c# UTF-8转gb2312

/// <summary>
        /// UTF8转换成GB2312
        /// </summary>
        /// <param name="text"></param>
        /// <returns></returns>
        public static string UTF8ToGB2312(string str)
        {
            try
            {
                Encoding utf8 = Encoding.UTF8;
                Encoding gb2312 = Encoding.GetEncoding("gb2312");//Encoding.Default ,936
                byte[] temp = utf8.GetBytes(str);
                byte[] temp1 = Encoding.Convert(utf8, gb2312, temp);
                string result = gb2312.GetString(temp1);
                return result;
            }
            catch
            {
                return null;
            }
        }