C#本地时间和GMT(UTC)时间的转换

        /// <summary>
        /// 本地时间转成GMT时间
        /// </summary>
        public static string ToGMTString(DateTime dt)
        {
            return dt.ToUniversalTime().ToString("r");
        }
        string s = ToGMTString(DateTime.Now);
        //本地时间为：2016-6-30 10:04:39
        //转换后的时间为：Thu, 30 Jun 2016 2:04:39 GMT


        /// <summary>
        /// 本地时间转成GMT格式的时间
        /// </summary>
        public static string ToGMTFormat(DateTime dt)
        {
            return dt.ToString("r") + dt.ToString("zzz").Replace(":", "");
        }
        string s = ToGMTFormat(DateTime.Now);
        //本地时间为：2016-6-30 10:04:39
        //转换后的时间为：Thu, 30 Jun 2016 10:04:39 GMT+0800

        /// <summary>
        /// GMT时间转成本地时间
        /// </summary>
        /// <param name="gmt">字符串形式的GMT时间</param>
        /// <returns></returns>
        public static DateTime GMT2Local(string gmt)
        {
            DateTime dt = DateTime.MinValue;
            try
            {
                string pattern = "";
         )
         {
                    gmt = gmt.Replace("GMT", "");
                    pattern = "ddd, dd MMM yyyy HH':'mm':'ss zzz";
                }
         )
         {
                    pattern = "ddd, dd MMM yyyy HH':'mm':'ss 'GMT'";
                }
                if (pattern != "")
                {
                    dt = DateTime.ParseExact(gmt, pattern, System.Globalization.CultureInfo.InvariantCulture, System.Globalization.DateTimeStyles.AdjustToUniversal);
                    dt = dt.ToLocalTime();
                }
                else
                {
                    dt = Convert.ToDateTime(gmt);
                }
            }
            catch
            {
            }
            return dt;
        }
        DateTime dt1 = GMT2Local("Thu, 30 Jun 2016 02:04:39 GMT");
        //转换后的dt1为：2016-6-30 10:04:39
        DateTime dt2 = GMT2Local("Thu, 30 Jun 2016 10:04:39 GMT+0800");
        //转换后的dt2为：2016-6-30 10:04:39