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.helpers.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    /**
044     * Appenders set this by calling super.start().
045     */
046    private boolean started = false;
047
048    public static int parseInt(String s, int defaultValue) {
049        try {
050            return Integers.parseInt(s, defaultValue);
051        } catch (NumberFormatException e) {
052            LOGGER.error("Could not parse \"{}\" as an integer,  using default value {}: {}", s, defaultValue, e);
053            return defaultValue;
054        }
055    }
056
057    /**
058     * Constructor that defaults to suppressing exceptions.
059     * @param name The Appender name.
060     * @param filter The Filter to associate with the Appender.
061     * @param layout The layout to use to format the event.
062     */
063    protected AbstractAppender(final String name, final Filter filter, final Layout<? extends Serializable> layout) {
064        this(name, filter, layout, true);
065    }
066
067    /**
068     * Constructor.
069     * @param name The Appender name.
070     * @param filter The Filter to associate with the Appender.
071     * @param layout The layout to use to format the event.
072     * @param ignoreExceptions If true, exceptions will be logged and suppressed. If false errors will be
073     * logged and then passed to the application.
074     */
075    protected AbstractAppender(final String name, final Filter filter, final Layout<? extends Serializable> layout,
076                               final boolean ignoreExceptions) {
077        super(filter);
078        this.name = name;
079        this.layout = layout;
080        this.ignoreExceptions = ignoreExceptions;
081    }
082
083    /**
084     * Handle an error with a message.
085     * @param msg The message.
086     */
087    public void error(final String msg) {
088        handler.error(msg);
089    }
090
091    /**
092     * Handle an error with a message, and exception and a logging event.
093     * @param msg The message.
094     * @param event The LogEvent.
095     * @param t The Throwable.
096     */
097    public void error(final String msg, final LogEvent event, final Throwable t) {
098        handler.error(msg, event, t);
099    }
100
101    /**
102     * Handle an error with a message and an exception.
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     * @return The ErrorHandler.
113     */
114    @Override
115    public ErrorHandler getHandler() {
116        return handler;
117    }
118
119    /**
120     * Returns the Layout for the appender.
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     * @return The name of the Appender.
131     */
132    @Override
133    public String getName() {
134        return name;
135    }
136
137    /**
138     * Some appenders need to propagate exceptions back to the application. When {@code ignoreExceptions} is
139     * {@code false} the AppenderControl will allow the exception to percolate.
140     *
141     * @return {@code true} if exceptions will be logged but now thrown, {@code false} otherwise.
142     */
143    @Override
144    public boolean ignoreExceptions() {
145        return ignoreExceptions;
146    }
147
148    /**
149     * Returns true if the Appender is started, false otherwise.
150     * @return true if the Appender is started, false otherwise.
151     */
152    @Override
153    public boolean isStarted() {
154        return started;
155    }
156
157    /**
158     * The handler must be set before the appender is started.
159     * @param handler The ErrorHandler to use.
160     */
161    @Override
162    public void setHandler(final ErrorHandler handler) {
163        if (handler == null) {
164            LOGGER.error("The handler cannot be set to null");
165        }
166        if (isStarted()) {
167            LOGGER.error("The handler cannot be changed once the appender is started");
168            return;
169        }
170        this.handler = handler;
171    }
172
173    /**
174     * Start the Appender.
175     */
176    @Override
177    public void start() {
178        startFilter();
179        this.started = true;
180    }
181
182    /**
183     * Stop the Appender.
184     */
185    @Override
186    public void stop() {
187        this.started = false;
188        stopFilter();
189    }
190
191    @Override
192    public String toString() {
193        return name;
194    }
195
196}