    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one or more
    003 * contributor license agreements.  See the NOTICE file distributed with
    004 * this work for additional information regarding copyright ownership.
    005 * The ASF licenses this file to You under the Apache License, Version 2.0
    006 * (the "License"); you may not use this file except in compliance with
    007 * the License.  You may obtain a copy of the License at
    008 *
    009 *      http://www.apache.org/licenses/LICENSE-2.0
    010 *
    011 * Unless required by applicable law or agreed to in writing, software
    012 * distributed under the License is distributed on an "AS IS" BASIS,
    013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014 * See the License for the specific language governing permissions and
    015 * limitations under the License.
    016 */
    017
    018package org.apache.commons.codec.binary;
    019
    020import java.nio.charset.Charset;
    021
    022import org.apache.commons.codec.BinaryDecoder;
    023import org.apache.commons.codec.BinaryEncoder;
    024import org.apache.commons.codec.CharEncoding;
    025import org.apache.commons.codec.Charsets;
    026import org.apache.commons.codec.DecoderException;
    027import org.apache.commons.codec.EncoderException;
    028
    029/**
    030 * Converts hexadecimal Strings. The charset used for certain operation can be set, the default is set in
    031 * {@link #DEFAULT_CHARSET_NAME}
    032 *
    033 * This class is thread-safe.
    034 *
    035 * @since 1.1
    036 * @version $Id: Hex.java 1619948 2014-08-22 22:53:55Z ggregory $
    037 */
    038public class Hex implements BinaryEncoder, BinaryDecoder {
    039
    040    /**
    041     * Default charset name is {@link Charsets#UTF_8}
    042     *
    043     * @since 1.7
    044     */
    045    public static final Charset DEFAULT_CHARSET = Charsets.UTF_8;
    046
    047    /**
    048     * Default charset name is {@link CharEncoding#UTF_8}
    049     *
    050     * @since 1.4
    051     */
    052    public static final String DEFAULT_CHARSET_NAME = CharEncoding.UTF_8;
    053
    054    /**
    055     * Used to build output as Hex
    056     */
    057    private static final char[] DIGITS_LOWER =
    058        {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'};
    059
    060    /**
    061     * Used to build output as Hex
    062     */
    063    private static final char[] DIGITS_UPPER =
    064        {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F'};
    065
    066    /**
    067     * Converts an array of characters representing hexadecimal values into an array of bytes of those same values. The
    068     * returned array will be half the length of the passed array, as it takes two characters to represent any given
    069     * byte. An exception is thrown if the passed char array has an odd number of elements.
    070     *
    071     * @param data
    072     *            An array of characters containing hexadecimal digits
    073     * @return A byte array containing binary data decoded from the supplied char array.
    074     * @throws DecoderException
    075     *             Thrown if an odd number or illegal of characters is supplied
    076     */
    077    public static byte[] decodeHex(final char[] data) throws DecoderException {
    078
    079        final int len = data.length;
    080
    081        if ((len & 0x01) != 0) {
    082            throw new DecoderException("Odd number of characters.");
    083        }
    084
    085        final byte[] out = new byte[len >> 1];
    086
    087        // two characters form the hex value.
    088        for (int i = 0, j = 0; j < len; i++) {
    089            int f = toDigit(data[j], j) << 4;
    090            j++;
    091            f = f | toDigit(data[j], j);
    092            j++;
    093            out[i] = (byte) (f & 0xFF);
    094        }
    095
    096        return out;
    097    }
    098
    099    /**
    100     * Converts an array of bytes into an array of characters representing the hexadecimal values of each byte in order.
    101     * The returned array will be double the length of the passed array, as it takes two characters to represent any
    102     * given byte.
    103     *
    104     * @param data
    105     *            a byte[] to convert to Hex characters
    106     * @return A char[] containing hexadecimal characters
    107     */
    108    public static char[] encodeHex(final byte[] data) {
    109        return encodeHex(data, true);
    110    }
    111
    112    /**
    113     * Converts an array of bytes into an array of characters representing the hexadecimal values of each byte in order.
    114     * The returned array will be double the length of the passed array, as it takes two characters to represent any
    115     * given byte.
    116     *
    117     * @param data
    118     *            a byte[] to convert to Hex characters
    119     * @param toLowerCase
    120     *            <code>true</code> converts to lowercase, <code>false</code> to uppercase
    121     * @return A char[] containing hexadecimal characters
    122     * @since 1.4
    123     */
    124    public static char[] encodeHex(final byte[] data, final boolean toLowerCase) {
    125        return encodeHex(data, toLowerCase ? DIGITS_LOWER : DIGITS_UPPER);
    126    }
    127
    128    /**
    129     * Converts an array of bytes into an array of characters representing the hexadecimal values of each byte in order.
    130     * The returned array will be double the length of the passed array, as it takes two characters to represent any
    131     * given byte.
    132     *
    133     * @param data
    134     *            a byte[] to convert to Hex characters
    135     * @param toDigits
    136     *            the output alphabet
    137     * @return A char[] containing hexadecimal characters
    138     * @since 1.4
    139     */
    140    protected static char[] encodeHex(final byte[] data, final char[] toDigits) {
    141        final int l = data.length;
    142        final char[] out = new char[l << 1];
    143        // two characters form the hex value.
    144        for (int i = 0, j = 0; i < l; i++) {
    145            out[j++] = toDigits[(0xF0 & data[i]) >>> 4];
    146            out[j++] = toDigits[0x0F & data[i]];
    147        }
    148        return out;
    149    }
    150
    151    /**
    152     * Converts an array of bytes into a String representing the hexadecimal values of each byte in order. The returned
    153     * String will be double the length of the passed array, as it takes two characters to represent any given byte.
    154     *
    155     * @param data
    156     *            a byte[] to convert to Hex characters
    157     * @return A String containing hexadecimal characters
    158     * @since 1.4
    159     */
    160    public static String encodeHexString(final byte[] data) {
    161        return new String(encodeHex(data));
    162    }
    163
    164    /**
    165     * Converts a hexadecimal character to an integer.
    166     *
    167     * @param ch
    168     *            A character to convert to an integer digit
    169     * @param index
    170     *            The index of the character in the source
    171     * @return An integer
    172     * @throws DecoderException
    173     *             Thrown if ch is an illegal hex character
    174     */
    175    protected static int toDigit(final char ch, final int index) throws DecoderException {
    176        final int digit = Character.digit(ch, 16);
    177        if (digit == -1) {
    178            throw new DecoderException("Illegal hexadecimal character " + ch + " at index " + index);
    179        }
    180        return digit;
    181    }
    182
    183    private final Charset charset;
    184
    185    /**
    186     * Creates a new codec with the default charset name {@link #DEFAULT_CHARSET}
    187     */
    188    public Hex() {
    189        // use default encoding
    190        this.charset = DEFAULT_CHARSET;
    191    }
    192
    193    /**
    194     * Creates a new codec with the given Charset.
    195     *
    196     * @param charset
    197     *            the charset.
    198     * @since 1.7
    199     */
    200    public Hex(final Charset charset) {
    201        this.charset = charset;
    202    }
    203
    204    /**
    205     * Creates a new codec with the given charset name.
    206     *
    207     * @param charsetName
    208     *            the charset name.
    209     * @throws java.nio.charset.UnsupportedCharsetException
    210     *             If the named charset is unavailable
    211     * @since 1.4
    212     * @since 1.7 throws UnsupportedCharsetException if the named charset is unavailable
    213     */
    214    public Hex(final String charsetName) {
    215        this(Charset.forName(charsetName));
    216    }
    217
    218    /**
    219     * Converts an array of character bytes representing hexadecimal values into an array of bytes of those same values.
    220     * The returned array will be half the length of the passed array, as it takes two characters to represent any given
    221     * byte. An exception is thrown if the passed char array has an odd number of elements.
    222     *
    223     * @param array
    224     *            An array of character bytes containing hexadecimal digits
    225     * @return A byte array containing binary data decoded from the supplied byte array (representing characters).
    226     * @throws DecoderException
    227     *             Thrown if an odd number of characters is supplied to this function
    228     * @see #decodeHex(char[])
    229     */
    230    @Override
    231    public byte[] decode(final byte[] array) throws DecoderException {
    232        return decodeHex(new String(array, getCharset()).toCharArray());
    233    }
    234
    235    /**
    236     * Converts a String or an array of character bytes representing hexadecimal values into an array of bytes of those
    237     * same values. The returned array will be half the length of the passed String or array, as it takes two characters
    238     * to represent any given byte. An exception is thrown if the passed char array has an odd number of elements.
    239     *
    240     * @param object
    241     *            A String or, an array of character bytes containing hexadecimal digits
    242     * @return A byte array containing binary data decoded from the supplied byte array (representing characters).
    243     * @throws DecoderException
    244     *             Thrown if an odd number of characters is supplied to this function or the object is not a String or
    245     *             char[]
    246     * @see #decodeHex(char[])
    247     */
    248    @Override
    249    public Object decode(final Object object) throws DecoderException {
    250        try {
    251            final char[] charArray = object instanceof String ? ((String) object).toCharArray() : (char[]) object;
    252            return decodeHex(charArray);
    253        } catch (final ClassCastException e) {
    254            throw new DecoderException(e.getMessage(), e);
    255        }
    256    }
    257
    258    /**
    259     * Converts an array of bytes into an array of bytes for the characters representing the hexadecimal values of each
    260     * byte in order. The returned array will be double the length of the passed array, as it takes two characters to
    261     * represent any given byte.
    262     * <p>
    263     * The conversion from hexadecimal characters to the returned bytes is performed with the charset named by
    264     * {@link #getCharset()}.
    265     * </p>
    266     *
    267     * @param array
    268     *            a byte[] to convert to Hex characters
    269     * @return A byte[] containing the bytes of the hexadecimal characters
    270     * @since 1.7 No longer throws IllegalStateException if the charsetName is invalid.
    271     * @see #encodeHex(byte[])
    272     */
    273    @Override
    274    public byte[] encode(final byte[] array) {
    275        return encodeHexString(array).getBytes(this.getCharset());
    276    }
    277
    278    /**
    279     * Converts a String or an array of bytes into an array of characters representing the hexadecimal values of each
    280     * byte in order. The returned array will be double the length of the passed String or array, as it takes two
    281     * characters to represent any given byte.
    282     * <p>
    283     * The conversion from hexadecimal characters to bytes to be encoded to performed with the charset named by
    284     * {@link #getCharset()}.
    285     * </p>
    286     *
    287     * @param object
    288     *            a String, or byte[] to convert to Hex characters
    289     * @return A char[] containing hexadecimal characters
    290     * @throws EncoderException
    291     *             Thrown if the given object is not a String or byte[]
    292     * @see #encodeHex(byte[])
    293     */
    294    @Override
    295    public Object encode(final Object object) throws EncoderException {
    296        try {
    297            final byte[] byteArray = object instanceof String ?
    298                                   ((String) object).getBytes(this.getCharset()) : (byte[]) object;
    299            return encodeHex(byteArray);
    300        } catch (final ClassCastException e) {
    301            throw new EncoderException(e.getMessage(), e);
    302        }
    303    }
    304
    305    /**
    306     * Gets the charset.
    307     *
    308     * @return the charset.
    309     * @since 1.7
    310     */
    311    public Charset getCharset() {
    312        return this.charset;
    313    }
    314
    315    /**
    316     * Gets the charset name.
    317     *
    318     * @return the charset name.
    319     * @since 1.4
    320     */
    321    public String getCharsetName() {
    322        return this.charset.name();
    323    }
    324
    325    /**
    326     * Returns a string representation of the object, which includes the charset name.
    327     *
    328     * @return a string representation of the object.
    329     */
    330    @Override
    331    public String toString() {
    332        return super.toString() + "[charsetName=" + this.charset + "]";
    333    }
    334}