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The free Java library for Asterisk PBX integration.
There is a newer version: 3.39.0
/*
 *  Copyright 2004-2006 Stefan Reuter
 *
 *  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 org.asteriskjava.util;

import org.asteriskjava.util.internal.JavaLoggingLog;
import org.asteriskjava.util.internal.Log4JLogger;
import org.asteriskjava.util.internal.NullLog;
import org.asteriskjava.util.internal.Slf4JLogger;

/**
 * Facade to hide details of the underlying logging system.
 * If you want to reuse Asterisk-Java's logging abstraction layer
 * add a private attribute to your class like this:
 * 
 * private final Log logger = LogFactory.getLog(getClass());
 * 
 * and then use the methods defined in {@link org.asteriskjava.util.Log}:
 *  * logger.error("Unable to create new instance of " + eventClass, ex);
 * 
 * Asterisk-Java's logging abstraction layer uses log4j when available
 * and falls back to java.util.logging otherwise.
 *
 * @author srt
 * @version $Id: LogFactory.java 1376 2009-10-17 00:18:50Z srt $
 */
public final class LogFactory
{
    private static Boolean slf4jLoggingAvailable = null;

    /**
     * Indicates if log4j is available on the classpath or not. If the
     * check has not yet performed this is null.
     */
    private static Boolean log4jLoggingAvailable = null;

    /**
     * Indicates if java.util.logging is available on the classpath or not. If the
     * check has not yet performed this is null.
     */
    private static Boolean javaLoggingAvailable = null;

    private static ClassLoader classLoader = LogFactory.class.getClassLoader();

    public static void setClassLoader(ClassLoader classLoader)
    {
        LogFactory.classLoader = classLoader;
    }

    /**
     * Returns an instance of Log suitable for logging from the given class.
     *
     * @param clazz the class to create the logger for.
     * @return the created logger.
     */
    public static Log getLog(Class clazz)
    {
        if (slf4jLoggingAvailable == null)
        {
            try
            {
                classLoader.loadClass("org.slf4j.Logger");
                slf4jLoggingAvailable = Boolean.TRUE;
            }
            catch (Exception e)
            {
                slf4jLoggingAvailable = Boolean.FALSE;
            }
        }

        if (slf4jLoggingAvailable)
        {
            try
            {
                return new Slf4JLogger(clazz);
            }
            catch (Throwable e)
            {
                slf4jLoggingAvailable = Boolean.FALSE;
            }
        }

        if (log4jLoggingAvailable == null)
        {
            try
            {
                classLoader.loadClass("org.apache.log4j.Logger");
                log4jLoggingAvailable = Boolean.TRUE;
            }
            catch (Exception e)
            {
                log4jLoggingAvailable = Boolean.FALSE;
            }
        }

        if (log4jLoggingAvailable)
        {
            return new Log4JLogger(clazz);
        }

        if (javaLoggingAvailable == null)
        {
            try
            {
                classLoader.loadClass("java.util.logging.Logger");
                javaLoggingAvailable = Boolean.TRUE;
            }
            catch (Exception e)
            {
                javaLoggingAvailable = Boolean.FALSE;
            }
        }
        if (javaLoggingAvailable)
        {
            return new JavaLoggingLog(clazz);
        }
        else
        {
            return new NullLog();
        }
    }
}