    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
    018    package org.apache.commons.codec.binary;
    019
    020    import java.nio.charset.Charset;
    021
    022    import org.apache.commons.codec.BinaryDecoder;
    023    import org.apache.commons.codec.BinaryEncoder;
    024    import org.apache.commons.codec.CharEncoding;
    025    import org.apache.commons.codec.Charsets;
    026    import org.apache.commons.codec.DecoderException;
    027    import 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 1429868 2013-01-07 16:08:05Z ggregory $
    037     */
    038    public 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} converts to lowercase, {@code false} 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    }