleans.parseBoolean(ignore, true); 113 if (name == null) { 114 LOGGER.error("No name provided for RewriteAppender"); 115 return null; 116 } 117 if (appenderRefs == null) { 118 LOGGER.error("No appender references defined for RewriteAppender"); 119 return null; 120 } 121 return new RewriteAppender(name, filter, ignoreExceptions, appenderRefs, rewritePolicy, config); 122 } 123}