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/lookup/JavaLookup.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.lookup;

import java.util.Locale;

import org.apache.logging.log4j.core.LogEvent;
import org.apache.logging.log4j.core.config.plugins.Plugin;
import org.apache.logging.log4j.util.Strings;

/**
 * Looks up keys related to Java: Java version, JRE version, VM version, and so on.
 */
@Plugin(name = "java", category = StrLookup.CATEGORY)
public class JavaLookup extends AbstractLookup {

    private final SystemPropertiesLookup spLookup = new SystemPropertiesLookup();

    /**
     * Accessible through the Lookup key {@code hw}.
     * @return hardware processor information.
     */
    public String getHardware() {
        return "processors: " + Runtime.getRuntime().availableProcessors() + ", architecture: "
                + getSystemProperty("os.arch") + this.getSystemProperty("-", "sun.arch.data.model")
                + this.getSystemProperty(", instruction sets: ", "sun.cpu.isalist");
    }

    /**
     * Accessible through the Lookup key {@code locale}.
     * @return system locale and file encoding information.
     */
    public String getLocale() {
        return "default locale: " + Locale.getDefault() + ", platform encoding: " + getSystemProperty("file.encoding");
    }

    /**
     * Accessible through the Lookup key {@code os}.
     * @return operating system information.
     */
    public String getOperatingSystem() {
        return getSystemProperty("os.name") + " " + getSystemProperty("os.version")
                + getSystemProperty(" ", "sun.os.patch.level") + ", architecture: " + getSystemProperty("os.arch")
                + getSystemProperty("-", "sun.arch.data.model");
    }

    /**
     * Accessible through the Lookup key {@code runtime}.
     * @return Java Runtime Environment information.
     */
    public String getRuntime() {
        return getSystemProperty("java.runtime.name") + " (build " + getSystemProperty("java.runtime.version")
                + ") from " + getSystemProperty("java.vendor");
    }

    private String getSystemProperty(final String name) {
        return spLookup.lookup(name);
    }

    private String getSystemProperty(final String prefix, final String name) {
        final String value = getSystemProperty(name);
        if (Strings.isEmpty(value)) {
            return Strings.EMPTY;
        }
        return prefix + value;
    }

    /**
     * Accessible through the Lookup key {@code vm}.
     * @return Java Virtual Machine information.
     */
    public String getVirtualMachine() {
        return getSystemProperty("java.vm.name") + " (build " + getSystemProperty("java.vm.version") + ", "
                + getSystemProperty("java.vm.info") + ")";
    }

    /**
     * Looks up the value of the environment variable.
     *
     * @param event
     *        The current LogEvent (is ignored by this StrLookup).
     * @param key
     *        the key to be looked up, may be null
     * @return The value of the environment variable.
     */
    @Override
    public String lookup(final LogEvent event, final String key) {
        switch (key) {
        case "version":
            return "Java version " + getSystemProperty("java.version");
        case "runtime":
            return getRuntime();
        case "vm":
            return getVirtualMachine();
        case "os":
            return getOperatingSystem();
        case "hw":
            return getHardware();
        case "locale":
            return getLocale();
        default:
            throw new IllegalArgumentException(key);
        }
    }
}

⏎ org/apache/logging/log4j/core/lookup/JavaLookup.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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