Source Code for Apache Log4j API

Apache Log4j API provides the interface that applications should code to and provides the adapter components required for implementers to create a logging implementation. Apache Log4j API is a required module to use Apache Log4j.

Bytecode (Java 8) for Apache Log4j API is provided in a separate JAR file like log4j-api-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 API 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.simple;


import org.apache.logging.log4j.Level;
import org.apache.logging.log4j.message.MessageFactory;
import org.apache.logging.log4j.spi.AbstractLogger;
import org.apache.logging.log4j.spi.ExtendedLogger;
import org.apache.logging.log4j.spi.LoggerContext;
import org.apache.logging.log4j.spi.LoggerRegistry;
import org.apache.logging.log4j.util.PropertiesUtil;

public class SimpleLoggerContext implements LoggerContext {

    private static final String SYSTEM_OUT = "system.out";

    private static final String SYSTEM_ERR = "system.err";

    /** The default format to use when formatting dates */
    protected static final String DEFAULT_DATE_TIME_FORMAT = "yyyy/MM/dd HH:mm:ss:SSS zzz";

    /** All system properties used by <code>SimpleLog</code> start with this */
    protected static final String SYSTEM_PREFIX = "org.apache.logging.log4j.simplelog.";

    private final PropertiesUtil props;

    /** Include the instance name in the log message? */
    private final boolean showLogName;

     * Include the short name (last component) of the logger in the log message. Defaults to true - otherwise we'll be
     * lost in a flood of messages without knowing who sends them.
    private final boolean showShortName;
    /** Include the current time in the log message */
    private final boolean showDateTime;
    /** Include the ThreadContextMap in the log message */
    private final boolean showContextMap;
    /** The date and time format to use in the log message */
    private final String dateTimeFormat;

    private final Level defaultLevel;

    private final PrintStream stream;

    private final LoggerRegistry<ExtendedLogger> loggerRegistry = new LoggerRegistry<>();

    public SimpleLoggerContext() {
        props = new PropertiesUtil("");

        showContextMap = props.getBooleanProperty(SYSTEM_PREFIX + "showContextMap", false);
        showLogName = props.getBooleanProperty(SYSTEM_PREFIX + "showlogname", false);
        showShortName = props.getBooleanProperty(SYSTEM_PREFIX + "showShortLogname", true);
        showDateTime = props.getBooleanProperty(SYSTEM_PREFIX + "showdatetime", false);
        final String lvl = props.getStringProperty(SYSTEM_PREFIX + "level");
        defaultLevel = Level.toLevel(lvl, Level.ERROR);

        dateTimeFormat = showDateTime ? props.getStringProperty(SimpleLoggerContext.SYSTEM_PREFIX + "dateTimeFormat",
                DEFAULT_DATE_TIME_FORMAT) : null;

        final String fileName = props.getStringProperty(SYSTEM_PREFIX + "logFile", SYSTEM_ERR);
        PrintStream ps;
        if (SYSTEM_ERR.equalsIgnoreCase(fileName)) {
            ps = System.err;
        } else if (SYSTEM_OUT.equalsIgnoreCase(fileName)) {
            ps = System.out;
        } else {
            try {
                final FileOutputStream os = new FileOutputStream(fileName);
                ps = new PrintStream(os);
            } catch (final FileNotFoundException fnfe) {
                ps = System.err;
        } = ps;

    public ExtendedLogger getLogger(final String name) {
        return getLogger(name, null);

    public ExtendedLogger getLogger(final String name, final MessageFactory messageFactory) {
        // Note: This is the only method where we add entries to the 'loggerRegistry' ivar.
        final ExtendedLogger extendedLogger = loggerRegistry.getLogger(name, messageFactory);
        if (extendedLogger != null) {
            AbstractLogger.checkMessageFactory(extendedLogger, messageFactory);
            return extendedLogger;
        final SimpleLogger simpleLogger = new SimpleLogger(name, defaultLevel, showLogName, showShortName, showDateTime,
                showContextMap, dateTimeFormat, messageFactory, props, stream);
        loggerRegistry.putIfAbsent(name, messageFactory, simpleLogger);
        return loggerRegistry.getLogger(name, messageFactory);

    public boolean hasLogger(final String name) {
        return false;

    public boolean hasLogger(final String name, final MessageFactory messageFactory) {
        return false;

    public boolean hasLogger(final String name, final Class<? extends MessageFactory> messageFactoryClass) {
        return false;

    public Object getExternalContext() {
        return null;




Or download all of them as a single archive file:

File name: log4j-api-2.14.1-sources.jar
File size: 264773 bytes
Release date: 2021-03-06


Source Code for Apache Log4j Core Implementation

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