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/JsonUtils.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;

/**
 * This class is borrowed from <a href="https://github.com/FasterXML/jackson-core">Jackson</a>.
 */
public final class JsonUtils {

    private static final char[] HC = "0123456789ABCDEF".toCharArray();

    /**
     * Read-only encoding table for first 128 Unicode code points (single-byte UTF-8 characters).
     * Value of 0 means "no escaping"; other positive values that value is character
     * to use after backslash; and negative values that generic (backslash - u)
     * escaping is to be used.
     */
    private static final int[] ESC_CODES;
    static {
        final int[] table = new int[128];
        // Control chars need generic escape sequence
        for (int i = 0; i < 32; ++i) {
            // 04-Mar-2011, tatu: Used to use "-(i + 1)", replaced with constant
            table[i] = -1;
        }
        /* Others (and some within that range too) have explicit shorter
         * sequences
         */
        table['"'] = '"';
        table['\\'] = '\\';
        // Escaping of slash is optional, so let's not add it
        table[0x08] = 'b';
        table[0x09] = 't';
        table[0x0C] = 'f';
        table[0x0A] = 'n';
        table[0x0D] = 'r';
        ESC_CODES = table;
    }

    /**
     * Temporary buffer used for composing quote/escape sequences
     */
    private final static ThreadLocal<char[]> _qbufLocal = new ThreadLocal<>();

    private static char[] getQBuf() {
        char[] _qbuf = _qbufLocal.get();
        if (_qbuf == null) {
            _qbuf = new char[6];
            _qbuf[0] = '\\';
            _qbuf[2] = '0';
            _qbuf[3] = '0';

            _qbufLocal.set(_qbuf);
        }
        return _qbuf;
    }

    /**
     * Quote text contents using JSON standard quoting, and append results to a supplied {@link StringBuilder}.
     */
    public static void quoteAsString(final CharSequence input, final StringBuilder output) {
        final char[] qbuf = getQBuf();
        final int escCodeCount = ESC_CODES.length;
        int inPtr = 0;
        final int inputLen = input.length();

        outer:
        while (inPtr < inputLen) {
            tight_loop:
            while (true) {
                final char c = input.charAt(inPtr);
                if (c < escCodeCount && ESC_CODES[c] != 0) {
                    break tight_loop;
                }
                output.append(c);
                if (++inPtr >= inputLen) {
                    break outer;
                }
            }
            // something to escape; 2 or 6-char variant?
            final char d = input.charAt(inPtr++);
            final int escCode = ESC_CODES[d];
            final int length = (escCode < 0)
                    ? _appendNumeric(d, qbuf)
                    : _appendNamed(escCode, qbuf);

            output.append(qbuf, 0, length);
        }
    }

    private static int _appendNumeric(final int value, final char[] qbuf) {
        qbuf[1] = 'u';
        // We know it's a control char, so only the last 2 chars are non-0
        qbuf[4] = HC[value >> 4];
        qbuf[5] = HC[value & 0xF];
        return 6;
    }

    private static int _appendNamed(final int esc, final char[] qbuf) {
        qbuf[1] = (char) esc;
        return 2;
    }

}

⏎ org/apache/logging/log4j/core/util/JsonUtils.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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