kieker.common.logging.LogFactory.java Source code

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Here is the source code for kieker.common.logging.LogFactory.java

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/***************************************************************************
 * Copyright 2015 Kieker Project (http://kieker-monitoring.net)
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 ***************************************************************************/

package kieker.common.logging;

import java.util.Locale;

/**
 * This factory class should be used to get new logger instances. It initializes the logging system based on the available classes.
 * 
 * @author Jan Waller
 * 
 * @since 1.5
 */
public final class LogFactory { // NOPMD (Implementation of an logger)

    /** This constant should point to the fully qualified class name of the custom JVM logger. */
    public static final String CUSTOM_LOGGER_JVM = "kieker.common.logging.Log";

    private static final String JVM_LOGGER;
    private static final Logger DETECTED_LOGGER;

    private static enum Logger {
        NONE, JDK, COMMONS, SLF4J, WEBGUI, JUNIT,
    }

    static {
        final String systemPropertyLogger = System.getProperty(CUSTOM_LOGGER_JVM);
        if (null != systemPropertyLogger) {
            JVM_LOGGER = systemPropertyLogger.trim().toUpperCase(Locale.US);
        } else {
            JVM_LOGGER = null;
        }
        DETECTED_LOGGER = LogFactory.detectLogger();
        final Log log = LogFactory.getLog(LogFactory.class);
        if ((null != JVM_LOGGER) && !DETECTED_LOGGER.name().equals(JVM_LOGGER)) {
            log.warn("Failed to load Logger with property " + CUSTOM_LOGGER_JVM + "=" + JVM_LOGGER + ", using "
                    + DETECTED_LOGGER.name() + " instead.");
        }
        // System.out.println(DETECTED_LOGGER.toString());
        if (log.isDebugEnabled()) {
            log.debug(DETECTED_LOGGER.toString());
        }
    }

    /**
     * Private constructor to avoid instantiation.
     */
    private LogFactory() {
        // Nothing to do
    }

    /**
     * Delivers the log for the given class or creates a new one if it doesn't exist already.
     * 
     * @param clazz
     *            The corresponding class.
     * 
     * @return A logger for the given class.
     */
    public static final Log getLog(final Class<?> clazz) {
        return LogFactory.getLog(clazz.getName());
    }

    /**
     * Delivers the log for the given name or creates a new one if it doesn't exist already.
     * 
     * @param name
     *            The corresponding name.
     * 
     * @return A logger for the given name.
     */
    public static final Log getLog(final String name) {
        switch (DETECTED_LOGGER) { // NOPMD (no break needed)
        case NONE:
            return new LogImplNone(name);
        case JDK:
            return new LogImplJDK14(name);
        case COMMONS:
            return new LogImplCommonsLogging(name);
        case SLF4J:
            return new LogImplSLF4JLogging(name);
        case WEBGUI:
            return new LogImplWebguiLogging(name);
        case JUNIT:
            return new LogImplJUnit(name);
        default:
            return new LogImplJDK14(name);
        }
    }

    /**
     * This method tries to detect the available loggers.
     * 
     * @return The found logger.
     */
    private static final Logger detectLogger() {
        if (null != JVM_LOGGER) {
            try {
                return Enum.valueOf(Logger.class, JVM_LOGGER);
            } catch (final IllegalArgumentException ex) { // NOPMD NOCS
                // Notify is handled above.
            }
        }
        try {
            if (Class.forName("org.slf4j.impl.StaticLoggerBinder") != null) {
                return Logger.SLF4J; // use SLF4J logging
            }
        } catch (final Exception ex) { // NOPMD NOCS (catch Exception)
            // use default in case of errors ...
        }
        try {
            if (Class.forName("org.apache.commons.logging.Log") != null) {
                return Logger.COMMONS; // use commons logging
            }
        } catch (final Exception ex) { // NOPMD NOCS (catch Exception)
            // use default in case of errors ...
        }
        return Logger.JDK;
    }
}