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    private final boolean ignoreExceptions;
036
037    private ErrorHandler handler = new DefaultErrorHandler(this);
038
039    private final Layout<? extends Serializable> layout;
040
041    private final String name;
042
043    public static int parseInt(final String s, final int defaultValue) {
044        try {
045            return Integers.parseInt(s, defaultValue);
046        } catch (final NumberFormatException e) {
047            LOGGER.error("Could not parse \"{}\" as an integer,  using default value {}: {}", s, defaultValue, e);
048            return defaultValue;
049        }
050    }
051
052    /**
053     * Constructor that defaults to suppressing exceptions.
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     */
058    protected AbstractAppender(final String name, final Filter filter, final Layout<? extends Serializable> layout) {
059        this(name, filter, layout, true);
060    }
061
062    /**
063     * Constructor.
064     * @param name The Appender name.
065     * @param filter The Filter to associate with the Appender.
066     * @param layout The layout to use to format the event.
067     * @param ignoreExceptions If true, exceptions will be logged and suppressed. If false errors will be
068     * logged and then passed to the application.
069     */
070    protected AbstractAppender(final String name, final Filter filter, final Layout<? extends Serializable> layout,
071                               final boolean ignoreExceptions) {
072        super(filter);
073        this.name = name;
074        this.layout = layout;
075        this.ignoreExceptions = ignoreExceptions;
076    }
077
078    /**
079     * Handle an error with a message.
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, and exception and a logging event.
088     * @param msg The message.
089     * @param event The LogEvent.
090     * @param t The Throwable.
091     */
092    public void error(final String msg, final LogEvent event, final Throwable t) {
093        handler.error(msg, event, t);
094    }
095
096    /**
097     * Handle an error with a message and an exception.
098     * @param msg The message.
099     * @param t The Throwable.
100     */
101    public void error(final String msg, final Throwable t) {
102        handler.error(msg, t);
103    }
104
105    /**
106     * Returns the ErrorHandler, if any.
107     * @return The ErrorHandler.
108     */
109    @Override
110    public ErrorHandler getHandler() {
111        return handler;
112    }
113
114    /**
115     * Returns the Layout for the appender.
116     * @return The Layout used to format the event.
117     */
118    @Override
119    public Layout<? extends Serializable> getLayout() {
120        return layout;
121    }
122
123    /**
124     * Returns the name of the Appender.
125     * @return The name of the Appender.
126     */
127    @Override
128    public String getName() {
129        return name;
130    }
131
132    /**
133     * Some appenders need to propagate exceptions back to the application. When {@code ignoreExceptions} is
134     * {@code false} the AppenderControl will allow the exception to percolate.
135     *
136     * @return {@code true} if exceptions will be logged but now thrown, {@code false} otherwise.
137     */
138    @Override
139    public boolean ignoreExceptions() {
140        return ignoreExceptions;
141    }
142
143    /**
144     * The handler must be set before the appender is started.
145     * @param handler The ErrorHandler to use.
146     */
147    @Override
148    public void setHandler(final ErrorHandler handler) {
149        if (handler == null) {
150            LOGGER.error("The handler cannot be set to null");
151        }
152        if (isStarted()) {
153            LOGGER.error("The handler cannot be changed once the appender is started");
154            return;
155        }
156        this.handler = handler;
157    }
158
159    @Override
160    public String toString() {
161        return name;
162    }
163
164}