Apache Log4j Core Implementation provides the functional components of the logging system. Users are free to create their own plugins and include them in the logging configuration. Apache Log4j Core is a required module to use Apache Log4j.

Bytecode (Java 8) for Apache Log4j Core Implementation is provided in a separate JAR file like log4j-core-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 Core Implementation 2.14.1 below.

⏎ org/apache/logging/log4j/core/config/composite/CompositeConfiguration.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.core.config.composite;

import java.lang.reflect.InvocationTargetException;
import java.net.URI;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Map;

import org.apache.logging.log4j.Level;
import org.apache.logging.log4j.core.config.AbstractConfiguration;
import org.apache.logging.log4j.core.config.Configuration;
import org.apache.logging.log4j.core.config.ConfigurationFactory;
import org.apache.logging.log4j.core.config.ConfigurationSource;
import org.apache.logging.log4j.core.config.Node;
import org.apache.logging.log4j.core.config.Reconfigurable;
import org.apache.logging.log4j.core.config.plugins.util.ResolverUtil;
import org.apache.logging.log4j.core.config.status.StatusConfiguration;
import org.apache.logging.log4j.core.util.Loader;
import org.apache.logging.log4j.core.util.Patterns;
import org.apache.logging.log4j.core.util.Source;
import org.apache.logging.log4j.core.util.WatchManager;
import org.apache.logging.log4j.core.util.Watcher;
import org.apache.logging.log4j.util.PropertiesUtil;

/**
 * A Composite Configuration.
 */
public class CompositeConfiguration extends AbstractConfiguration implements Reconfigurable {

    /**
     * Allow the ConfigurationFactory class to be specified as a system property.
     */
    public static final String MERGE_STRATEGY_PROPERTY = "log4j.mergeStrategy";

    private static final String[] VERBOSE_CLASSES = new String[] {ResolverUtil.class.getName()};

    private final List<? extends AbstractConfiguration> configurations;

    private MergeStrategy mergeStrategy;

    /**
     * Construct the CompositeConfiguration.
     *
     * @param configurations The List of Configurations to merge.
     */
    public CompositeConfiguration(final List<? extends AbstractConfiguration> configurations) {
        super(configurations.get(0).getLoggerContext(), ConfigurationSource.COMPOSITE_SOURCE);
        rootNode = configurations.get(0).getRootNode();
        this.configurations = configurations;
        final String mergeStrategyClassName = PropertiesUtil.getProperties().getStringProperty(MERGE_STRATEGY_PROPERTY,
                DefaultMergeStrategy.class.getName());
        try {
            mergeStrategy = Loader.newInstanceOf(mergeStrategyClassName);
        } catch (ClassNotFoundException | IllegalAccessException | NoSuchMethodException | InvocationTargetException |
                InstantiationException ex) {
            mergeStrategy = new DefaultMergeStrategy();
        }
        for (final AbstractConfiguration config : configurations) {
            mergeStrategy.mergeRootProperties(rootNode, config);
        }
        final StatusConfiguration statusConfig = new StatusConfiguration().withVerboseClasses(VERBOSE_CLASSES)
                .withStatus(getDefaultStatus());
        for (final Map.Entry<String, String> entry : rootNode.getAttributes().entrySet()) {
            final String key = entry.getKey();
            final String value = getStrSubstitutor().replace(entry.getValue());
            if ("status".equalsIgnoreCase(key)) {
                statusConfig.withStatus(value.toUpperCase());
            } else if ("dest".equalsIgnoreCase(key)) {
                statusConfig.withDestination(value);
            } else if ("shutdownHook".equalsIgnoreCase(key)) {
                isShutdownHookEnabled = !"disable".equalsIgnoreCase(value);
            } else if ("shutdownTimeout".equalsIgnoreCase(key)) {
                shutdownTimeoutMillis = Long.parseLong(value);
            } else if ("verbose".equalsIgnoreCase(key)) {
                statusConfig.withVerbosity(value);
            } else if ("packages".equalsIgnoreCase(key)) {
                pluginPackages.addAll(Arrays.asList(value.split(Patterns.COMMA_SEPARATOR)));
            } else if ("name".equalsIgnoreCase(key)) {
                setName(value);
            }
        }
        statusConfig.initialize();
    }

    @Override
    public void setup() {
        final AbstractConfiguration targetConfiguration = configurations.get(0);
        staffChildConfiguration(targetConfiguration);
        final WatchManager watchManager = getWatchManager();
        final WatchManager targetWatchManager = targetConfiguration.getWatchManager();
        if (targetWatchManager.getIntervalSeconds() > 0) {
            watchManager.setIntervalSeconds(targetWatchManager.getIntervalSeconds());
            final Map<Source, Watcher> watchers = targetWatchManager.getConfigurationWatchers();
            for (final Map.Entry<Source, Watcher> entry : watchers.entrySet()) {
                watchManager.watch(entry.getKey(), entry.getValue().newWatcher(this, listeners,
                    entry.getValue().getLastModified()));
            }
        }
        for (final AbstractConfiguration sourceConfiguration : configurations.subList(1, configurations.size())) {
            staffChildConfiguration(sourceConfiguration);
            final Node sourceRoot = sourceConfiguration.getRootNode();
            mergeStrategy.mergConfigurations(rootNode, sourceRoot, getPluginManager());
            if (LOGGER.isEnabled(Level.ALL)) {
                final StringBuilder sb = new StringBuilder();
                printNodes("", rootNode, sb);
                System.out.println(sb.toString());
            }
            final int monitorInterval = sourceConfiguration.getWatchManager().getIntervalSeconds();
            if (monitorInterval > 0) {
                final int currentInterval = watchManager.getIntervalSeconds();
                if (currentInterval <= 0 || monitorInterval < currentInterval) {
                    watchManager.setIntervalSeconds(monitorInterval);
                }
                final WatchManager sourceWatchManager = sourceConfiguration.getWatchManager();
                final Map<Source, Watcher> watchers = sourceWatchManager.getConfigurationWatchers();
                for (final Map.Entry<Source, Watcher> entry : watchers.entrySet()) {
                    watchManager.watch(entry.getKey(), entry.getValue().newWatcher(this, listeners,
                        entry.getValue().getLastModified()));
                }
            }
        }
    }

    @Override
    public Configuration reconfigure() {
        LOGGER.debug("Reconfiguring composite configuration");
        final List<AbstractConfiguration> configs = new ArrayList<>();
        final ConfigurationFactory factory = ConfigurationFactory.getInstance();
        for (final AbstractConfiguration config : configurations) {
            final ConfigurationSource source = config.getConfigurationSource();
            final URI sourceURI = source.getURI();
            Configuration currentConfig = config;
            if (sourceURI == null) {
                LOGGER.warn("Unable to determine URI for configuration {}, changes to it will be ignored",
                        config.getName());
            } else {
                currentConfig = factory.getConfiguration(getLoggerContext(), config.getName(), sourceURI);
                if (currentConfig == null) {
                    LOGGER.warn("Unable to reload configuration {}, changes to it will be ignored", config.getName());
                }
            }
            configs.add((AbstractConfiguration) currentConfig);

        }

        return new CompositeConfiguration(configs);
    }

    private void staffChildConfiguration(final AbstractConfiguration childConfiguration) {
        childConfiguration.setPluginManager(pluginManager);
        childConfiguration.setScriptManager(scriptManager);
        childConfiguration.setup();
    }

    private void printNodes(final String indent, final Node node, final StringBuilder sb) {
        sb.append(indent).append(node.getName()).append(" type: ").append(node.getType()).append("\n");
        sb.append(indent).append(node.getAttributes().toString()).append("\n");
        for (final Node child : node.getChildren()) {
            printNodes(indent + "  ", child, sb);
        }
    }

    @Override
    public String toString() {
        return getClass().getName() + "@" + Integer.toHexString(hashCode()) + " [configurations=" + configurations
                + ", mergeStrategy=" + mergeStrategy + ", rootNode=" + rootNode + ", listeners=" + listeners
                + ", pluginPackages=" + pluginPackages + ", pluginManager=" + pluginManager + ", isShutdownHookEnabled="
                + isShutdownHookEnabled + ", shutdownTimeoutMillis=" + shutdownTimeoutMillis + ", scriptManager="
                + scriptManager + "]";
    }
}

⏎ org/apache/logging/log4j/core/config/composite/CompositeConfiguration.java

Or download all of them as a single archive file:

File name: log4j-core-2.14.1-sources.jar
File size: 1281358 bytes
Release date: 2021-03-06
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