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/appender/AppenderSet.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.appender;

import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.apache.logging.log4j.core.Appender;
import org.apache.logging.log4j.core.Core;
import org.apache.logging.log4j.core.config.Configuration;
import org.apache.logging.log4j.core.config.Node;
import org.apache.logging.log4j.core.config.plugins.Plugin;
import org.apache.logging.log4j.core.config.plugins.PluginBuilderFactory;
import org.apache.logging.log4j.core.config.plugins.PluginConfiguration;
import org.apache.logging.log4j.core.config.plugins.PluginNode;
import org.apache.logging.log4j.core.config.plugins.validation.constraints.Required;
import org.apache.logging.log4j.status.StatusLogger;

/**
 * A deferred plugin for appenders.
 */
@Plugin(name = "AppenderSet", category = Core.CATEGORY_NAME, printObject = true, deferChildren = true)
public class AppenderSet {

    public static class Builder implements org.apache.logging.log4j.core.util.Builder<AppenderSet> {

        @PluginNode
        private Node node;

        @PluginConfiguration
        @Required
        private Configuration configuration;

        @Override
        public AppenderSet build() {
            if (configuration == null) {
                LOGGER.error("Configuration is missing from AppenderSet {}", this);
                return null;
            }
            if (node == null) {
                LOGGER.error("No node in AppenderSet {}", this);
                return null;
            }
            final List<Node> children = node.getChildren();
            if (children == null) {
                LOGGER.error("No children node in AppenderSet {}", this);
                return null;
            }
            final Map<String, Node> map = new HashMap<>(children.size());
            for (final Node childNode : children) {
                final String key = childNode.getAttributes().get("name");
                if (key == null) {
                    LOGGER.error("The attribute 'name' is missing from from the node {} in AppenderSet {}",
                            childNode, children);
                } else {
                    map.put(key, childNode);
                }
            }
            return new AppenderSet(configuration, map);
        }

        public Node getNode() {
            return node;
        }

        public Configuration getConfiguration() {
            return configuration;
        }

        public Builder withNode(@SuppressWarnings("hiding") final Node node) {
            this.node = node;
            return this;
        }

        public Builder withConfiguration(@SuppressWarnings("hiding") final Configuration configuration) {
            this.configuration = configuration;
            return this;
        }

        @Override
        public String toString() {
            return getClass().getName() + " [node=" + node + ", configuration=" + configuration + "]";
        }

    }

    private static final StatusLogger LOGGER = StatusLogger.getLogger();

    private final Configuration configuration;
    private final Map<String, Node> nodeMap;

    @PluginBuilderFactory
    public static Builder newBuilder() {
        return new Builder();
    }

    private AppenderSet(final Configuration configuration, final Map<String, Node> appenders) {
        this.configuration = configuration;
        this.nodeMap = appenders;
    }

    public Appender createAppender(final String actualAppenderName, final String sourceAppenderName) {
        final Node node = nodeMap.get(actualAppenderName);
        if (node == null) {
            LOGGER.error("No node named {} in {}", actualAppenderName, this);
            return null;
        }
        node.getAttributes().put("name", sourceAppenderName);
        if (node.getType().getElementName().equals(Appender.ELEMENT_TYPE)) {
            final Node appNode = new Node(node);
            configuration.createConfiguration(appNode, null);
            if (appNode.getObject() instanceof Appender) {
                final Appender app = appNode.getObject();
                app.start();
                return app;
            }
            LOGGER.error("Unable to create Appender of type " + node.getName());
            return null;
        }
        LOGGER.error("No Appender was configured for name {} " + actualAppenderName);
        return null;
    }
}

⏎ org/apache/logging/log4j/core/appender/AppenderSet.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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