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 static final long serialVersionUID = 1L; 043 044 private final Configuration config; 045 private final ConcurrentMap<String, AppenderControl> appenders = new ConcurrentHashMap<String, AppenderControl>(); 046 private final RewritePolicy rewritePolicy; 047 private final AppenderRef[] appenderRefs; 048 049 private RewriteAppender(final String name, final Filter filter, final boolean ignoreExceptions, 050 final AppenderRef[] appenderRefs, final RewritePolicy rewritePolicy, 051 final Configuration config) { 052 super(name, filter, null, ignoreExceptions); 053 this.config = config; 054 this.rewritePolicy = rewritePolicy; 055 this.appenderRefs = appenderRefs; 056 } 057 058 @Override 059 public void start() { 060 for (final AppenderRef ref : appenderRefs) { 061 final String name = ref.getRef(); 062 final Appender appender = config.getAppender(name); 063 if (appender != null) { 064 final Filter filter = appender instanceof AbstractAppender ? 065 ((AbstractAppender) appender).getFilter() : null; 066 appenders.put(name, new AppenderControl(appender, ref.getLevel(), filter)); 067 } else { 068 LOGGER.error("Appender " + ref + " cannot be located. Reference ignored"); 069 } 070 } 071 super.start(); 072 } 073 074 @Override 075 public void stop() { 076 super.stop(); 077 } 078 079 /** 080 * Modify the event and pass to the subordinate Appenders. 081 * @param event The LogEvent. 082 */ 083 @Override 084 public void append(LogEvent event) { 085 if (rewritePolicy != null) { 086 event = rewritePolicy.rewrite(event); 087 } 088 for (final AppenderControl control : appenders.values()) { 089 control.callAppender(event); 090 } 091 } 092 093 /** 094 * Create a RewriteAppender. 095 * @param name The name of the Appender. 096 * @param ignore If {@code "true"} (default) exceptions encountered when appending events are logged; otherwise 097 * they are propagated to the caller. 098 * @param appenderRefs An array of Appender names to call. 099 * @param config The Configuration. 100 * @param rewritePolicy The policy to use to modify the event. 101 * @param filter A Filter to filter events. 102 * @return The created RewriteAppender. 103 */ 104 @PluginFactory 105 public static RewriteAppender createAppender( 106 @PluginAttribute("name") final String name, 107 @PluginAttribute("ignoreExceptions") final String ignore, 108 @PluginElement("AppenderRef") final AppenderRef[] appenderRefs, 109 @PluginConfiguration final Configuration config, 110 @PluginElement("RewritePolicy") final RewritePolicy rewritePolicy, 111 @PluginElement("Filter") final Filter filter) { 112 113 final boolean ignoreExceptions = Booleans.parseBoolean(ignore, true); 114 if (name == null) { 115 LOGGER.error("No name provided for RewriteAppender"); 116 return null; 117 } 118 if (appenderRefs == null) { 119 LOGGER.error("No appender references defined for RewriteAppender"); 120 return null; 121 } 122 return new RewriteAppender(name, filter, ignoreExceptions, appenderRefs, rewritePolicy, config); 123 } 124}