/**
     * Return a hex-dump formatted version of a byte array.
     */
    public static String hexDump(byte[] data)
    {
        StringBuffer result = new StringBuffer();
        StringBuffer line;
        int pos = 0;
        int max = data.length;
        if (data.length == 0)
            return "";
        while (pos < max)
        {
            int lineMax = Math.min(max-pos, 16);
            line = new StringBuffer();
            // Left half of the hex dump (binary digits)
            for (int i=0; i<lineMax; i++)
            {
                int b = data[pos+i];
                b = (b + 256) % 256;
                String code = Integer.toString(b, 16);
                if (b <= 0x0F)
                    line.append('0');
                line.append(code);
                line.append(' ');
            }
            while (line.length() < 48)
                line.append(' ');
            // Right half of the hex dump (character data)
            for (int i=0; i<lineMax; i++)
            {
                char c = (char)data[pos+i];
                if ((c < 32) || (c > 127))
                    c = '.';
                line.append(c);
            }
            line.append('\n');
            result.append(line);
            pos += 16;
        }
        return result.toString();
    }