鉴于:
DateTime.UtcNow
如何获得符合ISO 8601格式的相同值的字符串？
请注意,ISO 8601定义了许多类似的格式.我正在寻找的具体格式是:
yyyy-MM-ddTHH:mm:ssZ
Wayne.. 739
DateTime.UtcNow.ToString("yyyy-MM-ddTHH\\:mm\\:ss.fffffffzzz");
这会给你一个类似于2008-09-22T13:57:31.2311892-04:00的日期.
另一种方式是:
DateTime.UtcNow.ToString("o");
哪个给你2008-09-22T14:01:54.9571247Z
要获取指定的格式,您可以使用:
DateTime.UtcNow.ToString("yyyy-MM-ddTHH:mm:ssZ")
日期时间格式选项
DateTime.UtcNow.ToString("yyyy-MM-ddTHH\\:mm\\:ss.fffffffzzz");
这会给你一个类似于2008-09-22T13:57:31.2311892-04:00的日期.
另一种方式是:
DateTime.UtcNow.ToString("o");
哪个给你2008-09-22T14:01:54.9571247Z
要获取指定的格式,您可以使用:
DateTime.UtcNow.ToString("yyyy-MM-ddTHH:mm:ssZ")
日期时间格式选项
DateTime.UtcNow.ToString("s", System.Globalization.CultureInfo.InvariantCulture)应该给你你想要的东西,因为"s"格式说明符被描述为一个可排序的日期/时间模式; 符合ISO 8601.
DateTime.UtcNow.ToString("s")
返回类似2008-04-10T06:30:00的内容
UtcNow显然会返回UTC时间,所以在以下方面没有任何危害:
string.Concat(DateTime.UtcNow.ToString("s"), "Z")
使用:
private void TimeFormats()
{
DateTime localTime = DateTime.Now;
DateTime utcTime = DateTime.UtcNow;
DateTimeOffset localTimeAndOffset = new DateTimeOffset(localTime, TimeZoneInfo.Local.GetUtcOffset(localTime));
//UTC
string strUtcTime_o = utcTime.ToString("o");
string strUtcTime_s = utcTime.ToString("s");
string strUtcTime_custom = utcTime.ToString("yyyy-MM-ddTHH:mm:ssK");
//Local
string strLocalTimeAndOffset_o = localTimeAndOffset.ToString("o");
string strLocalTimeAndOffset_s = localTimeAndOffset.ToString("s");
string strLocalTimeAndOffset_custom = utcTime.ToString("yyyy-MM-ddTHH:mm:ssK");
//Output
Response.Write("
UTC
");
Response.Write("strUtcTime_o: " + strUtcTime_o + "
");
Response.Write("strUtcTime_s: " + strUtcTime_s + "
");
Response.Write("strUtcTime_custom: " + strUtcTime_custom + "
");
Response.Write("
Local Time
");
Response.Write("strLocalTimeAndOffset_o: " + strLocalTimeAndOffset_o + "
");
Response.Write("strLocalTimeAndOffset_s: " + strLocalTimeAndOffset_s + "
");
Response.Write("strLocalTimeAndOffset_custom: " + strLocalTimeAndOffset_custom + "
");
}
UTC
strUtcTime_o: 2012-09-17T22:02:51.4021600Z
strUtcTime_s: 2012-09-17T22:02:51
strUtcTime_custom: 2012-09-17T22:02:51Z
Local Time
strLocalTimeAndOffset_o: 2012-09-17T15:02:51.4021600-07:00
strLocalTimeAndOffset_s: 2012-09-17T15:02:51
strLocalTimeAndOffset_custom: 2012-09-17T22:02:51Z
标准日期和时间格式字符串(MSDN)
自定义日期和时间格式字符串(MSDN)
System.DateTime.UtcNow.ToString("o")
=>
val it : string = "2013-10-13T13:03:50.2950037Z"
您可以使用下一个代码获得"Z"(ISO 8601 UTC):
Dim tmpDate As DateTime = New DateTime(Now.Ticks, DateTimeKind.Utc)
Dim res as String = tmpDate.toString("o") '2009-06-15T13:45:30.0000000Z
原因如下:
ISO 8601有一些不同的格式:
DateTimeKind.Local
2009-06-15T13:45:30.0000000-07:00
DateTimeKind.Utc
2009-06-15T13:45:30.0000000Z
DateTimeKind.Unspecified
2009-06-15T13:45:30.0000000
.NET为我们提供了这些选项的枚举:
'2009-06-15T13:45:30.0000000-07:00
Dim strTmp1 As String = New DateTime(Now.Ticks, DateTimeKind.Local).ToString("o")
'2009-06-15T13:45:30.0000000Z
Dim strTmp2 As String = New DateTime(Now.Ticks, DateTimeKind.Utc).ToString("o")
'2009-06-15T13:45:30.0000000
Dim strTmp3 As String = New DateTime(Now.Ticks, DateTimeKind.Unspecified).ToString("o")
注意:如果将Visual Studio 2008"监视实用程序"应用于toString("o")部分,您可能会得到不同的结果,我不知道它是否是一个错误,但在这种情况下,使用String变量可以获得更好的结果如果你正在调试
来源:标准日期和时间格式字符串(MSDN)
如果必须将DateTime用于ISO 8601,那么ToString("o")应该产生您要查找的内容.例如,
2015-07-06T12:08:27
但是,DateTime + TimeZone可能会出现其他问题,如.NET中的DateTime和DateTimeOffset博客中所述:良好实践和常见陷阱:
DateTime中有无数陷阱,旨在为您的代码提供错误:
1.- DateTimeKind.Unspecified的DateTime值是坏消息.
2.- DateTime在进行比较时不关心UTC/Local.
3.- DateTime值不知道标准格式字符串.
4.-使用DateTime解析具有UTC标记的字符串不保证UTC时间.
我会用XmlConvert:
XmlConvert.ToString(DateTime.UtcNow, XmlDateTimeSerializationMode.RoundtripKind);
它会自动保留时区.
大多数答案都有毫秒/微秒,ISO 8601显然不支持.正确的答案是:
System.DateTime.Now.ToString("yyyy-MM-ddTHH:mm:ssK");
// or
System.DateTime.Now.ToUniversalTime().ToString("yyyy-MM-ddTHH:mm:ssK");
参考文献:
ISO 8601规范
"K"说明符
DateTime.Now.ToString("yyyy-MM-dd'T'HH:mm:ss zzz");
DateTime.Now.ToString("O");
注意:根据您在最后进行的转换,您将使用第一行(最喜欢它)或第二行.
确保仅在本地时间应用格式,因为"zzz"是UTC转换的时区信息.
要将DateTime.UtcNow转换为yyyy-MM-ddTHH:mm:ssZ的字符串表示形式,可以将DateTime结构的ToString()方法与自定义格式字符串一起使用.将自定义格式字符串与DateTime一起使用时,请务必记住您需要使用单引号转义分隔符.
以下将返回您想要的字符串表示:
DateTime.UtcNow.ToString("yyyy'-'MM'-'dd'T'HH':'mm':'ss'Z'", DateTimeFormatInfo.InvariantInfo)
惊讶的是没有人建议：
System.DateTime.UtcNow.ToString("u").Replace(' ','T')
该UniversalSortableDateTimePattern让你几乎所有的方式给你想要的东西（这更多的是一个RFC 3339表示）。
补充：我决定使用答案/sf/ask/17360801/中的基准来比较其性能。
tl：dr; 这是在昂贵的一端。
实现方式：
[Benchmark]
public string ReplaceU()
{
var text = dateTime.ToUniversalTime().ToString("u").Replace(' ', 'T');
return text;
}
结果：
// * Summary * BenchmarkDotNet=v0.11.5, OS=Windows 10.0.19002 Intel Xeon CPU E3-1245 v3 3.40GHz, 1 CPU, 8 logical and 4 physical cores .NET Core SDK=3.0.100 [Host] : .NET Core 3.0.0 (CoreCLR 4.700.19.46205, CoreFX 4.700.19.46214), 64bit RyuJIT DefaultJob : .NET Core 3.0.0 (CoreCLR 4.700.19.46205, CoreFX 4.700.19.46214), 64bit RyuJIT | Method | Mean | Error | StdDev | |--------------------- |---------:|----------:|----------:| | CustomDev1 | 562.4 ns | 11.135 ns | 10.936 ns | | CustomDev2 | 525.3 ns | 3.322 ns | 3.107 ns | | CustomDev2WithMS | 609.9 ns | 9.427 ns | 8.356 ns | | FormatO | 356.6 ns | 6.008 ns | 5.620 ns | | FormatS | 589.3 ns | 7.012 ns | 6.216 ns | | FormatS_Verify | 599.8 ns | 12.054 ns | 11.275 ns | | CustomFormatK | 549.3 ns | 4.911 ns | 4.594 ns | | CustomFormatK_Verify | 539.9 ns | 2.917 ns | 2.436 ns | | ReplaceU | 615.5 ns | 12.313 ns | 11.517 ns | // * Hints * Outliers BenchmarkDateTimeFormat.CustomDev2WithMS: Default -> 1 outlier was removed (668.16 ns) BenchmarkDateTimeFormat.FormatS: Default -> 1 outlier was removed (621.28 ns) BenchmarkDateTimeFormat.CustomFormatK: Default -> 1 outlier was detected (542.55 ns) BenchmarkDateTimeFormat.CustomFormatK_Verify: Default -> 2 outliers were removed (557.07 ns, 560.95 ns) // * Legends * Mean : Arithmetic mean of all measurements Error : Half of 99.9% confidence interval StdDev : Standard deviation of all measurements 1 ns : 1 Nanosecond (0.000000001 sec) // ***** BenchmarkRunner: End *****
的
"s"标准格式说明代表在由定义的自定义的日期和时间的格式字符串DateTimeFormatInfo.SortableDateTimePattern属性.该模式反映了已定义的标准(ISO 8601),并且该属性是只读的.因此,无论使用何种文化或提供格式提供程序,它始终是相同的.自定义格式字符串是"yyyy'-'MM'-'dd'T'HH':'mm':'ss".使用此标准格式说明符时,格式化或解析操作始终使用不变文化.
- 来自MSDN
有趣的是,自定义格式"yyyy-MM-ddTHH:mm:ssK"(没有ms)是最快的格式方法.
另外有趣的是,"S"格式在Classic上很慢而在Core上很快......
当然数字非常接近,某些行之间的差异无关紧要(带后缀的测试与没有后缀的测试_Verify相同,显示结果可重复性)
BenchmarkDotNet=v0.10.5, OS=Windows 10.0.14393
Processor=Intel Core i5-2500K CPU 3.30GHz (Sandy Bridge), ProcessorCount=4
Frequency=3233539 Hz, Resolution=309.2587 ns, Timer=TSC
[Host] : Clr 4.0.30319.42000, 64bit RyuJIT-v4.6.1637.0
Clr : Clr 4.0.30319.42000, 64bit RyuJIT-v4.6.1637.0
Core : .NET Core 4.6.25009.03, 64bit RyuJIT
Method | Job | Runtime | Mean | Error | StdDev | Median | Min | Max | Rank | Gen 0 | Allocated |
--------------------- |----- |-------- |-----------:|----------:|----------:|-----------:|-----------:|-----------:|-----:|-------:|----------:|
CustomDev1 | Clr | Clr | 1,089.0 ns | 22.179 ns | 20.746 ns | 1,079.9 ns | 1,068.9 ns | 1,133.2 ns | 8 | 0.1086 | 424 B |
CustomDev2 | Clr | Clr | 1,032.3 ns | 19.897 ns | 21.289 ns | 1,024.7 ns | 1,000.3 ns | 1,072.0 ns | 7 | 0.1165 | 424 B |
CustomDev2WithMS | Clr | Clr | 1,168.2 ns | 16.543 ns | 15.474 ns | 1,168.5 ns | 1,149.3 ns | 1,189.2 ns | 10 | 0.1625 | 592 B |
FormatO | Clr | Clr | 1,563.7 ns | 31.244 ns | 54.721 ns | 1,532.5 ns | 1,497.8 ns | 1,703.5 ns | 14 | 0.2897 | 976 B |
FormatS | Clr | Clr | 1,243.5 ns | 24.615 ns | 31.130 ns | 1,229.3 ns | 1,200.6 ns | 1,324.2 ns | 13 | 0.2865 | 984 B |
FormatS_Verify | Clr | Clr | 1,217.6 ns | 11.486 ns | 10.744 ns | 1,216.2 ns | 1,205.5 ns | 1,244.3 ns | 12 | 0.2885 | 984 B |
CustomFormatK | Clr | Clr | 912.2 ns | 17.915 ns | 18.398 ns | 916.6 ns | 878.3 ns | 934.1 ns | 4 | 0.0629 | 240 B |
CustomFormatK_Verify | Clr | Clr | 894.0 ns | 3.877 ns | 3.626 ns | 893.8 ns | 885.1 ns | 900.0 ns | 3 | 0.0636 | 240 B |
CustomDev1 | Core | Core | 989.1 ns | 12.550 ns | 11.739 ns | 983.8 ns | 976.8 ns | 1,015.5 ns | 6 | 0.1101 | 423 B |
CustomDev2 | Core | Core | 964.3 ns | 18.826 ns | 23.809 ns | 954.1 ns | 935.5 ns | 1,015.6 ns | 5 | 0.1267 | 423 B |
CustomDev2WithMS | Core | Core | 1,136.0 ns | 21.914 ns | 27.714 ns | 1,138.1 ns | 1,099.9 ns | 1,200.2 ns | 9 | 0.1752 | 590 B |
FormatO | Core | Core | 1,201.5 ns | 16.262 ns | 15.211 ns | 1,202.3 ns | 1,178.2 ns | 1,225.5 ns | 11 | 0.0656 | 271 B |
FormatS | Core | Core | 993.5 ns | 19.272 ns | 24.372 ns | 999.4 ns | 954.2 ns | 1,029.5 ns | 6 | 0.0633 | 279 B |
FormatS_Verify | Core | Core | 1,003.1 ns | 17.577 ns | 16.442 ns | 1,009.2 ns | 976.1 ns | 1,024.3 ns | 6 | 0.0674 | 279 B |
CustomFormatK | Core | Core | 878.2 ns | 17.017 ns | 20.898 ns | 877.7 ns | 851.4 ns | 928.1 ns | 2 | 0.0555 | 215 B |
CustomFormatK_Verify | Core | Core | 863.6 ns | 3.968 ns | 3.712 ns | 863.0 ns | 858.6 ns | 870.8 ns | 1 | 0.0550 | 215 B |
码:
public class BenchmarkDateTimeFormat
{
public static DateTime dateTime = DateTime.Now;
[Benchmark]
public string CustomDev1()
{
var d = dateTime.ToUniversalTime();
var sb = new StringBuilder(20);
sb.Append(d.Year).Append("-");
if (d.Month <= 9)
sb.Append("0");
sb.Append(d.Month).Append("-");
if (d.Day <= 9)
sb.Append("0");
sb.Append(d.Day).Append("T");
if (d.Hour <= 9)
sb.Append("0");
sb.Append(d.Hour).Append(":");
if (d.Minute <= 9)
sb.Append("0");
sb.Append(d.Minute).Append(":");
if (d.Second <= 9)
sb.Append("0");
sb.Append(d.Second).Append("Z");
var text = sb.ToString();
return text;
}
[Benchmark]
public string CustomDev2()
{
var u = dateTime.ToUniversalTime();
var sb = new StringBuilder(20);
var y = u.Year;
var d = u.Day;
var M = u.Month;
var h = u.Hour;
var m = u.Minute;
var s = u.Second;
sb.Append(y).Append("-");
if (M <= 9)
sb.Append("0");
sb.Append(M).Append("-");
if (d <= 9)
sb.Append("0");
sb.Append(d).Append("T");
if (h <= 9)
sb.Append("0");
sb.Append(h).Append(":");
if (m <= 9)
sb.Append("0");
sb.Append(m).Append(":");
if (s <= 9)
sb.Append("0");
sb.Append(s).Append("Z");
var text = sb.ToString();
return text;
}
[Benchmark]
public string CustomDev2WithMS()
{
var u = dateTime.ToUniversalTime();
var sb = new StringBuilder(23);
var y = u.Year;
var d = u.Day;
var M = u.Month;
var h = u.Hour;
var m = u.Minute;
var s = u.Second;
var ms = u.Millisecond;
sb.Append(y).Append("-");
if (M <= 9)
sb.Append("0");
sb.Append(M).Append("-");
if (d <= 9)
sb.Append("0");
sb.Append(d).Append("T");
if (h <= 9)
sb.Append("0");
sb.Append(h).Append(":");
if (m <= 9)
sb.Append("0");
sb.Append(m).Append(":");
if (s <= 9)
sb.Append("0");
sb.Append(s).Append(".");
sb.Append(ms).Append("Z");
var text = sb.ToString();
return text;
}
[Benchmark]
public string FormatO()
{
var text = dateTime.ToUniversalTime().ToString("o");
return text;
}
[Benchmark]
public string FormatS()
{
var text = string.Concat(dateTime.ToUniversalTime().ToString("s"),"Z");
return text;
}
[Benchmark]
public string FormatS_Verify()
{
var text = string.Concat(dateTime.ToUniversalTime().ToString("s"), "Z");
return text;
}
[Benchmark]
public string CustomFormatK()
{
var text = dateTime.ToUniversalTime().ToString("yyyy-MM-ddTHH:mm:ssK");
return text;
}
[Benchmark]
public string CustomFormatK_Verify()
{
var text = dateTime.ToUniversalTime().ToString("yyyy-MM-ddTHH:mm:ssK");
return text;
}
}
https://github.com/dotnet/BenchmarkDotNet使用
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