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;
018
019import java.io.Serializable;
020
021import org.apache.logging.log4j.core.Appender;
022import org.apache.logging.log4j.core.ErrorHandler;
023import org.apache.logging.log4j.core.Filter;
024import org.apache.logging.log4j.core.Layout;
025import org.apache.logging.log4j.core.LogEvent;
026import org.apache.logging.log4j.core.filter.AbstractFilterable;
027import 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 */
033public 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}