如何获取具有本地时间信息的日期时间偏移量

Question

我有这些输入字符串：

var timeStr = "03:22";
var dateStr = "2018/01/12";
var format = "yyyy/MM/dd";
var timeZone = "Asia/Tehran";

这是我拥有的时间信息，timeStr在Asia/Tehran时区而不是UTC时区。

使用 NodaTime，我怎样才能获得一个包含正确偏移量的信息的 DateTimeOffset 对象？

Answer 1

让我们将所有信息转换为适当的 Noda 时间类型：

// Input values (as per the question)
var timeStr = "03:22";
var dateStr = "2018/01/12";
var format = "yyyy/MM/dd";
var timeZone = "Asia/Tehran";
// The patterns we'll use to parse input values
LocalTimePattern timePattern = LocalTimePattern.CreateWithInvariantCulture("HH:mm");
LocalDatePattern datePattern = LocalDatePattern.CreateWithInvariantCulture(format);
// The local parts, parsed with the patterns and then combined.
// Note that this will throw an exception if the values can't be parsed -
// use the ParseResult<T> return from Parse to check for success before
// using Value if you want to avoid throwing.
LocalTime localTime = timePattern.Parse(timeStr).Value;
LocalDate localDate = datePattern.Parse(dateStr).Value;
LocalDateTime localDateTime = localDate + localTime;
// Now get the time zone by ID
DateTimeZone zone = DateTimeZoneProviders.Tzdb[timeZone];
// Work out the zoned date/time being represented by the local date/time. See below for the "leniently" part.
ZonedDateTime zonedDateTime = localDateTime.InZoneLeniently(zone);
// The Noda Time type you want would be OffsetDateTime
OffsetDateTime offsetDateTime = zonedDateTime.ToOffsetDateTime();
// If you really want the BCL type...
DateTimeOffset dateTimeOffset = zonedDateTime.ToDateTimeOffset();

请注意"InZoneLeniently"，它处理不明确或跳过的本地日期/时间值，如下所示：

不明确的值映射到较早的备选方案，"跳过"的值按"间隙"的持续时间向前移动。

这可能是你想要的，也可能是你想要的。还有InZoneStrictly，如果给定的本地日期/时间没有表示一个时刻，或者您可以调用InZone并传入您自己的ZoneLocalMappingResolver，则会引发异常。

Answer 2

如果你正在寻找nodatime DateTimeOffset对象，你可以这样做：

var timeStr = "03:22";
var dateStr = "2018/01/12";
// DateTime.Parse can deal with this format without specs            
// var format = "yyyy/MM/dd";
var timeZone = "Asia/Tehran";

var date = DateTime.Parse(timeStr + " " + dateStr);
var zone = DateTimeZoneProviders.Tzdb[timeZone];
var timespanOffset = zone.GetUtcOffset(SystemClock.Instance.Now).ToTimeSpan();
var result = new DateTimeOffset(date, timespanOffset);
Console.Write(result.ToUniversalTime());

其结果是 ：1/11/2018 10:52:00 PM +00:00对应于德黑兰时间 GMT +4,5