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/*
 * 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.Charsets;
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 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 or illegal of characters is supplied
     * @since 1.11
     */
    public static byte[] decodeHex(final String data) throws DecoderException {
        return decodeHex(data.toCharArray());
    }

    /**
     * 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 or illegal of characters is supplied
     */
    public static byte[] decodeHex(final char[] data) throws DecoderException {

        final int len = data.length;

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

        final byte[] out = new byte[len >> 1];

        // two characters form the hex value.
        for (int i = 0, 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 out;
    }

    /**
     * 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 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.
     *
     * 

All bytes identified by {@link ByteBuffer#remaining()} will be used; after this method * the value {@link ByteBuffer#remaining() remaining()} will be zero.

* * @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 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 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. * *

All bytes identified by {@link ByteBuffer#remaining()} will be used; after this method * the value {@link ByteBuffer#remaining() remaining()} will be zero.

* * @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 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]; // two characters form the hex value. for (int i = 0, j = 0; i < l; i++) { out[j++] = toDigits[(0xF0 & data[i]) >>> 4]; out[j++] = toDigits[0x0F & data[i]]; } return out; } /** * 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. * *

All bytes identified by {@link ByteBuffer#remaining()} will be used; after this method * the value {@link ByteBuffer#remaining() remaining()} will be zero.

* * @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. * *

All bytes identified by {@link ByteBuffer#remaining()} will be used; after this method * the value {@link ByteBuffer#remaining() remaining()} will be zero.

* * @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. * *

All bytes identified by {@link ByteBuffer#remaining()} will be used; after this method * the value {@link ByteBuffer#remaining() remaining()} will be zero.

* * @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 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. * *

All bytes identified by {@link ByteBuffer#remaining()} will be used; after this method * the value {@link ByteBuffer#remaining() remaining()} will be zero.

* * @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. *

* The conversion from hexadecimal characters to the returned bytes is performed with the charset named by * {@link #getCharset()}. *

* * @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. * *

The conversion from hexadecimal characters to the returned bytes is performed with the charset named by * {@link #getCharset()}.

* *

All bytes identified by {@link ByteBuffer#remaining()} will be used; after this method * the value {@link ByteBuffer#remaining() remaining()} will be zero.

* * @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. *

* The conversion from hexadecimal characters to bytes to be encoded to performed with the charset named by * {@link #getCharset()}. *

* * @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 + "]"; } }




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