根据我的理解,阅读this link at the nodatime google group,将一个ZonedDateTime转换为另一个时区(使用WithZone)是相当简单的(一旦我将用户的事件从LocalDateTime映射到ZonedDateTime,显然).我不需要担心抵消,比如Pheonix和芝加哥之间的夏令时差异将得到恰当的考虑.
我最初将服务器的时间(DateTime.Now)转换为ZonedDateTime并以此方式进行比较,但在阅读this link on SO之后,我切换到使用IClock.
到目前为止,在测试中一切正在发挥作用,但我担心我可能没有测试的极端情况.根据NodaTime的文档：
The biggest “gotcha” is converting
LocalDateTimetoZonedDateTime– it has some corner cases you need to consider.
我已经仔细阅读了文档,并且我认为这个问题涉及一年中那些不会发生或发生两次的时间.这些时间永远不会被设置为我们用户的事件时间,但我确实使用了LenientResolver.还有其他陷阱 – 当我从LocalDateTime转换为ZonedDateTime时,我是否遗漏了任何东西,或者夏令时最终会困扰我？
另外,我需要在比较之前将用户的ZonedDateTime转换为服务器时区(我现在正在做)或者这是不必要的(甚至是错误的)步骤吗？如果我将事件的未转换ZonedDateTime(而不是转换到服务器时区后的事件的ZonedDateTime)与当前服务器ZonedDateTime进行比较,NodaTime是否能够正确比较(没有夏令时问题)(参见下面的代码,第三行到最后一行)？当单步执行代码时,我可以看到时间和偏移量,但我担心这样做可能会导致问题过于简单化.
Protected Function EventIsReady(ByVal insTimeZone As String,ByVal eventDate As DateTime) As Boolean
Dim clock As IClock = SystemClock.Instance
Dim now As Instant = clock.Now
'server time zone (America/Chicago),unfortunately not UTC
Dim zone = DateTimeZoneProviders.Tzdb("America/Chicago")
Dim serverZonedDateTime = now.InZone(zone)
'user time zone
Dim userTimeZone As NodaTime.DateTimeZone = NodaTime.DateTimeZoneProviders.Tzdb.GetZoneOrNull(insTimeZone)
Dim userEventLocalDateTime = LocalDateTime.FromDateTime(eventDate)
Dim eventZonedDateTime = userTimeZone.ResolveLocal(userEventLocalDateTime,Resolvers.LenientResolver)
Dim eventTimeInServerTimeZone = eventZonedDateTime.WithZone(zone)
Dim isReady As Boolean = False
If eventTimeInServerTimeZone >= serverZonedDateTime Then
isReady = True
End If
Return isReady
End Function
关于LenientResolver,请确保您了解其行为.它使用ReturnStartOfIntervalAfter作为弹跳间隙,使用ReturnLater作为后退重叠.
恕我直言,这不是安排未来事件的最佳配置. (见Issue #295),试试这个：
VB.NET
Public Shared ReadOnly SchedulingResolver As ZoneLocalMappingResolver = _
Resolvers.CreateMappingResolver(Resolvers.ReturnEarlier,_
AddressOf ReturnForwardShifted)
Public Shared Function ReturnForwardShifted(local As LocalDateTime,_
zone As DateTimeZone,before As ZoneInterval,after As ZoneInterval) _
As ZonedDateTime
Dim newLocal As LocalDateTime = local.PlusTicks(after.Savings.Ticks)
Return New ZonedDateTime(newLocal,zone,after.WallOffset)
End Function
C#
public static readonly ZoneLocalMappingResolver SchedulingResolver =
Resolvers.CreateMappingResolver(Resolvers.ReturnEarlier,ReturnForwardShifted);
public static ZonedDateTime ReturnForwardShifted(LocalDateTime local,DateTimeZone zone,ZoneInterval before,ZoneInterval after)
{
LocalDateTime newLocal = local.PlusTicks(after.Savings.Ticks);
return new ZonedDateTime(newLocal,after.WallOffset);
}
关于服务器的时区 – 您应该将其从代码中删除.您的代码不应该关心服务器的时区.相反,在ZonedDateTime(您的eventZonedDateTime变量)上调用ToInstant(),然后将其与从clock.Now返回的Instant进行比较.