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.pattern;

import java.util.List;
import java.util.regex.Pattern;

import org.apache.logging.log4j.core.LogEvent;
import org.apache.logging.log4j.core.config.Configuration;
import org.apache.logging.log4j.core.config.plugins.Plugin;
import org.apache.logging.log4j.core.layout.PatternLayout;

 * Replacement pattern converter.
@Plugin(name = "replace", category = PatternConverter.CATEGORY)
@ConverterKeys({ "replace" })
public final class RegexReplacementConverter extends LogEventPatternConverter {

    private final Pattern pattern;

    private final String substitution;

    private final List<PatternFormatter> formatters;

     * Construct the converter.
     * @param formatters The PatternFormatters to generate the text to manipulate.
     * @param pattern The regular expression Pattern.
     * @param substitution The substitution string.
    private RegexReplacementConverter(final List<PatternFormatter> formatters,
                                      final Pattern pattern, final String substitution) {
        super("replace", "replace");
        this.pattern = pattern;
        this.substitution = substitution;
        this.formatters = formatters;

     * Gets an instance of the class.
     * @param config The current Configuration.
     * @param options pattern options, may be null.  If first element is "short",
     *                only the first line of the throwable will be formatted.
     * @return instance of class.
    public static RegexReplacementConverter newInstance(final Configuration config, final String[] options) {
        if (options.length != 3) {
            LOGGER.error("Incorrect number of options on replace. Expected 3 received " + options.length);
            return null;
        if (options[0] == null) {
            LOGGER.error("No pattern supplied on replace");
            return null;
        if (options[1] == null) {
            LOGGER.error("No regular expression supplied on replace");
            return null;
        if (options[2] == null) {
            LOGGER.error("No substitution supplied on replace");
            return null;
        final Pattern p = Pattern.compile(options[1]);
        final PatternParser parser = PatternLayout.createPatternParser(config);
        final List<PatternFormatter> formatters = parser.parse(options[0]);
        return new RegexReplacementConverter(formatters, p, options[2]);

     * {@inheritDoc}
    public void format(final LogEvent event, final StringBuilder toAppendTo) {
        final StringBuilder buf = new StringBuilder();
        for (final PatternFormatter formatter : formatters) {
            formatter.format(event, buf);



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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