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 */ 017 package org.apache.logging.log4j.core.appender.rewrite; 018 019 import org.apache.logging.log4j.core.Appender; 020 import org.apache.logging.log4j.core.Filter; 021 import org.apache.logging.log4j.core.LogEvent; 022 import org.apache.logging.log4j.core.appender.AbstractAppender; 023 import org.apache.logging.log4j.core.config.AppenderControl; 024 import org.apache.logging.log4j.core.config.AppenderRef; 025 import org.apache.logging.log4j.core.config.Configuration; 026 import org.apache.logging.log4j.core.config.plugins.Plugin; 027 import org.apache.logging.log4j.core.config.plugins.PluginAttr; 028 import org.apache.logging.log4j.core.config.plugins.PluginConfiguration; 029 import org.apache.logging.log4j.core.config.plugins.PluginElement; 030 import org.apache.logging.log4j.core.config.plugins.PluginFactory; 031 032 import java.io.Serializable; 033 import java.util.Map; 034 import java.util.concurrent.ConcurrentHashMap; 035 import java.util.concurrent.ConcurrentMap; 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) 041 public final class RewriteAppender<T extends Serializable> extends AbstractAppender<T> { 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 handleException, 048 final AppenderRef[] appenderRefs, final RewritePolicy rewritePolicy, 049 final Configuration config) { 050 super(name, filter, null, handleException); 051 this.config = config; 052 this.rewritePolicy = rewritePolicy; 053 this.appenderRefs = appenderRefs; 054 } 055 056 @Override 057 @SuppressWarnings("unchecked") 058 public void start() { 059 final Map<String, Appender<?>> map = config.getAppenders(); 060 for (final AppenderRef ref : appenderRefs) { 061 final String name = ref.getRef(); 062 final Appender appender = map.get(name); 063 if (appender != null) { 064 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 suppress If true, exceptions will be handled in the Appender. 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 <S extends Serializable> RewriteAppender<S> createAppender(@PluginAttr("name") final String name, 105 @PluginAttr("suppressExceptions") final String suppress, 106 @PluginElement("appender-ref") final AppenderRef[] appenderRefs, 107 @PluginConfiguration final Configuration config, 108 @PluginElement("rewritePolicy") final RewritePolicy rewritePolicy, 109 @PluginElement("filter") final Filter filter) { 110 111 final boolean handleExceptions = suppress == null ? true : Boolean.valueOf(suppress); 112 113 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<S>(name, filter, handleExceptions, appenderRefs, rewritePolicy, config); 122 } 123 }