Source Code for Apache Log4j Core Implementation

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 and source package like You can download them at Apache Log4j Website.

You can also browse Source Code files for Apache Log4j Core Implementation 2.14.1 below.



 * 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
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * See the license for the specific language governing permissions and
 * limitations under the license.
package org.apache.logging.log4j.core.config;

import java.util.Objects;

import org.apache.logging.log4j.Logger;
import org.apache.logging.log4j.core.config.plugins.Plugin;
import org.apache.logging.log4j.core.config.plugins.PluginAttribute;
import org.apache.logging.log4j.core.config.plugins.PluginFactory;
import org.apache.logging.log4j.core.config.plugins.PluginValue;
import org.apache.logging.log4j.status.StatusLogger;
import org.apache.logging.log4j.util.Strings;

 * Represents a key/value pair in the configuration.
@Plugin(name = "property", category = Node.CATEGORY, printObject = true)
public final class Property {

     * @since 2.11.2
    public static final Property[] EMPTY_ARRAY = new Property[0];

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

    private final String name;
    private final String value;
    private final boolean valueNeedsLookup;

    private Property(final String name, final String value) { = name;
        this.value = value;
        this.valueNeedsLookup = value != null && value.contains("${");

     * Returns the property name.
     * @return the property name.
    public String getName() {
        return name;

     * Returns the property value.
     * @return the value of the property.
    public String getValue() {
        return Objects.toString(value, Strings.EMPTY); // LOG4J2-1313 null would be same as Property not existing

     * Returns {@code true} if the value contains a substitutable property that requires a lookup to be resolved.
     * @return {@code true} if the value contains {@code "${"}, {@code false} otherwise
    public boolean isValueNeedsLookup() {
        return valueNeedsLookup;

     * Creates a Property.
     * @param name The key.
     * @param value The value.
     * @return A Property.
    public static Property createProperty(
            @PluginAttribute("name") final String name,
            @PluginValue("value") final String value) {
        if (name == null) {
            LOGGER.error("Property name cannot be null");
        return new Property(name, value);

    public String toString() {
        return name + '=' + getValue();



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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