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 org.apache.logging.log4j.core.LogEvent;
import org.apache.logging.log4j.core.impl.LocationAware;

public class PatternFormatter {
    private final LogEventPatternConverter converter;
    private final FormattingInfo field;
    private final boolean skipFormattingInfo;

    public PatternFormatter(final LogEventPatternConverter converter, final FormattingInfo field) {
        this.converter = converter;
        this.field = field;
        this.skipFormattingInfo = field == FormattingInfo.getDefault();

    public void format(final LogEvent event, final StringBuilder buf) {
        if (skipFormattingInfo) {
            converter.format(event, buf);
        } else {
            formatWithInfo(event, buf);
    private void formatWithInfo(final LogEvent event, final StringBuilder buf) {
        final int startField = buf.length();
        converter.format(event, buf);
        field.format(startField, buf);

    public LogEventPatternConverter getConverter() {
        return converter;

    public FormattingInfo getFormattingInfo() {
        return field;

     * Normally pattern formatters are not meant to handle Exceptions although few pattern formatters might.
     * <p>
     * By examining the return values for this method, the containing layout will determine whether it handles
     * throwables or not.
     * </p>
     * @return true if this PatternConverter handles throwables
    public boolean handlesThrowable() {
        return converter.handlesThrowable();

     * Most pattern formatters do not use location information. When they do they should return true here
     * so that the logging system can efficiently capture it.
     * @return true if location information is required.
    public boolean requiresLocation() {
        return converter instanceof LocationAware && ((LocationAware) converter).requiresLocation();

     * Returns a String suitable for debugging.
     * @return a String suitable for debugging.
    public String toString() {
        final StringBuilder sb = new StringBuilder();
        sb.append(", field=");
        return sb.toString();



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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