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 final String name;
036    private final boolean ignoreExceptions;
037    private final Layout<? extends Serializable> layout;
038    private ErrorHandler handler = new DefaultErrorHandler(this);
039
040    /**
041     * Constructor that defaults to suppressing exceptions.
042     * 
043     * @param name The Appender name.
044     * @param filter The Filter to associate with the Appender.
045     * @param layout The layout to use to format the event.
046     */
047    protected AbstractAppender(final String name, final Filter filter, final Layout<? extends Serializable> layout) {
048        this(name, filter, layout, true);
049    }
050
051    /**
052     * Constructor.
053     * 
054     * @param name The Appender name.
055     * @param filter The Filter to associate with the Appender.
056     * @param layout The layout to use to format the event.
057     * @param ignoreExceptions If true, exceptions will be logged and suppressed. If false errors will be logged and
058     *            then passed to the application.
059     */
060    protected AbstractAppender(final String name, final Filter filter, final Layout<? extends Serializable> layout,
061            final boolean ignoreExceptions) {
062        super(filter);
063        this.name = name;
064        this.layout = layout;
065        this.ignoreExceptions = ignoreExceptions;
066    }
067
068    public static int parseInt(final String s, final int defaultValue) {
069        try {
070            return Integers.parseInt(s, defaultValue);
071        } catch (final NumberFormatException e) {
072            LOGGER.error("Could not parse \"{}\" as an integer,  using default value {}: {}", s, defaultValue, e);
073            return defaultValue;
074        }
075    }
076
077    /**
078     * Handle an error with a message using the {@link ErrorHandler} configured for this Appender.
079     * 
080     * @param msg The message.
081     */
082    public void error(final String msg) {
083        handler.error(msg);
084    }
085
086    /**
087     * Handle an error with a message, exception, and a logging event, using the {@link ErrorHandler} configured for
088     * this Appender.
089     * 
090     * @param msg The message.
091     * @param event The LogEvent.
092     * @param t The Throwable.
093     */
094    public void error(final String msg, final LogEvent event, final Throwable t) {
095        handler.error(msg, event, t);
096    }
097
098    /**
099     * Handle an error with a message and an exception using the {@link ErrorHandler} configured for this Appender.
100     * 
101     * @param msg The message.
102     * @param t The Throwable.
103     */
104    public void error(final String msg, final Throwable t) {
105        handler.error(msg, t);
106    }
107
108    /**
109     * Returns the ErrorHandler, if any.
110     * 
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     * 
121     * @return The Layout used to format the event.
122     */
123    @Override
124    public Layout<? extends Serializable> getLayout() {
125        return layout;
126    }
127
128    /**
129     * Returns the name of the Appender.
130     * 
131     * @return The name of the Appender.
132     */
133    @Override
134    public String getName() {
135        return name;
136    }
137
138    /**
139     * Some appenders need to propagate exceptions back to the application. When {@code ignoreExceptions} is
140     * {@code false} the AppenderControl will allow the exception to percolate.
141     *
142     * @return {@code true} if exceptions will be logged but now thrown, {@code false} otherwise.
143     */
144    @Override
145    public boolean ignoreExceptions() {
146        return ignoreExceptions;
147    }
148
149    /**
150     * The handler must be set before the appender is started.
151     * 
152     * @param handler The ErrorHandler to use.
153     */
154    @Override
155    public void setHandler(final ErrorHandler handler) {
156        if (handler == null) {
157            LOGGER.error("The handler cannot be set to null");
158        }
159        if (isStarted()) {
160            LOGGER.error("The handler cannot be changed once the appender is started");
161            return;
162        }
163        this.handler = handler;
164    }
165
166    @Override
167    public String toString() {
168        return name;
169    }
170
171}