com.ericsson.research.trap.utils.HexConverter Maven / Gradle / Ivy

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package com.ericsson.research.trap.utils;

/*
 * ##_BEGIN_LICENSE_##
 * Transport Abstraction Package (trap)
 * ----------
 * Copyright (C) 2014 Ericsson AB
 * ----------
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
 * 
 * 1. Redistributions of source code must retain the above copyright notice, this
 *    list of conditions and the following disclaimer.
 * 
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 * 
 * 3. Neither the name of the Ericsson AB nor the names of its contributors
 *    may be used to endorse or promote products derived from this software without
 *    specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
 * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 * ##_END_LICENSE_##
 */

/**
 * Converts bytes to/from hexadecimal format. The string is not prefixed with anything. Hexadecimal format is a verbose
 * representation of binary data, but is an extremely easy coding to do, making it useful for ASCII-safe transportation
 * of small (<32 bytes) amounts of data.
 * 
 * @author Vladimir Katardjiev
 * @since 1.1
 */
public class HexConverter
{
    /**
     * Converts a string containing a hexadecimal representation to the requisite bytes.
     * 
     * @param s
     *            A string comprised of only valid hexadecimal input, of an even length.
     * @return The byte representation of the string
     * @throws ArrayIndexOutOfBoundsException
     *             If the string is an odd length.
     */
    public static byte[] toByteArray(String s)
    {
        int len = s.length();
        byte[] data = new byte[len / 2];
        for (int i = 0; i < len; i += 2)
        {
            data[i / 2] = (byte) ((Character.digit(s.charAt(i), 16) << 4) + Character.digit(s.charAt(i + 1), 16));
        }
        return data;
    }
    
    /**
     * Converts a byte array to its hexadecimal representation
     * 
     * @param bs
     *            The byte array to convert
     * @return The hexadecimal string
     */
    public static String toString(byte[] bs)
    {
        StringBuilder sb = new StringBuilder(bs.length * 2);
        
        for (int i = 0; i < bs.length; i++)
        {
            byte b = bs[i];
            sb.append(Character.forDigit((b >> 4) & 0xF, 16));
            sb.append(Character.forDigit(b & 0xF, 16));
        }
        
        return sb.toString();
    }
    
    private HexConverter(){}
}