Apache Log4j JDK Logging Adapter is a custom implementation of java.util.logging.LogManager that uses Log4j. This adapter can be used with either the Log4j API or Log4j Core.

Bytecode (Java 8) for Apache Log4j JDK Logging Adapter is provided in a separate JAR file like log4j-jul-2.14.1.jar.

Source Code files for Apache Log4j API are provided in both binary packge like apache-log4j-2.14.1-bin.zip and source package like apache-log4j-2.14.1-src.zip. You can download them at Apache Log4j Website.

You can also browse Source Code files for Apache Log4j JDK Logging Adapter 2.14.1 below.

⏎ org/apache/logging/log4j/jul/LogManager.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements. See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.apache.logging.log4j.jul;

import java.util.Collections;
import java.util.Enumeration;
import java.util.HashSet;
import java.util.Set;
import java.util.logging.Logger;

import org.apache.logging.log4j.LoggingException;
import org.apache.logging.log4j.status.StatusLogger;
import org.apache.logging.log4j.util.LoaderUtil;
import org.apache.logging.log4j.util.PropertiesUtil;

/**
 * Log4j implementation of {@link java.util.logging.LogManager}. Note that the system property
 * {@code java.util.logging.manager} must be set to {@code org.apache.logging.log4j.jul.LogManager} in order to use
 * this adaptor. This LogManager requires the {@code log4j-api} library to be available. If {@code log4j-core} is
 * also available, then more features of {@link java.util.logging.Logger} are supported.
 *
 * <p>To override the default {@link AbstractLoggerAdapter} that is used, specify the Log4j property
 * {@code log4j.jul.LoggerAdapter} and set it to the fully qualified class name of a custom
 * implementation. All implementations must have a default constructor.</p>
 *
 * @since 2.1
 */
public class LogManager extends java.util.logging.LogManager {

    private static final org.apache.logging.log4j.Logger LOGGER = StatusLogger.getLogger();
    private final AbstractLoggerAdapter loggerAdapter;
    // Contains the set of logger names that are actively being requested using getLogger.
    private final ThreadLocal<Set<String>> recursive = ThreadLocal.withInitial(HashSet::new);

    public LogManager() {
        AbstractLoggerAdapter adapter = null;
        final String overrideAdaptorClassName =
            PropertiesUtil.getProperties().getStringProperty(Constants.LOGGER_ADAPTOR_PROPERTY);
        if (overrideAdaptorClassName != null) {
            try {
                LOGGER.info("Trying to use LoggerAdaptor [{}] specified by Log4j property.", overrideAdaptorClassName);
                adapter = LoaderUtil.newCheckedInstanceOf(overrideAdaptorClassName, AbstractLoggerAdapter.class);
            } catch (final Exception e) {
                LOGGER.error("Specified LoggerAdapter [{}] is incompatible.", overrideAdaptorClassName, e);
            }
        }
        if (adapter == null) {
            // default adapter
            String adapterClassName;
            try {
                // find out if log4j-core is available
                LoaderUtil.loadClass(Constants.CORE_LOGGER_CLASS_NAME);
                adapterClassName = Constants.CORE_LOGGER_ADAPTER_CLASS_NAME;
            } catch (final ClassNotFoundException ignored) {
                adapterClassName = Constants.API_LOGGER_ADAPTER_CLASS_NAME;
            }
            LOGGER.debug("Attempting to use {}", adapterClassName);
            try {
                adapter = LoaderUtil.newCheckedInstanceOf(adapterClassName, AbstractLoggerAdapter.class);
            } catch (final Exception e) {
                throw LOGGER.throwing(new LoggingException(e));
            }
        }
        loggerAdapter = adapter;
        LOGGER.info("Registered Log4j as the java.util.logging.LogManager.");
    }

    @Override
    public boolean addLogger(final Logger logger) {
        // in order to prevent non-bridged loggers from being registered, we always return false to indicate that
        // the named logger should be obtained through getLogger(name)
        return false;
    }

    @Override
    public Logger getLogger(final String name) {
        LOGGER.trace("Call to LogManager.getLogger({})", name);
        Set<String> activeRequests = recursive.get();
        if (activeRequests.add(name)) {
            try {
                return loggerAdapter.getLogger(name);
            } finally {
                activeRequests.remove(name);
            }
        }
        LOGGER.warn("Recursive call to getLogger for {} ignored.", name);
        return new NoOpLogger(name);
    }

    @Override
    public Enumeration<String> getLoggerNames() {
        return Collections.enumeration(loggerAdapter.getLoggersInContext(loggerAdapter.getContext()).keySet());
    }

}

⏎ org/apache/logging/log4j/jul/LogManager.java

Or download all of them as a single archive file:

File name: log4j-jul-2.14.1-sources.jar
File size: 24567 bytes
Release date: 2021-03-06
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