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 apache-log4j-2.14.1-bin.zip and source package like apache-log4j-2.14.1-src.zip. You can download them at Apache Log4j Website.

You can also browse Source Code files for Apache Log4j Core Implementation 2.14.1 below.

⏎ org/apache/logging/log4j/core/util/Constants.java

/*
 * 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
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the license for the specific language governing permissions and
 * limitations under the license.
 */
package org.apache.logging.log4j.core.util;

import org.apache.logging.log4j.util.PropertiesUtil;

/**
 * Log4j Constants.
 */
public final class Constants {

    /**
     * Name of the system property to use to identify the LogEvent factory.
     */
    public static final String LOG4J_LOG_EVENT_FACTORY = "Log4jLogEventFactory";

    /**
     * Name of the system property to use to identify the ContextSelector Class.
     */
    public static final String LOG4J_CONTEXT_SELECTOR = "Log4jContextSelector";

    /**
     * Property name for the default status (internal log4j logging) level to use if not specified in configuration.
     */
    public static final String LOG4J_DEFAULT_STATUS_LEVEL = "Log4jDefaultStatusLevel";

    /**
     * JNDI context name string literal.
     */
    public static final String JNDI_CONTEXT_NAME = "java:comp/env/log4j/context-name";

    /**
     * Number of milliseconds in a second.
     */
    public static final int MILLIS_IN_SECONDS = 1000;

    /**
     * Supports user request LOG4J2-898 to have the option to format a message in the background thread.
     */
    public static final boolean FORMAT_MESSAGES_IN_BACKGROUND = PropertiesUtil.getProperties().getBooleanProperty(
            "log4j.format.msg.async", false);

    /**
     * LOG4J2-2109 if {@code true}, MessagePatternConverter will always operate as though
     * <pre>%m{nolookups}</pre> is configured.
     *
     * @since 2.10
     */
    public static final boolean FORMAT_MESSAGES_PATTERN_DISABLE_LOOKUPS = PropertiesUtil.getProperties().getBooleanProperty(
            "log4j2.formatMsgNoLookups", false);

    /**
     * {@code true} if we think we are running in a web container, based on the boolean value of system property
     * "log4j2.is.webapp", or (if this system property is not set) whether the  {@code javax.servlet.Servlet} class
     * is present in the classpath.
     */
    public static final boolean IS_WEB_APP = org.apache.logging.log4j.util.Constants.IS_WEB_APP;

    /**
     * Kill switch for object pooling in ThreadLocals that enables much of the LOG4J2-1270 no-GC behaviour.
     * <p>
     * {@code True} for non-{@link #IS_WEB_APP web apps}, disable by setting system property
     * "log4j2.enable.threadlocals" to "false".
     *
     * @since 2.6
     */
    public static final boolean ENABLE_THREADLOCALS = org.apache.logging.log4j.util.Constants.ENABLE_THREADLOCALS;

    /**
     * Kill switch for garbage-free Layout behaviour that encodes LogEvents directly into
     * {@link org.apache.logging.log4j.core.layout.ByteBufferDestination}s without creating intermediate temporary
     * Objects.
     * <p>
     * {@code True} by default iff all loggers are asynchronous because system property
     * {@code Log4jContextSelector} is set to {@code org.apache.logging.log4j.core.async.AsyncLoggerContextSelector}.
     * Disable by setting system property "log4j2.enable.direct.encoders" to "false".
     *
     * @since 2.6
     */
    public static final boolean ENABLE_DIRECT_ENCODERS = PropertiesUtil.getProperties().getBooleanProperty(
            "log4j2.enable.direct.encoders", true); // enable GC-free text encoding by default
            // the alternative is to enable GC-free encoding only by default only when using all-async loggers:
            //AsyncLoggerContextSelector.class.getName().equals(PropertiesUtil.getProperties().getStringProperty(LOG4J_CONTEXT_SELECTOR)));

    /**
     * Initial StringBuilder size used in RingBuffer LogEvents to store the contents of reusable Messages.
     * <p>
     * The default value is {@value}, users can override with system property "log4j.initialReusableMsgSize".
     * </p>
     * @since 2.6
     */
    public static final int INITIAL_REUSABLE_MESSAGE_SIZE = size("log4j.initialReusableMsgSize", 128);

    /**
     * Maximum size of the StringBuilders used in RingBuffer LogEvents to store the contents of reusable Messages.
     * After a large message has been delivered to the appenders, the StringBuilder is trimmed to this size.
     * <p>
     * The default value is {@value}, which allows the StringBuilder to resize three times from its initial size.
     * Users can override with system property "log4j.maxReusableMsgSize".
     * </p>
     * @since 2.6
     */
    public static final int MAX_REUSABLE_MESSAGE_SIZE = size("log4j.maxReusableMsgSize", (128 * 2 + 2) * 2 + 2);

    /**
     * Size of CharBuffers used by text encoders.
     * <p>
     * The default value is {@value}, users can override with system property "log4j.encoder.charBufferSize".
     * </p>
     * @since 2.6
     */
    public static final int ENCODER_CHAR_BUFFER_SIZE = size("log4j.encoder.charBufferSize", 2048);

    /**
     * Default size of ByteBuffers used to encode LogEvents without allocating temporary objects.
     * <p>
     * The default value is {@value}, users can override with system property "log4j.encoder.byteBufferSize".
     * </p>
     * @see org.apache.logging.log4j.core.layout.ByteBufferDestination
     * @since 2.6
     */
    public static final int ENCODER_BYTE_BUFFER_SIZE = size("log4j.encoder.byteBufferSize", 8 * 1024);


    private static int size(final String property, final int defaultValue) {
        return PropertiesUtil.getProperties().getIntegerProperty(property, defaultValue);
    }

    /**
     * Prevent class instantiation.
     */
    private Constants() {
    }
}

⏎ org/apache/logging/log4j/core/util/Constants.java

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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