    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.slf4j.impl;
    018
    019    import org.apache.logging.slf4j.Log4jLoggerFactory;
    020    import org.slf4j.ILoggerFactory;
    021    import org.slf4j.spi.LoggerFactoryBinder;
    022
    023    /**
    024     * SLF4J LoggerFactoryBinder implementation using Log4j. This class is part of the required classes used to specify an
    025     * SLF4J logger provider implementation.
    026     */
    027    public final class StaticLoggerBinder implements LoggerFactoryBinder {
    028
    029        /**
    030         * Declare the version of the SLF4J API this implementation is compiled
    031         * against. The value of this field is usually modified with each release.
    032         */
    033        // to avoid constant folding by the compiler, this field must *not* be final
    034        public static String REQUESTED_API_VERSION = "1.6"; // !final
    035
    036        private static final String LOGGER_FACTORY_CLASS_STR = Log4jLoggerFactory.class.getName();
    037
    038        /**
    039         * The unique instance of this class.
    040         */
    041        private static final StaticLoggerBinder SINGLETON = new StaticLoggerBinder();
    042
    043        /**
    044         * The ILoggerFactory instance returned by the {@link #getLoggerFactory}
    045         * method should always be the same object
    046         */
    047        private final ILoggerFactory loggerFactory;
    048
    049        /**
    050         * Private constructor to prevent instantiation
    051         */
    052        private StaticLoggerBinder() {
    053            loggerFactory = new Log4jLoggerFactory();
    054        }
    055
    056        /**
    057         * Returns the singleton of this class.
    058         *
    059         * @return the StaticLoggerBinder singleton
    060         */
    061        public static StaticLoggerBinder getSingleton() {
    062            return SINGLETON;
    063        }
    064
    065        /**
    066         * Returns the factory.
    067         * @return the factor.
    068         */
    069        @Override
    070        public ILoggerFactory getLoggerFactory() {
    071            return loggerFactory;
    072        }
    073
    074        /**
    075         * Returns the class name.
    076         * @return the class name;
    077         */
    078        @Override
    079        public String getLoggerFactoryClassStr() {
    080            return LOGGER_FACTORY_CLASS_STR;
    081        }
    082    }