十六进制与字符串互转

 /// <summary>
    /// 从16进制转换成汉字
    /// </summary>
    /// <param name="hex"></param>
    /// <returns></returns>
    public string GetHexUncode(string hex)
    {
        if (hex == null)
            throw new ArgumentNullException("hex");
        if (hex.Length % 2 != 0)
        {
            hex += "20";//空格
        }
        // 需要将 hex 转换成 byte 数组。
        byte[] bytes = new byte[hex.Length / 2];
        for (int i = 0; i < bytes.Length; i++)
        {
            try
            {
                // 每两个字符是一个 byte。
                bytes[i] = byte.Parse(hex.Substring(i * 2, 2),
                    System.Globalization.NumberStyles.HexNumber);
            }
            catch
            {
                throw new ArgumentException("hex is not a valid hex number!", "hex");
            }
        }
        // 获得 GB2312，Chinese Simplified。
        System.Text.Encoding chs = System.Text.Encoding.GetEncoding("gb2312");
        return chs.GetString(bytes);
    }

    /// <summary>
    /// 从汉字转换到16进制
    /// </summary>
    /// <param name="s"></param>
    /// <returns></returns>
    public static string GetHexEncode(string s)
    {
        if ((s.Length % 2) != 0)
        {
            s += " ";//空格
        }
        System.Text.Encoding chs = System.Text.Encoding.GetEncoding("gb2312");
        byte[] bytes = chs.GetBytes(s);
        string str = "";
        for (int i = 0; i < bytes.Length; i++)
        {
            str += string.Format("{0:X}", bytes[i]);
        }
        return str;
    }