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 org.apache.logging.log4j.core.LogEvent;
import org.apache.logging.log4j.util.PerformanceSensitive;

 * Equals pattern converter.
public abstract class EqualsBaseReplacementConverter extends LogEventPatternConverter {
    private final List<PatternFormatter> formatters;
    private final List<PatternFormatter> substitutionFormatters;
    private final String substitution;
    private final String testString;

     * Construct the converter.
     * @param name          converter name
     * @param style         converter style
     * @param formatters   The PatternFormatters to generate the text to manipulate.
     * @param testString   The test string.
     * @param substitution The substitution string.
     * @param parser        The PatternParser.
    protected EqualsBaseReplacementConverter(final String name, final String style,
                                            final List<PatternFormatter> formatters, final String testString,
                                            final String substitution, final PatternParser parser) {
        super(name, style);
        this.testString = testString;
        this.substitution = substitution;
        this.formatters = formatters;

        // check if substitution needs to be parsed
        substitutionFormatters = substitution.contains("%") ? parser.parse(substitution) : null;

     * {@inheritDoc}
    public void format(final LogEvent event, final StringBuilder toAppendTo) {
        final int initialSize = toAppendTo.length();
        for (int i = 0; i < formatters.size(); i++) {
            final PatternFormatter formatter = formatters.get(i);
            formatter.format(event, toAppendTo);
        if (equals(testString, toAppendTo, initialSize, toAppendTo.length() - initialSize)) {
            parseSubstitution(event, toAppendTo);

     * Returns true if the specified String equals the specified section of the specified StringBuilder.
     * @param str the String to compare
     * @param buff the StringBuilder to compare a section of
     * @param from start index in the StringBuilder
     * @param len length of the section in the StringBuilder
     * @return true if equal, false otherwise
    protected abstract boolean equals(String str, StringBuilder buff, int from, int len);

     * Adds the parsed substitution text to the specified buffer.
     * @param event the current log event
     * @param substitutionBuffer the StringBuilder to append the parsed substitution text to
    void parseSubstitution(final LogEvent event, final StringBuilder substitutionBuffer) {
        if (substitutionFormatters != null) {
            for (int i = 0; i < substitutionFormatters.size(); i++) {
                final PatternFormatter formatter = substitutionFormatters.get(i);
                formatter.format(event, substitutionBuffer);
        } else {



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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