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 */
017package org.apache.logging.slf4j;
018
019import org.apache.logging.log4j.LogManager;
020import org.apache.logging.log4j.LoggingException;
021import org.apache.logging.log4j.spi.AbstractLoggerAdapter;
022import org.apache.logging.log4j.spi.LoggerContext;
023import org.apache.logging.log4j.util.StackLocatorUtil;
024import org.slf4j.ILoggerFactory;
025import org.slf4j.Logger;
026
027/**
028 * Log4j implementation of SLF4J ILoggerFactory interface.
029 */
030public class Log4jLoggerFactory extends AbstractLoggerAdapter<Logger> implements ILoggerFactory {
031
032    private static final String FQCN = Log4jLoggerFactory.class.getName();
033    private static final String PACKAGE = "org.slf4j";
034    private static final String TO_SLF4J_CONTEXT = "org.apache.logging.slf4j.SLF4JLoggerContext";
035
036    @Override
037    protected Logger newLogger(final String name, final LoggerContext context) {
038        final String key = Logger.ROOT_LOGGER_NAME.equals(name) ? LogManager.ROOT_LOGGER_NAME : name;
039        return new Log4jLogger(validateContext(context).getLogger(key), name);
040    }
041
042    @Override
043    protected LoggerContext getContext() {
044        final Class<?> anchor = StackLocatorUtil.getCallerClass(FQCN, PACKAGE);
045        return anchor == null ? LogManager.getContext() : getContext(StackLocatorUtil.getCallerClass(anchor));
046    }
047    private LoggerContext validateContext(final LoggerContext context) {
048        if (TO_SLF4J_CONTEXT.equals(context.getClass().getName())) {
049            throw new LoggingException("log4j-slf4j-impl cannot be present with log4j-to-slf4j");
050        }
051        return context;
052    }
053}