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