.NET TimeZoneInfo from Olson time zone

Question

如何将以下内容转换为System.TimeZone或System.TimeZoneInfo？

{
  "timeZone": "America/Los_Angeles", 
  "currentOffsetMs": -25200000
}

这是我从第三方 Web 服务返回的数据。

我

假设偏移量是与UTC的差异，并且我被告知"美国/Los_Angeles"是奥尔森时区。Java将其解析为Java TimeZone没有问题，但是我需要将其解析为C# TimeZoneInfo对象。

Answer 1

此 Unicode.org 页面有一个"奥尔森时区到 Win32 时区"表。从那里，我创建了一个不错的小 C# 帮助程序函数，用于将 Olson 时区字符串映射到 .NET 时区信息：

/// <summary>
/// Converts an Olson time zone ID to a Windows time zone ID.
/// </summary>
/// <param name="olsonTimeZoneId">An Olson time zone ID. See http://unicode.org/repos/cldr-tmp/trunk/diff/supplemental/zone_tzid.html. </param>
/// <returns>
/// The TimeZoneInfo corresponding to the Olson time zone ID, 
/// or null if you passed in an invalid Olson time zone ID.
/// </returns>
/// <remarks>
/// See http://unicode.org/repos/cldr-tmp/trunk/diff/supplemental/zone_tzid.html
/// </remarks>
public static TimeZoneInfo OlsonTimeZoneToTimeZoneInfo(string olsonTimeZoneId)
{
    var olsonWindowsTimes = new Dictionary<string, string>()
    {
        { "Africa/Bangui", "W. Central Africa Standard Time" },
        { "Africa/Cairo", "Egypt Standard Time" },
        { "Africa/Casablanca", "Morocco Standard Time" },
        { "Africa/Harare", "South Africa Standard Time" },
        { "Africa/Johannesburg", "South Africa Standard Time" },
        { "Africa/Lagos", "W. Central Africa Standard Time" },
        { "Africa/Monrovia", "Greenwich Standard Time" },
        { "Africa/Nairobi", "E. Africa Standard Time" },
        { "Africa/Windhoek", "Namibia Standard Time" },
        { "America/Anchorage", "Alaskan Standard Time" },
        { "America/Argentina/San_Juan", "Argentina Standard Time" },
        { "America/Asuncion", "Paraguay Standard Time" },
        { "America/Bahia", "Bahia Standard Time" },
        { "America/Bogota", "SA Pacific Standard Time" },
        { "America/Buenos_Aires", "Argentina Standard Time" },
        { "America/Caracas", "Venezuela Standard Time" },
        { "America/Cayenne", "SA Eastern Standard Time" },
        { "America/Chicago", "Central Standard Time" },
        { "America/Chihuahua", "Mountain Standard Time (Mexico)" },
        { "America/Cuiaba", "Central Brazilian Standard Time" },
        { "America/Denver", "Mountain Standard Time" },
        { "America/Fortaleza", "SA Eastern Standard Time" },
        { "America/Godthab", "Greenland Standard Time" },
        { "America/Guatemala", "Central America Standard Time" },
        { "America/Halifax", "Atlantic Standard Time" },
        { "America/Indianapolis", "US Eastern Standard Time" },
        { "America/Indiana/Indianapolis", "US Eastern Standard Time" },
        { "America/La_Paz", "SA Western Standard Time" },
        { "America/Los_Angeles", "Pacific Standard Time" },
        { "America/Mexico_City", "Mexico Standard Time" },
        { "America/Montevideo", "Montevideo Standard Time" },
        { "America/New_York", "Eastern Standard Time" },
        { "America/Noronha", "UTC-02" },
        { "America/Phoenix", "US Mountain Standard Time" },
        { "America/Regina", "Canada Central Standard Time" },
        { "America/Santa_Isabel", "Pacific Standard Time (Mexico)" },
        { "America/Santiago", "Pacific SA Standard Time" },
        { "America/Sao_Paulo", "E. South America Standard Time" },
        { "America/St_Johns", "Newfoundland Standard Time" },
        { "America/Tijuana", "Pacific Standard Time" },
        { "Antarctica/McMurdo", "New Zealand Standard Time" },
        { "Atlantic/South_Georgia", "UTC-02" },
        { "Asia/Almaty", "Central Asia Standard Time" },
        { "Asia/Amman", "Jordan Standard Time" },
        { "Asia/Baghdad", "Arabic Standard Time" },
        { "Asia/Baku", "Azerbaijan Standard Time" },
        { "Asia/Bangkok", "SE Asia Standard Time" },
        { "Asia/Beirut", "Middle East Standard Time" },
        { "Asia/Calcutta", "India Standard Time" },
        { "Asia/Colombo", "Sri Lanka Standard Time" },
        { "Asia/Damascus", "Syria Standard Time" },
        { "Asia/Dhaka", "Bangladesh Standard Time" },
        { "Asia/Dubai", "Arabian Standard Time" },
        { "Asia/Irkutsk", "North Asia East Standard Time" },
        { "Asia/Jerusalem", "Israel Standard Time" },
        { "Asia/Kabul", "Afghanistan Standard Time" },
        { "Asia/Kamchatka", "Kamchatka Standard Time" },
        { "Asia/Karachi", "Pakistan Standard Time" },
        { "Asia/Katmandu", "Nepal Standard Time" },
        { "Asia/Kolkata", "India Standard Time" },
        { "Asia/Krasnoyarsk", "North Asia Standard Time" },
        { "Asia/Kuala_Lumpur", "Singapore Standard Time" },
        { "Asia/Kuwait", "Arab Standard Time" },
        { "Asia/Magadan", "Magadan Standard Time" },
        { "Asia/Muscat", "Arabian Standard Time" },
        { "Asia/Novosibirsk", "N. Central Asia Standard Time" },
        { "Asia/Oral", "West Asia Standard Time" },
        { "Asia/Rangoon", "Myanmar Standard Time" },
        { "Asia/Riyadh", "Arab Standard Time" },
        { "Asia/Seoul", "Korea Standard Time" },
        { "Asia/Shanghai", "China Standard Time" },
        { "Asia/Singapore", "Singapore Standard Time" },
        { "Asia/Taipei", "Taipei Standard Time" },
        { "Asia/Tashkent", "West Asia Standard Time" },
        { "Asia/Tbilisi", "Georgian Standard Time" },
        { "Asia/Tehran", "Iran Standard Time" },
        { "Asia/Tokyo", "Tokyo Standard Time" },
        { "Asia/Ulaanbaatar", "Ulaanbaatar Standard Time" },
        { "Asia/Vladivostok", "Vladivostok Standard Time" },
        { "Asia/Yakutsk", "Yakutsk Standard Time" },
        { "Asia/Yekaterinburg", "Ekaterinburg Standard Time" },
        { "Asia/Yerevan", "Armenian Standard Time" },
        { "Atlantic/Azores", "Azores Standard Time" },
        { "Atlantic/Cape_Verde", "Cape Verde Standard Time" },
        { "Atlantic/Reykjavik", "Greenwich Standard Time" },
        { "Australia/Adelaide", "Cen. Australia Standard Time" },
        { "Australia/Brisbane", "E. Australia Standard Time" },
        { "Australia/Darwin", "AUS Central Standard Time" },
        { "Australia/Hobart", "Tasmania Standard Time" },
        { "Australia/Perth", "W. Australia Standard Time" },
        { "Australia/Sydney", "AUS Eastern Standard Time" },
        { "Etc/GMT", "UTC" },
        { "Etc/GMT+11", "UTC-11" },
        { "Etc/GMT+12", "Dateline Standard Time" },
        { "Etc/GMT+2", "UTC-02" },
        { "Etc/GMT-12", "UTC+12" },
        { "Europe/Amsterdam", "W. Europe Standard Time" },
        { "Europe/Athens", "GTB Standard Time" },
        { "Europe/Belgrade", "Central Europe Standard Time" },
        { "Europe/Berlin", "W. Europe Standard Time" },
        { "Europe/Brussels", "Romance Standard Time" },
        { "Europe/Budapest", "Central Europe Standard Time" },
        { "Europe/Dublin", "GMT Standard Time" },
        { "Europe/Helsinki", "FLE Standard Time" },
        { "Europe/Istanbul", "GTB Standard Time" },
        { "Europe/Kiev", "FLE Standard Time" },
        { "Europe/London", "GMT Standard Time" },
        { "Europe/Minsk", "E. Europe Standard Time" },
        { "Europe/Moscow", "Russian Standard Time" },
        { "Europe/Paris", "Romance Standard Time" },
        { "Europe/Sarajevo", "Central European Standard Time" },
        { "Europe/Warsaw", "Central European Standard Time" },
        { "Indian/Mauritius", "Mauritius Standard Time" },
        { "Pacific/Apia", "Samoa Standard Time" },
        { "Pacific/Auckland", "New Zealand Standard Time" },
        { "Pacific/Fiji", "Fiji Standard Time" },
        { "Pacific/Guadalcanal", "Central Pacific Standard Time" },
        { "Pacific/Guam", "West Pacific Standard Time" },
        { "Pacific/Honolulu", "Hawaiian Standard Time" },
        { "Pacific/Pago_Pago", "UTC-11" },
        { "Pacific/Port_Moresby", "West Pacific Standard Time" },
        { "Pacific/Tongatapu", "Tonga Standard Time" }
    };
    var windowsTimeZoneId = default(string);
    var windowsTimeZone = default(TimeZoneInfo);
    if (olsonWindowsTimes.TryGetValue(olsonTimeZoneId, out windowsTimeZoneId))
    {
        try { windowsTimeZone = TimeZoneInfo.FindSystemTimeZoneById(windowsTimeZoneId); }
        catch (TimeZoneNotFoundException) { }
        catch (InvalidTimeZoneException) { }
    }
    return windowsTimeZone;
}

Answer 2

下面是

使用NodaTime的反向映射（tzdb -> windows）函数：

using NodaTime;
using NodaTime.TimeZones;
...
public TimeZoneInfo GetTimeZoneInfoForTzdbId(string tzdbId)
{
  var mappings = TzdbDateTimeZoneSource.Default.WindowsMapping.MapZones;
  var map = mappings.FirstOrDefault(x =>
      x.TzdbIds.Any(z => z.Equals(tzdbId, StringComparison.OrdinalIgnoreCase)));
  return map == null ? null : TimeZoneInfo.FindSystemTimeZoneById(map.WindowsId);
}

请注意，可能存在多个映射（在这种情况下，这只使用找到的第一个映射），或者根本没有映射（返回 null）。

在最常用的时区中，这应该足够好。 但更好的解决方案是完全跳过使用TimeZoneInfo，而在整个应用程序中直接使用NodaTime，直接使用您拥有的TZDB区域。

另请参阅：如何在 Windows 和 IANA 时区之间进行翻译？

Answer 3

你可能想看看Jon Skeet的Noda-Time，完全放弃TimeZoneInfo。Noda-Time使用奥尔森时区，因此您的映射将是小菜一碟。您可能想要使用它还有其他原因：

日期时间到底有什么问题？

所以我的问题，其结果是使用野田时间

Answer 4

我想

出了一个小片段，用于从 xml 获取 olson 到 Windows 时区映射的列表 http://unicode.org/repos/cldr/trunk/common/supplemental/windowsZones.xml

private static void LoadMappingsO()
{
    var file = new FileInfo("windowsZones.xml");
    if (!file.Exists)
    {
        return;
    }
    var map = new Dictionary<string, string>();
    using (var reader = file.OpenText())
    {
        var readerSettings = new XmlReaderSettings { XmlResolver = null, ProhibitDtd = false };
        using (var xmlReader = XmlReader.Create(reader, readerSettings))
        {
            var document = new XPathDocument(xmlReader);
            var navigator = document.CreateNavigator();
            var nodes = navigator.Select("/supplementalData/windowsZones/mapTimezones/mapZone");
            while (nodes.MoveNext())
            {
                var node = nodes.Current;
                if (node == null) continue;
                var olsonNames = node.GetAttribute("type", "").Split(' ');
                var windowsName = node.GetAttribute("other", "");
                foreach (var olsonName in olsonNames)
                {
                    if (!map.ContainsKey(olsonName))
                    {
                        map.Add(olsonName, windowsName);
                    }
                }
            }
        }
    }
    using (TextWriter tw = new StreamWriter("dict.txt", false))
    {
        foreach (var key in map.Keys)
        {
            tw.WriteLine(string.Format("{{"{0}", "{1}"}},", key, map[key]));
        }
    }
}

UPDATE（使用 Linq XML）：

private static void LoadMappings()
{
    var map = new Dictionary<string, string>();
    var xdoc = XDocument.Load("windowsZones.xml");
    var zones = xdoc.XPathSelectElements("/supplementalData/windowsZones/mapTimezones/mapZone");
    foreach (var zone in zones)
    {
        var olsonNames = zone.Attribute("type")?.Value.Split(' ');
        if (olsonNames == null)
            continue;
        var windowsName = zone.Attribute("other")?.Value;
        if (string.IsNullOrWhiteSpace(windowsName))
            continue;
        foreach (var olsonName in olsonNames)
        {
            map[olsonName] = windowsName;
        }
    }
    using (TextWriter tw = new StreamWriter("dict.txt", false))
    {
        foreach (var key in map.Keys)
        {
            tw.WriteLine($"{{"{key}", "{map[key]}"}},");
        }
    }
}

Answer 5

更新：我已经从脚本中删除了 URL。请手动获取文件。此脚本并非旨在不断运行，给 unicode.org 带来不必要的负载。请参阅下面的评论。

此 Powershell 脚本可用于使用 unicode.org 中的当前 XML 文件生成案例语句。它生成从IANA名称到TimeZoneInfoId的映射。

    # Download the xml file.
    $xml = [Xml] /// Load the XML content here
    # Parse the fields we want from the XML.
    $mappings1 = $xml.supplementalData.windowsZones.mapTimezones.mapZone | select Type,Other 
    # Extrapolate extra rows for entries that contain more than one IANA name seperated by spaces.
    # Example: |<mapZone other="Alaskan Standard Time" territory="US" type="America/Anchorage America/Juneau America/Nome America/Sitka America/Yakutat"/>
    $mappings2 = $mappings1 | %{
        $mapping = $_
        $_.Type.Split(" ") | %{
            New-Object PSObject -Property @{type = $_; other = $mapping.other}
        }  
    }
    # Remove dup's
    $mappings3 = $mappings2 | sort type -Unique
    # Generate the case statements.
    $mappings3 | %{ [String]::Format("case @""{0}"": return @""{1}"";", $_.Type, $_.Other)}

Answer 6

将当前偏移量转换为小时和剩余分钟数后，可以枚举定义的时区信息对象：

foreach (TimeZoneInfo nextZone in TimeZoneInfo.GetSystemTimeZones())
{
    int nextHours = nextZone.BaseUtcOffset.Hours + 24;     // To prevent negative numbers
    int nextMinutes = nextZone.BaseUtcOffset.Minutes;
    if (tzHours == nextHours && tzMinutes == nextMinutes)
    {
        myTimeZoneInfo = nextZone;
        break;
    }
}