Apache Commons Codec Source Code

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:

✍: FYIcenter

org/apache/commons/codec/binary/Hex.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.binary;

import java.nio.ByteBuffer;
import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;

import org.apache.commons.codec.BinaryDecoder;
import org.apache.commons.codec.BinaryEncoder;
import org.apache.commons.codec.CharEncoding;
import org.apache.commons.codec.DecoderException;
import org.apache.commons.codec.EncoderException;

/**
 * Converts hexadecimal Strings. The Charset used for certain operation can be set, the default is set in
 * {@link #DEFAULT_CHARSET_NAME}
 *
 * This class is thread-safe.
 *
 * @since 1.1
 */
public class Hex implements BinaryEncoder, BinaryDecoder {

    /**
     * Default charset is {@link StandardCharsets#UTF_8}.
     *
     * @since 1.7
     */
    public static final Charset DEFAULT_CHARSET = StandardCharsets.UTF_8;

    /**
     * Default charset name is {@link CharEncoding#UTF_8}.
     *
     * @since 1.4
     */
    public static final String DEFAULT_CHARSET_NAME = CharEncoding.UTF_8;

    /**
     * Used to build output as hex.
     */
    private static final char[] DIGITS_LOWER = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd',
            'e', 'f' };

    /**
     * Used to build output as hex.
     */
    private static final char[] DIGITS_UPPER = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D',
            'E', 'F' };

    /**
     * Converts an array of characters representing hexadecimal values into an array of bytes of those same values. The
     * returned array will be half the length of the passed array, as it takes two characters to represent any given
     * byte. An exception is thrown if the passed char array has an odd number of elements.
     *
     * @param data An array of characters containing hexadecimal digits
     * @return A byte array containing binary data decoded from the supplied char array.
     * @throws DecoderException Thrown if an odd number of characters or illegal characters are supplied
     */
    public static byte[] decodeHex(final char[] data) throws DecoderException {
        final byte[] out = new byte[data.length >> 1];
        decodeHex(data, out, 0);
        return out;
    }

    /**
     * Converts an array of characters representing hexadecimal values into an array of bytes of those same values. The
     * returned array will be half the length of the passed array, as it takes two characters to represent any given
     * byte. An exception is thrown if the passed char array has an odd number of elements.
     *
     * @param data An array of characters containing hexadecimal digits
     * @param out A byte array to contain the binary data decoded from the supplied char array.
     * @param outOffset The position within {@code out} to start writing the decoded bytes.
     * @return the number of bytes written to {@code out}.
     * @throws DecoderException Thrown if an odd number of characters or illegal characters are supplied
     * @since 1.15
     */
    public static int decodeHex(final char[] data, final byte[] out, final int outOffset) throws DecoderException {
        final int len = data.length;

        if ((len & 0x01) != 0) {
            throw new DecoderException("Odd number of characters.");
        }

        final int outLen = len >> 1;
        if (out.length - outOffset < outLen) {
            throw new DecoderException("Output array is not large enough to accommodate decoded data.");
        }

        // two characters form the hex value.
        for (int i = outOffset, j = 0; j < len; i++) {
            int f = toDigit(data[j], j) << 4;
            j++;
            f = f | toDigit(data[j], j);
            j++;
            out[i] = (byte) (f & 0xFF);
        }

        return outLen;
    }

    /**
     * Converts a String representing hexadecimal values into an array of bytes of those same values. The returned array
     * will be half the length of the passed String, as it takes two characters to represent any given byte. An
     * exception is thrown if the passed String has an odd number of elements.
     *
     * @param data A String containing hexadecimal digits
     * @return A byte array containing binary data decoded from the supplied char array.
     * @throws DecoderException Thrown if an odd number of characters or illegal characters are supplied
     * @since 1.11
     */ 
    public static byte[] decodeHex(final String data) throws DecoderException {
        return decodeHex(data.toCharArray());
    }

    /**
     * Converts an array of bytes into an array of characters representing the hexadecimal values of each byte in order.
     * The returned array will be double the length of the passed array, as it takes two characters to represent any
     * given byte.
     *
     * @param data a byte[] to convert to hex characters
     * @return A char[] containing lower-case hexadecimal characters
     */
    public static char[] encodeHex(final byte[] data) {
        return encodeHex(data, true);
    }

    /**
     * Converts an array of bytes into an array of characters representing the hexadecimal values of each byte in order.
     * The returned array will be double the length of the passed array, as it takes two characters to represent any
     * given byte.
     *
     * @param data        a byte[] to convert to Hex characters
     * @param toLowerCase {@code true} converts to lowercase, {@code false} to uppercase
     * @return A char[] containing hexadecimal characters in the selected case
     * @since 1.4
     */
    public static char[] encodeHex(final byte[] data, final boolean toLowerCase) {
        return encodeHex(data, toLowerCase ? DIGITS_LOWER : DIGITS_UPPER);
    }

    /**
     * Converts an array of bytes into an array of characters representing the hexadecimal values of each byte in order.
     * The returned array will be double the length of the passed array, as it takes two characters to represent any
     * given byte.
     *
     * @param data     a byte[] to convert to hex characters
     * @param toDigits the output alphabet (must contain at least 16 chars)
     * @return A char[] containing the appropriate characters from the alphabet For best results, this should be either
     *         upper- or lower-case hex.
     * @since 1.4
     */
    protected static char[] encodeHex(final byte[] data, final char[] toDigits) {
        final int l = data.length;
        final char[] out = new char[l << 1];
        encodeHex(data, 0, data.length, toDigits, out, 0);
        return out;
    }

    /**
     * Converts an array of bytes into an array of characters representing the hexadecimal values of each byte in order.
     *
     * @param data a byte[] to convert to hex characters
     * @param dataOffset the position in {@code data} to start encoding from
     * @param dataLen the number of bytes from {@code dataOffset} to encode
     * @param toLowerCase {@code true} converts to lowercase, {@code false} to uppercase
     * @return A char[] containing the appropriate characters from the alphabet For best results, this should be either
     *         upper- or lower-case hex.
     * @since 1.15
     */
    public static char[] encodeHex(final byte[] data, final int dataOffset, final int dataLen,
            final boolean toLowerCase) {
        final char[] out = new char[dataLen << 1];
        encodeHex(data, dataOffset, dataLen, toLowerCase ? DIGITS_LOWER : DIGITS_UPPER, out, 0);
        return out;
    }

    /**
     * Converts an array of bytes into an array of characters representing the hexadecimal values of each byte in order.
     *
     * @param data a byte[] to convert to hex characters
     * @param dataOffset the position in {@code data} to start encoding from
     * @param dataLen the number of bytes from {@code dataOffset} to encode
     * @param toLowerCase {@code true} converts to lowercase, {@code false} to uppercase
     * @param out a char[] which will hold the resultant appropriate characters from the alphabet.
     * @param outOffset the position within {@code out} at which to start writing the encoded characters.
     * @since 1.15
     */
    public static void encodeHex(final byte[] data, final int dataOffset, final int dataLen,
            final boolean toLowerCase, final char[] out, final int outOffset) {
        encodeHex(data, dataOffset, dataLen, toLowerCase ? DIGITS_LOWER : DIGITS_UPPER, out, outOffset);
    }

    /**
     * Converts an array of bytes into an array of characters representing the hexadecimal values of each byte in order.
     *
     * @param data a byte[] to convert to hex characters
     * @param dataOffset the position in {@code data} to start encoding from
     * @param dataLen the number of bytes from {@code dataOffset} to encode
     * @param toDigits the output alphabet (must contain at least 16 chars)
     * @param out a char[] which will hold the resultant appropriate characters from the alphabet.
     * @param outOffset the position within {@code out} at which to start writing the encoded characters.
     */
    private static void encodeHex(final byte[] data, final int dataOffset, final int dataLen, final char[] toDigits,
            final char[] out, final int outOffset) {
        // two characters form the hex value.
        for (int i = dataOffset, j = outOffset; i < dataOffset + dataLen; i++) {
            out[j++] = toDigits[(0xF0 & data[i]) >>> 4];
            out[j++] = toDigits[0x0F & data[i]];
        }
    }

    /**
     * Converts a byte buffer into an array of characters representing the hexadecimal values of each byte in order. The
     * returned array will be double the length of the passed array, as it takes two characters to represent any given
     * byte.
     *
     * <p>All bytes identified by {@link ByteBuffer#remaining()} will be used; after this method
     * the value {@link ByteBuffer#remaining() remaining()} will be zero.</p>
     *
     * @param data a byte buffer to convert to hex characters
     * @return A char[] containing lower-case hexadecimal characters
     * @since 1.11
     */
    public static char[] encodeHex(final ByteBuffer data) {
        return encodeHex(data, true);
    }

    /**
     * Converts a byte buffer into an array of characters representing the hexadecimal values of each byte in order. The
     * returned array will be double the length of the passed array, as it takes two characters to represent any given
     * byte.
     *
     * <p>All bytes identified by {@link ByteBuffer#remaining()} will be used; after this method
     * the value {@link ByteBuffer#remaining() remaining()} will be zero.</p>
     *
     * @param data        a byte buffer to convert to hex characters
     * @param toLowerCase {@code true} converts to lowercase, {@code false} to uppercase
     * @return A char[] containing hexadecimal characters in the selected case
     * @since 1.11
     */
    public static char[] encodeHex(final ByteBuffer data, final boolean toLowerCase) {
        return encodeHex(data, toLowerCase ? DIGITS_LOWER : DIGITS_UPPER);
    }

    /**
     * Converts a byte buffer into an array of characters representing the hexadecimal values of each byte in order. The
     * returned array will be double the length of the passed array, as it takes two characters to represent any given
     * byte.
     *
     * <p>All bytes identified by {@link ByteBuffer#remaining()} will be used; after this method
     * the value {@link ByteBuffer#remaining() remaining()} will be zero.</p>
     *
     * @param byteBuffer a byte buffer to convert to hex characters
     * @param toDigits   the output alphabet (must be at least 16 characters)
     * @return A char[] containing the appropriate characters from the alphabet For best results, this should be either
     *         upper- or lower-case hex.
     * @since 1.11
     */
    protected static char[] encodeHex(final ByteBuffer byteBuffer, final char[] toDigits) {
        return encodeHex(toByteArray(byteBuffer), toDigits);
    }

    /**
     * Converts an array of bytes into a String representing the hexadecimal values of each byte in order. The returned
     * String will be double the length of the passed array, as it takes two characters to represent any given byte.
     *
     * @param data a byte[] to convert to hex characters
     * @return A String containing lower-case hexadecimal characters
     * @since 1.4
     */
    public static String encodeHexString(final byte[] data) {
        return new String(encodeHex(data));
    }

    /**
     * Converts an array of bytes into a String representing the hexadecimal values of each byte in order. The returned
     * String will be double the length of the passed array, as it takes two characters to represent any given byte.
     *
     * @param data        a byte[] to convert to hex characters
     * @param toLowerCase {@code true} converts to lowercase, {@code false} to uppercase
     * @return A String containing lower-case hexadecimal characters
     * @since 1.11
     */
    public static String encodeHexString(final byte[] data, final boolean toLowerCase) {
        return new String(encodeHex(data, toLowerCase));
    }

    /**
     * Converts a byte buffer into a String representing the hexadecimal values of each byte in order. The returned
     * String will be double the length of the passed array, as it takes two characters to represent any given byte.
     *
     * <p>All bytes identified by {@link ByteBuffer#remaining()} will be used; after this method
     * the value {@link ByteBuffer#remaining() remaining()} will be zero.</p>
     *
     * @param data a byte buffer to convert to hex characters
     * @return A String containing lower-case hexadecimal characters
     * @since 1.11
     */
    public static String encodeHexString(final ByteBuffer data) {
        return new String(encodeHex(data));
    }

    /**
     * Converts a byte buffer into a String representing the hexadecimal values of each byte in order. The returned
     * String will be double the length of the passed array, as it takes two characters to represent any given byte.
     *
     * <p>All bytes identified by {@link ByteBuffer#remaining()} will be used; after this method
     * the value {@link ByteBuffer#remaining() remaining()} will be zero.</p>
     *
     * @param data        a byte buffer to convert to hex characters
     * @param toLowerCase {@code true} converts to lowercase, {@code false} to uppercase
     * @return A String containing lower-case hexadecimal characters
     * @since 1.11
     */
    public static String encodeHexString(final ByteBuffer data, final boolean toLowerCase) {
        return new String(encodeHex(data, toLowerCase));
    }

    /**
     * Convert the byte buffer to a byte array. All bytes identified by
     * {@link ByteBuffer#remaining()} will be used.
     *
     * @param byteBuffer the byte buffer
     * @return the byte[]
     */
    private static byte[] toByteArray(final ByteBuffer byteBuffer) {
        final int remaining = byteBuffer.remaining();
        // Use the underlying buffer if possible
        if (byteBuffer.hasArray()) {
            final byte[] byteArray = byteBuffer.array();
            if (remaining == byteArray.length) {
                byteBuffer.position(remaining);
                return byteArray;
            }
        }
        // Copy the bytes
        final byte[] byteArray = new byte[remaining];
        byteBuffer.get(byteArray);
        return byteArray;
    }

    /**
     * Converts a hexadecimal character to an integer.
     *
     * @param ch    A character to convert to an integer digit
     * @param index The index of the character in the source
     * @return An integer
     * @throws DecoderException Thrown if ch is an illegal hex character
     */
    protected static int toDigit(final char ch, final int index) throws DecoderException {
        final int digit = Character.digit(ch, 16);
        if (digit == -1) {
            throw new DecoderException("Illegal hexadecimal character " + ch + " at index " + index);
        }
        return digit;
    }

    private final Charset charset;

    /**
     * Creates a new codec with the default charset name {@link #DEFAULT_CHARSET}
     */
    public Hex() {
        // use default encoding
        this.charset = DEFAULT_CHARSET;
    }

    /**
     * Creates a new codec with the given Charset.
     *
     * @param charset the charset.
     * @since 1.7
     */
    public Hex(final Charset charset) {
        this.charset = charset;
    }

    /**
     * Creates a new codec with the given charset name.
     *
     * @param charsetName the charset name.
     * @throws java.nio.charset.UnsupportedCharsetException If the named charset is unavailable
     * @since 1.4
     * @since 1.7 throws UnsupportedCharsetException if the named charset is unavailable
     */
    public Hex(final String charsetName) {
        this(Charset.forName(charsetName));
    }

    /**
     * Converts an array of character bytes representing hexadecimal values into an array of bytes of those same values.
     * The returned array will be half the length of the passed array, as it takes two characters to represent any given
     * byte. An exception is thrown if the passed char array has an odd number of elements.
     *
     * @param array An array of character bytes containing hexadecimal digits
     * @return A byte array containing binary data decoded from the supplied byte array (representing characters).
     * @throws DecoderException Thrown if an odd number of characters is supplied to this function
     * @see #decodeHex(char[])
     */
    @Override
    public byte[] decode(final byte[] array) throws DecoderException {
        return decodeHex(new String(array, getCharset()).toCharArray());
    }

    /**
     * Converts a buffer of character bytes representing hexadecimal values into an array of bytes of those same values.
     * The returned array will be half the length of the passed array, as it takes two characters to represent any given
     * byte. An exception is thrown if the passed char array has an odd number of elements.
     *
     * <p>All bytes identified by {@link ByteBuffer#remaining()} will be used; after this method
     * the value {@link ByteBuffer#remaining() remaining()} will be zero.</p>
     *
     * @param buffer An array of character bytes containing hexadecimal digits
     * @return A byte array containing binary data decoded from the supplied byte array (representing characters).
     * @throws DecoderException Thrown if an odd number of characters is supplied to this function
     * @see #decodeHex(char[])
     * @since 1.11
     */
    public byte[] decode(final ByteBuffer buffer) throws DecoderException {
        return decodeHex(new String(toByteArray(buffer), getCharset()).toCharArray());
    }

    /**
     * Converts a String or an array of character bytes representing hexadecimal values into an array of bytes of those
     * same values. The returned array will be half the length of the passed String or array, as it takes two characters
     * to represent any given byte. An exception is thrown if the passed char array has an odd number of elements.
     *
     * @param object A String, ByteBuffer, byte[], or an array of character bytes containing hexadecimal digits
     * @return A byte array containing binary data decoded from the supplied byte array (representing characters).
     * @throws DecoderException Thrown if an odd number of characters is supplied to this function or the object is not
     *                          a String or char[]
     * @see #decodeHex(char[])
     */
    @Override
    public Object decode(final Object object) throws DecoderException {
        if (object instanceof String) {
            return decode(((String) object).toCharArray());
        } else if (object instanceof byte[]) {
            return decode((byte[]) object);
        } else if (object instanceof ByteBuffer) {
            return decode((ByteBuffer) object);
        } else {
            try {
                return decodeHex((char[]) object);
            } catch (final ClassCastException e) {
                throw new DecoderException(e.getMessage(), e);
            }
        }
    }

    /**
     * Converts an array of bytes into an array of bytes for the characters representing the hexadecimal values of each
     * byte in order. The returned array will be double the length of the passed array, as it takes two characters to
     * represent any given byte.
     * <p>
     * The conversion from hexadecimal characters to the returned bytes is performed with the charset named by
     * {@link #getCharset()}.
     * </p>
     *
     * @param array a byte[] to convert to hex characters
     * @return A byte[] containing the bytes of the lower-case hexadecimal characters
     * @since 1.7 No longer throws IllegalStateException if the charsetName is invalid.
     * @see #encodeHex(byte[])
     */
    @Override
    public byte[] encode(final byte[] array) {
        return encodeHexString(array).getBytes(this.getCharset());
    }

    /**
     * Converts byte buffer into an array of bytes for the characters representing the hexadecimal values of each byte
     * in order. The returned array will be double the length of the passed array, as it takes two characters to
     * represent any given byte.
     *
     * <p>The conversion from hexadecimal characters to the returned bytes is performed with the charset named by
     * {@link #getCharset()}.</p>
     *
     * <p>All bytes identified by {@link ByteBuffer#remaining()} will be used; after this method
     * the value {@link ByteBuffer#remaining() remaining()} will be zero.</p>
     *
     * @param array a byte buffer to convert to hex characters
     * @return A byte[] containing the bytes of the lower-case hexadecimal characters
     * @see #encodeHex(byte[])
     * @since 1.11
     */
    public byte[] encode(final ByteBuffer array) {
        return encodeHexString(array).getBytes(this.getCharset());
    }

    /**
     * Converts a String or an array of bytes into an array of characters representing the hexadecimal values of each
     * byte in order. The returned array will be double the length of the passed String or array, as it takes two
     * characters to represent any given byte.
     * <p>
     * The conversion from hexadecimal characters to bytes to be encoded to performed with the charset named by
     * {@link #getCharset()}.
     * </p>
     *
     * @param object a String, ByteBuffer, or byte[] to convert to hex characters
     * @return A char[] containing lower-case hexadecimal characters
     * @throws EncoderException Thrown if the given object is not a String or byte[]
     * @see #encodeHex(byte[])
     */
    @Override
    public Object encode(final Object object) throws EncoderException {
        byte[] byteArray;
        if (object instanceof String) {
            byteArray = ((String) object).getBytes(this.getCharset());
        } else if (object instanceof ByteBuffer) {
            byteArray = toByteArray((ByteBuffer) object);
        } else {
            try {
                byteArray = (byte[]) object;
            } catch (final ClassCastException e) {
                throw new EncoderException(e.getMessage(), e);
            }
        }
        return encodeHex(byteArray);
    }

    /**
     * Gets the charset.
     *
     * @return the charset.
     * @since 1.7
     */
    public Charset getCharset() {
        return this.charset;
    }

    /**
     * Gets the charset name.
     *
     * @return the charset name.
     * @since 1.4
     */
    public String getCharsetName() {
        return this.charset.name();
    }

    /**
     * Returns a string representation of the object, which includes the charset name.
     *
     * @return a string representation of the object.
     */
    @Override
    public String toString() {
        return super.toString() + "[charsetName=" + this.charset + "]";
    }
}

org/apache/commons/codec/binary/Hex.java

 

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