001/**
002 * Copyright (c) 2011, The University of Southampton and the individual contributors.
003 * All rights reserved.
004 *
005 * Redistribution and use in source and binary forms, with or without modification,
006 * are permitted provided that the following conditions are met:
007 *
008 *   *  Redistributions of source code must retain the above copyright notice,
009 *      this list of conditions and the following disclaimer.
010 *
011 *   *  Redistributions in binary form must reproduce the above copyright notice,
012 *      this list of conditions and the following disclaimer in the documentation
013 *      and/or other materials provided with the distribution.
014 *
015 *   *  Neither the name of the University of Southampton nor the names of its
016 *      contributors may be used to endorse or promote products derived from this
017 *      software without specific prior written permission.
018 *
019 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
020 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
021 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
022 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
023 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
024 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
025 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
026 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
027 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
028 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
029 */
030package org.openimaj.logger;
031
032import org.apache.logging.log4j.Level;
033import org.apache.logging.log4j.LogManager;
034import org.apache.logging.log4j.Logger;
035import org.apache.logging.log4j.core.Filter.Result;
036import org.apache.logging.log4j.core.appender.ConsoleAppender;
037import org.apache.logging.log4j.core.filter.ThresholdFilter;
038import org.apache.logging.log4j.core.layout.PatternLayout;
039
040/**
041 * Make using log4j slightly less awful
042 *
043 * @author Sina Samangooei (ss@ecs.soton.ac.uk)
044 *
045 */
046public class LoggerUtils {
047        /**
048         * Prepare a console logger with a default layout. This allows {@link Logger}
049         * instances to be used while still being useful as the line to prepare logger
050         * can be removed and the default log4j.properties will be correctly listened
051         * to.
052         */
053        public static void prepareConsoleLogger() {
054                final String PATTERN = "%m\n";
055                final PatternLayout layout = PatternLayout.newBuilder().withPattern(PATTERN).build();
056                final ThresholdFilter filter = ThresholdFilter.createFilter(Level.DEBUG, Result.ACCEPT, Result.DENY);
057
058                final ConsoleAppender console = ConsoleAppender.newBuilder().withName("default-consoleappender")
059                                .withLayout(layout).withFilter(filter).build();
060
061                // add appender to any Logger (here is root)
062                final Logger root = LogManager.getRootLogger();
063                if (root instanceof org.apache.logging.log4j.core.Logger)
064                        ((org.apache.logging.log4j.core.Logger) root).addAppender(console);
065        }
066
067        /**
068         * Debug message occationally
069         *
070         * @param logger
071         * @param message
072         * @param b
073         */
074        public static void debug(Logger logger, String message, boolean b) {
075                if (b) {
076                        logger.debug(message);
077                }
078        }
079
080        /**
081         * Calls {@link #format(Logger, String, Level, Object...)} with level
082         * {@link Level#DEBUG}
083         *
084         * @param logger
085         * @param string
086         * @param obj
087         */
088        public static void debugFormat(Logger logger, String string, Object... obj) {
089                format(logger, string, Level.DEBUG, obj);
090        }
091
092        /**
093         * Checks the level, if acceptable calls
094         * {@link String#format(String, Object...)} at the appropriate level
095         *
096         * @param logger
097         * @param string
098         * @param debug
099         * @param obj
100         */
101        public static void format(Logger logger, String string, Level debug, Object... obj) {
102                final Level l = logger.getLevel();
103                if (debug.isMoreSpecificThan(l)) {
104                        logger.log(debug, String.format(string, obj));
105                }
106        }
107}