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/AppenderRef.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;

import org.apache.logging.log4j.Level;
import org.apache.logging.log4j.Logger;
import org.apache.logging.log4j.core.Filter;
import org.apache.logging.log4j.core.config.plugins.Plugin;
import org.apache.logging.log4j.core.config.plugins.PluginAliases;
import org.apache.logging.log4j.core.config.plugins.PluginAttribute;
import org.apache.logging.log4j.core.config.plugins.PluginElement;
import org.apache.logging.log4j.core.config.plugins.PluginFactory;
import org.apache.logging.log4j.status.StatusLogger;

/**
 * An Appender reference.
 */
@Plugin(name = "AppenderRef", category = Node.CATEGORY, printObject = true)
@PluginAliases("appender-ref")
public final class AppenderRef {
    private static final Logger LOGGER = StatusLogger.getLogger();

    private final String ref;
    private final Level level;
    private final Filter filter;

    private AppenderRef(final String ref, final Level level, final Filter filter) {
        this.ref = ref;
        this.level = level;
        this.filter = filter;
    }

    public String getRef() {
        return ref;
    }

    public Level getLevel() {
        return level;
    }

    public Filter getFilter() {
        return filter;
    }

    @Override
    public String toString() {
        return ref;
    }

    /**
     * Create an Appender reference.
     * @param ref The name of the Appender.
     * @param level The Level to filter against.
     * @param filter The filter(s) to use.
     * @return The name of the Appender.
     */
    @PluginFactory
    public static AppenderRef createAppenderRef(
            @PluginAttribute("ref") final String ref,
            @PluginAttribute("level") final Level level,
            @PluginElement("Filter") final Filter filter) {

        if (ref == null) {
            LOGGER.error("Appender references must contain a reference");
            return null;
        }
        return new AppenderRef(ref, level, filter);
    }
}

⏎ org/apache/logging/log4j/core/config/AppenderRef.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
Download 

⇒ Source Code for Apache Log4j JDK Logging Adapter

⇐ Source Code for Apache Log4j API

⇑ Downloading and Reviewing Apache Log4j Packages

⇑⇑ FAQ for Apache Log4j