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 java.util.concurrent.ConcurrentHashMap;
020 import java.util.concurrent.ConcurrentMap;
021
022 import org.apache.logging.log4j.core.Appender;
023 import org.apache.logging.log4j.core.Filter;
024 import org.apache.logging.log4j.core.LogEvent;
025 import org.apache.logging.log4j.core.appender.AbstractAppender;
026 import org.apache.logging.log4j.core.config.AppenderControl;
027 import org.apache.logging.log4j.core.config.AppenderRef;
028 import org.apache.logging.log4j.core.config.Configuration;
029 import org.apache.logging.log4j.core.config.plugins.Plugin;
030 import org.apache.logging.log4j.core.config.plugins.PluginAttribute;
031 import org.apache.logging.log4j.core.config.plugins.PluginConfiguration;
032 import org.apache.logging.log4j.core.config.plugins.PluginElement;
033 import org.apache.logging.log4j.core.config.plugins.PluginFactory;
034 import 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)
040 public 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 }