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;
018
019 import java.io.Serializable;
020
021 import org.apache.logging.log4j.core.Appender;
022 import org.apache.logging.log4j.core.ErrorHandler;
023 import org.apache.logging.log4j.core.Filter;
024 import org.apache.logging.log4j.core.Layout;
025 import org.apache.logging.log4j.core.LogEvent;
026 import org.apache.logging.log4j.core.filter.AbstractFilterable;
027 import org.apache.logging.log4j.core.util.Integers;
028
029 /**
030 * Abstract base class for Appenders. Although Appenders do not have to extend this class, doing so
031 * will simplify their implementation.
032 */
033 public abstract class AbstractAppender extends AbstractFilterable
034 implements Appender {
035
036 private static final long serialVersionUID = 1L;
037
038 private final boolean ignoreExceptions;
039
040 private ErrorHandler handler = new DefaultErrorHandler(this);
041
042 private final Layout<? extends Serializable> layout;
043
044 private final String name;
045
046 public static int parseInt(final String s, final int defaultValue) {
047 try {
048 return Integers.parseInt(s, defaultValue);
049 } catch (final NumberFormatException e) {
050 LOGGER.error("Could not parse \"{}\" as an integer, using default value {}: {}", s, defaultValue, e);
051 return defaultValue;
052 }
053 }
054
055 /**
056 * Constructor that defaults to suppressing exceptions.
057 * @param name The Appender name.
058 * @param filter The Filter to associate with the Appender.
059 * @param layout The layout to use to format the event.
060 */
061 protected AbstractAppender(final String name, final Filter filter, final Layout<? extends Serializable> layout) {
062 this(name, filter, layout, true);
063 }
064
065 /**
066 * Constructor.
067 * @param name The Appender name.
068 * @param filter The Filter to associate with the Appender.
069 * @param layout The layout to use to format the event.
070 * @param ignoreExceptions If true, exceptions will be logged and suppressed. If false errors will be
071 * logged and then passed to the application.
072 */
073 protected AbstractAppender(final String name, final Filter filter, final Layout<? extends Serializable> layout,
074 final boolean ignoreExceptions) {
075 super(filter);
076 this.name = name;
077 this.layout = layout;
078 this.ignoreExceptions = ignoreExceptions;
079 }
080
081 /**
082 * Handle an error with a message using the {@link ErrorHandler} configured for this Appender.
083 * @param msg The message.
084 */
085 public void error(final String msg) {
086 handler.error(msg);
087 }
088
089 /**
090 * Handle an error with a message, exception, and a logging event, using the {@link ErrorHandler} configured for
091 * this Appender.
092 * @param msg The message.
093 * @param event The LogEvent.
094 * @param t The Throwable.
095 */
096 public void error(final String msg, final LogEvent event, final Throwable t) {
097 handler.error(msg, event, t);
098 }
099
100 /**
101 * Handle an error with a message and an exception using the {@link ErrorHandler} configured for this Appender.
102 * @param msg The message.
103 * @param t The Throwable.
104 */
105 public void error(final String msg, final Throwable t) {
106 handler.error(msg, t);
107 }
108
109 /**
110 * Returns the ErrorHandler, if any.
111 * @return The ErrorHandler.
112 */
113 @Override
114 public ErrorHandler getHandler() {
115 return handler;
116 }
117
118 /**
119 * Returns the Layout for the appender.
120 * @return The Layout used to format the event.
121 */
122 @Override
123 public Layout<? extends Serializable> getLayout() {
124 return layout;
125 }
126
127 /**
128 * Returns the name of the Appender.
129 * @return The name of the Appender.
130 */
131 @Override
132 public String getName() {
133 return name;
134 }
135
136 /**
137 * Some appenders need to propagate exceptions back to the application. When {@code ignoreExceptions} is
138 * {@code false} the AppenderControl will allow the exception to percolate.
139 *
140 * @return {@code true} if exceptions will be logged but now thrown, {@code false} otherwise.
141 */
142 @Override
143 public boolean ignoreExceptions() {
144 return ignoreExceptions;
145 }
146
147 /**
148 * The handler must be set before the appender is started.
149 * @param handler The ErrorHandler to use.
150 */
151 @Override
152 public void setHandler(final ErrorHandler handler) {
153 if (handler == null) {
154 LOGGER.error("The handler cannot be set to null");
155 }
156 if (isStarted()) {
157 LOGGER.error("The handler cannot be changed once the appender is started");
158 return;
159 }
160 this.handler = handler;
161 }
162
163 @Override
164 public String toString() {
165 return name;
166 }
167
168 }