DateTime & UTC 相互转化

public long ToUnixTime(DateTime date)
{
　　var epoch = new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc);
　　return Convert.ToInt64((date.ToUniversalTime() - epoch).TotalMilliseconds);
}

public static System.DateTime ConvertIntDateTime(double utc)
{
　　System.DateTime startTime = TimeZone.CurrentTimeZone.ToLocalTime(new System.DateTime(1970, 1, 1, 0, 0, 0));
　　return startTime.AddMilliseconds(utc);
}