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 will simplify their
031 * implementation.
032 */
033public abstract class AbstractAppender extends AbstractFilterable implements Appender {
034
035    private static final long serialVersionUID = 1L;
036
037    private final String name;
038    private final boolean ignoreExceptions;
039    private final Layout<? extends Serializable> layout;
040    private ErrorHandler handler = new DefaultErrorHandler(this);
041
042    /**
043     * Constructor that defaults to suppressing exceptions.
044     * 
045     * @param name The Appender name.
046     * @param filter The Filter to associate with the Appender.
047     * @param layout The layout to use to format the event.
048     */
049    protected AbstractAppender(final String name, final Filter filter, final Layout<? extends Serializable> layout) {
050        this(name, filter, layout, true);
051    }
052
053    /**
054     * Constructor.
055     * 
056     * @param name The Appender name.
057     * @param filter The Filter to associate with the Appender.
058     * @param layout The layout to use to format the event.
059     * @param ignoreExceptions If true, exceptions will be logged and suppressed. If false errors will be logged and
060     *            then passed to the application.
061     */
062    protected AbstractAppender(final String name, final Filter filter, final Layout<? extends Serializable> layout,
063            final boolean ignoreExceptions) {
064        super(filter);
065        this.name = name;
066        this.layout = layout;
067        this.ignoreExceptions = ignoreExceptions;
068    }
069
070    public static int parseInt(final String s, final int defaultValue) {
071        try {
072            return Integers.parseInt(s, defaultValue);
073        } catch (final NumberFormatException e) {
074            LOGGER.error("Could not parse \"{}\" as an integer,  using default value {}: {}", s, defaultValue, e);
075            return defaultValue;
076        }
077    }
078
079    /**
080     * Handle an error with a message using the {@link ErrorHandler} configured for this Appender.
081     * 
082     * @param msg The message.
083     */
084    public void error(final String msg) {
085        handler.error(msg);
086    }
087
088    /**
089     * Handle an error with a message, exception, and a logging event, using the {@link ErrorHandler} configured for
090     * this Appender.
091     * 
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     * 
103     * @param msg The message.
104     * @param t The Throwable.
105     */
106    public void error(final String msg, final Throwable t) {
107        handler.error(msg, t);
108    }
109
110    /**
111     * Returns the ErrorHandler, if any.
112     * 
113     * @return The ErrorHandler.
114     */
115    @Override
116    public ErrorHandler getHandler() {
117        return handler;
118    }
119
120    /**
121     * Returns the Layout for the appender.
122     * 
123     * @return The Layout used to format the event.
124     */
125    @Override
126    public Layout<? extends Serializable> getLayout() {
127        return layout;
128    }
129
130    /**
131     * Returns the name of the Appender.
132     * 
133     * @return The name of the Appender.
134     */
135    @Override
136    public String getName() {
137        return name;
138    }
139
140    /**
141     * Some appenders need to propagate exceptions back to the application. When {@code ignoreExceptions} is
142     * {@code false} the AppenderControl will allow the exception to percolate.
143     *
144     * @return {@code true} if exceptions will be logged but now thrown, {@code false} otherwise.
145     */
146    @Override
147    public boolean ignoreExceptions() {
148        return ignoreExceptions;
149    }
150
151    /**
152     * The handler must be set before the appender is started.
153     * 
154     * @param handler The ErrorHandler to use.
155     */
156    @Override
157    public void setHandler(final ErrorHandler handler) {
158        if (handler == null) {
159            LOGGER.error("The handler cannot be set to null");
160        }
161        if (isStarted()) {
162            LOGGER.error("The handler cannot be changed once the appender is started");
163            return;
164        }
165        this.handler = handler;
166    }
167
168    @Override
169    public String toString() {
170        return name;
171    }
172
173}