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.Property; 031import org.apache.logging.log4j.core.config.plugins.Plugin; 032import org.apache.logging.log4j.core.config.plugins.PluginAttribute; 033import org.apache.logging.log4j.core.config.plugins.PluginConfiguration; 034import org.apache.logging.log4j.core.config.plugins.PluginElement; 035import org.apache.logging.log4j.core.config.plugins.PluginFactory; 036import org.apache.logging.log4j.core.util.Booleans; 037 038/** 039 * This Appender allows the logging event to be manipulated before it is processed by other Appenders. 040 */ 041@Plugin(name = "Rewrite", category = Core.CATEGORY_NAME, elementType = Appender.ELEMENT_TYPE, printObject = true) 042public final class RewriteAppender extends AbstractAppender { 043 044 private final Configuration config; 045 private final ConcurrentMap<String, AppenderControl> appenders = new ConcurrentHashMap<>(); 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, final Property[] properties) { 052 super(name, filter, null, ignoreExceptions, properties); 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 /** 075 * Modifies the event and pass to the subordinate Appenders. 076 * @param event The LogEvent. 077 */ 078 @Override 079 public void append(LogEvent event) { 080 if (rewritePolicy != null) { 081 event = rewritePolicy.rewrite(event); 082 } 083 for (final AppenderControl control : appenders.values()) { 084 control.callAppender(event); 085 } 086 } 087 088 /** 089 * Creates a RewriteAppender. 090 * @param name The name of the Appender. 091 * @param ignore If {@code "true"} (default) exceptions encountered when appending events are logged; otherwise 092 * they are propagated to the caller. 093 * @param appenderRefs An array of Appender names to call. 094 * @param config The Configuration. 095 * @param rewritePolicy The policy to use to modify the event. 096 * @param filter A Filter to filter events. 097 * @return The created RewriteAppender. 098 */ 099 @PluginFactory 100 public static RewriteAppender createAppender( 101 @PluginAttribute("name") final String name, 102 @PluginAttribute("ignoreExceptions") final String ignore, 103 @PluginElement("AppenderRef") final AppenderRef[] appenderRefs, 104 @PluginConfiguration final Configuration config, 105 @PluginElement("RewritePolicy") final RewritePolicy rewritePolicy, 106 @PluginElement("Filter") final Filter filter) { 107 108 final boolean ignoreExceptions = Booleans.parseBoolean(ignore, true); 109 if (name == null) { 110 LOGGER.error("No name provided for RewriteAppender"); 111 return null; 112 } 113 if (appenderRefs == null) { 114 LOGGER.error("No appender references defined for RewriteAppender"); 115 return null; 116 } 117 return new RewriteAppender(name, filter, ignoreExceptions, appenderRefs, rewritePolicy, config, null); 118 } 119}