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.appender.rolling;

import java.text.NumberFormat;
import java.text.ParseException;
import java.util.Locale;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import org.apache.logging.log4j.Logger;
import org.apache.logging.log4j.status.StatusLogger;

 * FileSize utility class.
public final class FileSize {
    private static final Logger LOGGER = StatusLogger.getLogger();

    private static final long KB = 1024;
    private static final long MB = KB * KB;
    private static final long GB = KB * MB;

     * Pattern for string parsing.
    private static final Pattern VALUE_PATTERN =
        Pattern.compile("([0-9]+([\\.,][0-9]+)?)\\s*(|K|M|G)B?", Pattern.CASE_INSENSITIVE);

    private FileSize() {

     * Converts a string to a number of bytes. Strings consist of a floating point value followed by
     * K, M, or G for kilobytes, megabytes, gigabytes, respectively. The
     * abbreviations KB, MB, and GB are also accepted. Matching is case insensitive.
     * @param string The string to convert
     * @param defaultValue The default value if a problem is detected parsing.
     * @return The Bytes value for the string
    public static long parse(final String string, final long defaultValue) {
        final Matcher matcher = VALUE_PATTERN.matcher(string);

        // Valid input?
        if (matcher.matches()) {
            try {
                // Get double precision value
                final long value = NumberFormat.getNumberInstance(Locale.ROOT).parse(

                // Get units specified
                final String units =;

                if (units.isEmpty()) {
                    return value;
                } else if (units.equalsIgnoreCase("K")) {
                    return value * KB;
                } else if (units.equalsIgnoreCase("M")) {
                    return value * MB;
                } else if (units.equalsIgnoreCase("G")) {
                    return value * GB;
                } else {
                    LOGGER.error("FileSize units not recognized: " + string);
                    return defaultValue;
            } catch (final ParseException e) {
                LOGGER.error("FileSize unable to parse numeric part: " + string, e);
                return defaultValue;
        LOGGER.error("FileSize unable to parse bytes: " + string);
        return defaultValue;




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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