log4j.java

jxta官方例程

/*
*  Copyright (c) 2001 Sun Microsystems, Inc.  All rights
*  reserved.
*
*  Redistribution and use in source and binary forms, with or without
*  modification, are permitted provided that the following conditions
*  are met:
*
*  1. Redistributions of source code must retain the above copyright
*  notice, this list of conditions and the following disclaimer.
*
*  2. Redistributions in binary form must reproduce the above copyright
*  notice, this list of conditions and the following disclaimer in
*  the documentation and/or other materials provided with the
*  distribution.
*
*  3. The end-user documentation included with the redistribution,
*  if any, must include the following acknowledgment:
*  "This product includes software developed by the
*  Sun Microsystems, Inc. for Project JXTA."
*  Alternately, this acknowledgment may appear in the software itself,
*  if and wherever such third-party acknowledgments normally appear.
*
*  4. The names "Sun", "Sun Microsystems, Inc.", "JXTA" and "Project JXTA"
*  must not be used to endorse or promote products derived from this
*  software without prior written permission. For written
*  permission, please contact Project JXTA at http://www.jxta.org.
*
*  5. Products derived from this software may not be called "JXTA",
*  nor may "JXTA" appear in their name, without prior written
*  permission of Sun.
*
*  THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
*  WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
*  OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
*  DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
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*  LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
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*  ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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*  OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
*  SUCH DAMAGE.
*  ====================================================================
*
*  This software consists of voluntary contributions made by many
*  individuals on behalf of Project JXTA.  For more
*  information on Project JXTA, please see
*  <http://www.jxta.org/>.
*
*  This license is based on the BSD license adopted by the Apache Foundation.
*
*  $Id: Log4J.java,v 1.4 2006/05/17 19:38:28 nano Exp $
*/

package net.jxta.myjxta.util;

import org.apache.log4j.BasicConfigurator;
import org.apache.log4j.Level;
import org.apache.log4j.Logger;
import org.apache.log4j.Priority;
import org.apache.log4j.PropertyConfigurator;
import org.apache.log4j.helpers.FileWatchdog;
import org.apache.log4j.net.SyslogAppender;
import org.apache.log4j.xml.DOMConfigurator;

/**
 *
 * @version $Id: Log4J.java,v 1.4 2006/05/17 19:38:28 nano Exp $
 *
 * @author james todd [gonzo at jxta dot org]
 * @author mike mcangus [mcangus at jxta dot org]
 */

public class Log4J {
    private static Logger LOG = null;
    private static boolean alreadyConfigured = false;
//    private static final HashMap formatterMap = new HashMap();

    /**
     * Provides a Log4J {@link org.apache.log4j.Level Level} that always logs unless logging is completely turned off.
     */
    public static final Level STATUS_LEVEL = new MyLevel(Priority.FATAL_INT + 10, "STATUS", SyslogAppender.LOG_LOCAL0);

    private Log4J() {
        // private constructor to ensure that this class is not instantiated.
    }

    /**
     * Configures Log4J logging.
     * <p>
     * Attempts to use ConfigureAndWatch capabilities of the relevant
     * {@link org.apache.log4j.spi.Configurator} class.
     * <p>
     * Looks first for log4j.properties, then for log4j.xml file to define the configuration.
     * If neither file is found, then the default configuration from
     * {@link org.apache.log4j.BasicConfigurator#configure() BasicConfigurator.configure()}
     * is used.  Uses {@link Env#getLog4jConfigFilePath()} to locate the configuration file.
     * <p>
     * By default the configuration file (assuming one is found) is checked for updates every 60 seconds.
     * This can be modified by using the the runtime parameter -Dlog4j.config.watchSeconds=&lt;seconds&gt;.
     */
    public static void initialize() {
        if (alreadyConfigured) {
            if (LOG.isEnabledFor(Level.DEBUG)) {
                LOG.debug("Log4J has already been configured");
            }
            return;
        }

        String log4jConfigWatchSecondsString = System.getProperty("log4j.config.watchSeconds");

        if ((log4jConfigWatchSecondsString == null ) || (log4jConfigWatchSecondsString.length() == 0)) {
            configureAndWatch(FileWatchdog.DEFAULT_DELAY);   // Use default (60 seconds at the time of this comment)
        } else {
            try {
                long log4jConfigWatchMillisecs = Long.parseLong(log4jConfigWatchSecondsString) * 1000L;
                configureAndWatch(log4jConfigWatchMillisecs);
            }  catch (NumberFormatException e) { // log4jConfigWatchMillisecs is not a long
                configureAndWatch(FileWatchdog.DEFAULT_DELAY);  // Use default (60 seconds at the time of this comment)
                LOG.warn("Received invalid log4j.config.watchSeconds from System.getProperty(): \"" +
                         log4jConfigWatchSecondsString + "\"", e);
                LOG.warn("Using default: " + FileWatchdog.DEFAULT_DELAY + " ms");
            }
        }
        alreadyConfigured = true;
        if (LOG.isEnabledFor(Level.DEBUG)) {
            LOG.debug("Log4J configureAndWatch setup complete");
        }
    }


//    /**
//     * Returns a message to be logged for the default locale.
//     *
//     * @param messageId Identifies the message in the log4jText bundle.
//     * @return the formatted message
//     *
//     * @deprecated
//     */
//    public static String formatMessage(String messageId) {
//        return formatMessage(messageId, Locale.getDefault(), new Object[]{});
//    }


//    /**
//     * Returns a message to be logged for the supplied locale.
//     *
//     * @param messageId Identifies the message in the log4jText bundle.
//     * @param locale The locale to be used for localized messages.
//     * @return the formatted message
//     *
//     * @deprecated
//     */
//    public static String formatMessage(String messageId, Locale locale) {
//        return formatMessage(messageId, locale, new Object[]{});
//    }

//    /**
//     * Returns a message to be logged for the default locale.
//     *
//     * @param messageId Identifies the message in the log4jText bundle.
//     * @param parms Parameters to be substituted into the message.
//     * @return the formatted message
//     *
//     * @deprecated
//     */
//    public static String formatMessage(String messageId, Object[] parms) {
//        return formatMessage(messageId, Locale.getDefault(), parms);
//    }

//    /**
//     * Returns a message to be logged for the supplied locale.
//     *
//     * @param messageId Identifies the message in the log4jText bundle.
//     * @param locale The locale to be used for localized messages.
//     * @param parms Parameters to be substituted into the message.
//     * @return the formatted message
//     *
//     * @deprecated
//     */
//    public static String formatMessage(String messageId, Locale locale, Object[] parms) {
//        ResourceBundle messages = ResourceBundle.getBundle(Constants.LOG4J_BUNDLE,locale);
//
//        String message = messages.getString(messageId);
//        if ((parms == null) || (parms.length == 0)) {
//            return message;
//        } else {
//            MessageFormat formatter = (MessageFormat)formatterMap.get(locale);
//
//            if (formatter == null) {
//                formatter = new MessageFormat("",locale);
//                formatterMap.put(locale, formatter);
//            }
//
//            formatter.applyPattern(message);
//            return formatter.format(parms);
//        }
//    }

    private static void configureAndWatch(long watchMillisecs) {
        String log4jConfigFile = Env.getLog4jConfigFilePath();
        
        if (log4jConfigFile != null) {
            if (Env.isLog4jConfigFileXml()) {
                DOMConfigurator.configureAndWatch(log4jConfigFile, watchMillisecs);
            } else {
                PropertyConfigurator.configureAndWatch(log4jConfigFile, watchMillisecs);
            }
            LOG = Logger.getLogger(Log4J.class);
            if (LOG.isEnabledFor(Level.DEBUG)) {
                LOG.debug("Log4J configured with config file " + log4jConfigFile);
            }
        } else {
            // Since we aren't going to be able to pull our "real" settings, let's at least make sure we get some output 
            BasicConfigurator.configure();
            LOG = Logger.getLogger(Log4J.class);
            // Log an error with detail regarding the problem (and suspected cause)
            LOG.error("Unable to find either log4j.xml or log4j.properties files in the classpath");
        }
    }

    private static class MyLevel extends Level {
        private MyLevel(int level, String name, int sysLogLevel) {
            super(level, name, sysLogLevel);
        }
    }
}