Apache Commons Codec library provides implementations of common encoders and decoders such as Base64, Hex, Phonetic and URLs.

Apache Commons Codec Source Code files are provided in both binary packge (commons-codec-3.15-bin.zip) and source package (commons-codec-3.15-src.zip). You can download them at Apache Commons Codec Website.

Apache Commons Codec Source Code has no dependencies. You can compile it to generate your own version of Apache Commons Codec JAR file.

The source code of Apache Commons Codec 1.15 is provided below:

⏎ org/apache/commons/codec/CharEncoding.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.commons.codec;

/**
 * Character encoding names required of every implementation of the Java platform.
 *
 * From the Java documentation <a
 * href="http://download.oracle.com/javase/7/docs/api/java/nio/charset/Charset.html">Standard charsets</a>:
 * <p>
 * <cite>Every implementation of the Java platform is required to support the following character encodings. Consult the
 * release documentation for your implementation to see if any other encodings are supported. Consult the release
 * documentation for your implementation to see if any other encodings are supported.</cite>
 * </p>
 *
 * <ul>
 * <li>{@code US-ASCII}<p>
 * Seven-bit ASCII, a.k.a. ISO646-US, a.k.a. the Basic Latin block of the Unicode character set.</p></li>
 * <li>{@code ISO-8859-1}<p>
 * ISO Latin Alphabet No. 1, a.k.a. ISO-LATIN-1.</p></li>
 * <li>{@code UTF-8}<p>
 * Eight-bit Unicode Transformation Format.</p></li>
 * <li>{@code UTF-16BE}<p>
 * Sixteen-bit Unicode Transformation Format, big-endian byte order.</p></li>
 * <li>{@code UTF-16LE}<p>
 * Sixteen-bit Unicode Transformation Format, little-endian byte order.</p></li>
 * <li>{@code UTF-16}<p>
 * Sixteen-bit Unicode Transformation Format, byte order specified by a mandatory initial byte-order mark (either order
 * accepted on input, big-endian used on output.)</p></li>
 * </ul>
 *
 * This perhaps would best belong in the [lang] project. Even if a similar interface is defined in [lang], it is not
 * foreseen that [codec] would be made to depend on [lang].
 *
 * <p>
 * This class is immutable and thread-safe.
 * </p>
 *
 * @see <a href="http://download.oracle.com/javase/7/docs/api/java/nio/charset/Charset.html">Standard charsets</a>
 * @since 1.4
 */
public class CharEncoding {

    /**
     * CharEncodingISO Latin Alphabet No. 1, a.k.a. ISO-LATIN-1.
     * <p>
     * Every implementation of the Java platform is required to support this character encoding.
     * </p>
     *
     * @see <a href="http://download.oracle.com/javase/7/docs/api/java/nio/charset/Charset.html">Standard charsets</a>
     */
    public static final String ISO_8859_1 = "ISO-8859-1";

    /**
     * Seven-bit ASCII, also known as ISO646-US, also known as the Basic Latin block of the Unicode character set.
     * <p>
     * Every implementation of the Java platform is required to support this character encoding.
     * </p>
     *
     * @see <a href="http://download.oracle.com/javase/7/docs/api/java/nio/charset/Charset.html">Standard charsets</a>
     */
    public static final String US_ASCII = "US-ASCII";

    /**
     * Sixteen-bit Unicode Transformation Format, The byte order specified by a mandatory initial byte-order mark
     * (either order accepted on input, big-endian used on output)
     * <p>
     * Every implementation of the Java platform is required to support this character encoding.
     * </p>
     *
     * @see <a href="http://download.oracle.com/javase/7/docs/api/java/nio/charset/Charset.html">Standard charsets</a>
     */
    public static final String UTF_16 = "UTF-16";

    /**
     * Sixteen-bit Unicode Transformation Format, big-endian byte order.
     * <p>
     * Every implementation of the Java platform is required to support this character encoding.
     * </p>
     *
     * @see <a href="http://download.oracle.com/javase/7/docs/api/java/nio/charset/Charset.html">Standard charsets</a>
     */
    public static final String UTF_16BE = "UTF-16BE";

    /**
     * Sixteen-bit Unicode Transformation Format, little-endian byte order.
     * <p>
     * Every implementation of the Java platform is required to support this character encoding.
     * </p>
     *
     * @see <a href="http://download.oracle.com/javase/7/docs/api/java/nio/charset/Charset.html">Standard charsets</a>
     */
    public static final String UTF_16LE = "UTF-16LE";

    /**
     * Eight-bit Unicode Transformation Format.
     * <p>
     * Every implementation of the Java platform is required to support this character encoding.
     * </p>
     *
     * @see <a href="http://download.oracle.com/javase/7/docs/api/java/nio/charset/Charset.html">Standard charsets</a>
     */
    public static final String UTF_8 = "UTF-8";
}

⏎ org/apache/commons/codec/CharEncoding.java

Or download all of them as a single archive file:

File name: commons-codec-1.15-sources.jar
File size: 364441 bytes
Release date: 2020-09-01
Download 

⇒ Download and Install commons-codec-1.15-bin.zip

⇐ What Is commons-codec.jar

⇑ Downloading and Reviewing commons-codec.jar

⇑⇑ FAQ for Apache Commons Codec JAR Library