DateTime.SpecifyKind(DateTime, DateTimeKind) 方法

定义

创建新的 DateTime 对象,该对象具有与指定的 DateTime 相同的刻度数,但是根据指定的 DateTimeKind 值的指示,指定为本地时间或协调世界时 (UTC),或者两者皆否。

public:
 static DateTime SpecifyKind(DateTime value, DateTimeKind kind);
public static DateTime SpecifyKind (DateTime value, DateTimeKind kind);
static member SpecifyKind : DateTime * DateTimeKind -> DateTime
Public Shared Function SpecifyKind (value As DateTime, kind As DateTimeKind) As DateTime

参数

value
DateTime

日期和时间。

kind
DateTimeKind

枚举值之一,该值指示新对象是表示本地时间、UTC,还是两者皆否。

返回

DateTime

一个新对象,它与由 value 参数和由 DateTimeKind 参数指定的 kind 值代表的对象具有相同刻度数。

示例

以下示例使用该方法SpecifyKind演示属性如何影响KindToLocalTimeToUniversalTime转换方法。

// This code example demonstrates the DateTime Kind, Now, and
// UtcNow properties, and the SpecifyKind(), ToLocalTime(),
// and ToUniversalTime() methods.

open System

// Display the value and Kind property of a DateTime structure, the
// DateTime structure converted to local time, and the DateTime
// structure converted to universal time.

let datePatt = @"M/d/yyyy hh:mm:ss tt"

let display title (inputDt: DateTime) =
    // Display the original DateTime.

    let dispDt = inputDt
    let dtString = dispDt.ToString datePatt
    printfn $"%s{title} {dtString}, Kind = {dispDt.Kind}"

    // Convert inputDt to local time and display the result.
    // If inputDt.Kind is DateTimeKind.Utc, the conversion is performed.
    // If inputDt.Kind is DateTimeKind.Local, the conversion is not performed.
    // If inputDt.Kind is DateTimeKind.Unspecified, the conversion is
    // performed as if inputDt was universal time.

    let dispDt = inputDt.ToLocalTime()
    let dtString = dispDt.ToString datePatt
    printfn $"  ToLocalTime:     {dtString}, Kind = {dispDt.Kind}"

    // Convert inputDt to universal time and display the result.
    // If inputDt.Kind is DateTimeKind.Utc, the conversion is not performed.
    // If inputDt.Kind is DateTimeKind.Local, the conversion is performed.
    // If inputDt.Kind is DateTimeKind.Unspecified, the conversion is
    // performed as if inputDt was local time.

    let dispDt = inputDt.ToUniversalTime()
    let dtString = dispDt.ToString datePatt
    printfn $"  ToUniversalTime: {dtString}, Kind = {dispDt.Kind}\n" 

    // Display the value and Kind property for DateTime.Now and DateTime.UtcNow.

let displayNow title (inputDt: DateTime) =
    let dtString = inputDt.ToString datePatt
    printfn $"%s{title} {dtString}, Kind = {inputDt.Kind}"

[<EntryPoint>]
let main _ =

    // Get the date and time for the current moment, adjusted
    // to the local time zone.

    let saveNow = DateTime.Now

    // Get the date and time for the current moment expressed
    // as coordinated universal time (UTC).

    let saveUtcNow = DateTime.UtcNow

    // Display the value and Kind property of the current moment
    // expressed as UTC and local time.

    displayNow "UtcNow: .........." saveUtcNow
    displayNow "Now: ............." saveNow
    printfn ""

    // Change the Kind property of the current moment to
    // DateTimeKind.Utc and display the result.

    let myDt = DateTime.SpecifyKind(saveNow, DateTimeKind.Utc)
    display "Utc: ............." myDt

    // Change the Kind property of the current moment to
    // DateTimeKind.Local and display the result.

    let myDt = DateTime.SpecifyKind(saveNow, DateTimeKind.Local)
    display "Local: ..........." myDt

    // Change the Kind property of the current moment to
    // DateTimeKind.Unspecified and display the result.

    let myDt = DateTime.SpecifyKind(saveNow, DateTimeKind.Unspecified)
    display "Unspecified: ....." myDt

    0


// This code example produces the following results:
//
// UtcNow: .......... 5/6/2005 09:34:42 PM, Kind = Utc
// Now: ............. 5/6/2005 02:34:42 PM, Kind = Local
//
// Utc: ............. 5/6/2005 02:34:42 PM, Kind = Utc
//   ToLocalTime:     5/6/2005 07:34:42 AM, Kind = Local
//   ToUniversalTime: 5/6/2005 02:34:42 PM, Kind = Utc
//
// Local: ........... 5/6/2005 02:34:42 PM, Kind = Local
//   ToLocalTime:     5/6/2005 02:34:42 PM, Kind = Local
//   ToUniversalTime: 5/6/2005 09:34:42 PM, Kind = Utc
//
// Unspecified: ..... 5/6/2005 02:34:42 PM, Kind = Unspecified
//   ToLocalTime:     5/6/2005 07:34:42 AM, Kind = Local
//   ToUniversalTime: 5/6/2005 09:34:42 PM, Kind = Utc
// This code example demonstrates the DateTime Kind, Now, and
// UtcNow properties, and the SpecifyKind(), ToLocalTime(),
// and ToUniversalTime() methods.

using System;

class Sample
{
    public static void Main()
    {
// Get the date and time for the current moment, adjusted
// to the local time zone.

    DateTime saveNow = DateTime.Now;

// Get the date and time for the current moment expressed
// as coordinated universal time (UTC).

    DateTime saveUtcNow = DateTime.UtcNow;
    DateTime myDt;

// Display the value and Kind property of the current moment
// expressed as UTC and local time.

    DisplayNow("UtcNow: ..........", saveUtcNow);
    DisplayNow("Now: .............", saveNow);
    Console.WriteLine();

// Change the Kind property of the current moment to
// DateTimeKind.Utc and display the result.

    myDt = DateTime.SpecifyKind(saveNow, DateTimeKind.Utc);
    Display("Utc: .............", myDt);

// Change the Kind property of the current moment to
// DateTimeKind.Local and display the result.

    myDt = DateTime.SpecifyKind(saveNow, DateTimeKind.Local);
    Display("Local: ...........", myDt);

// Change the Kind property of the current moment to
// DateTimeKind.Unspecified and display the result.

    myDt = DateTime.SpecifyKind(saveNow, DateTimeKind.Unspecified);
    Display("Unspecified: .....", myDt);
    }

// Display the value and Kind property of a DateTime structure, the
// DateTime structure converted to local time, and the DateTime
// structure converted to universal time.

    public static string datePatt = @"M/d/yyyy hh:mm:ss tt";
    public static void Display(string title, DateTime inputDt)
    {
    DateTime dispDt = inputDt;
    string dtString;

// Display the original DateTime.

    dtString = dispDt.ToString(datePatt);
    Console.WriteLine("{0} {1}, Kind = {2}",
                      title, dtString, dispDt.Kind);

// Convert inputDt to local time and display the result.
// If inputDt.Kind is DateTimeKind.Utc, the conversion is performed.
// If inputDt.Kind is DateTimeKind.Local, the conversion is not performed.
// If inputDt.Kind is DateTimeKind.Unspecified, the conversion is
// performed as if inputDt was universal time.

    dispDt = inputDt.ToLocalTime();
    dtString = dispDt.ToString(datePatt);
    Console.WriteLine("  ToLocalTime:     {0}, Kind = {1}",
                      dtString, dispDt.Kind);

// Convert inputDt to universal time and display the result.
// If inputDt.Kind is DateTimeKind.Utc, the conversion is not performed.
// If inputDt.Kind is DateTimeKind.Local, the conversion is performed.
// If inputDt.Kind is DateTimeKind.Unspecified, the conversion is
// performed as if inputDt was local time.

    dispDt = inputDt.ToUniversalTime();
    dtString = dispDt.ToString(datePatt);
    Console.WriteLine("  ToUniversalTime: {0}, Kind = {1}",
                      dtString, dispDt.Kind);
    Console.WriteLine();
    }

// Display the value and Kind property for DateTime.Now and DateTime.UtcNow.

    public static void DisplayNow(string title, DateTime inputDt)
    {
    string dtString = inputDt.ToString(datePatt);
    Console.WriteLine("{0} {1}, Kind = {2}",
                      title, dtString, inputDt.Kind);
    }
}

/*
This code example produces the following results:

UtcNow: .......... 5/6/2005 09:34:42 PM, Kind = Utc
Now: ............. 5/6/2005 02:34:42 PM, Kind = Local

Utc: ............. 5/6/2005 02:34:42 PM, Kind = Utc
  ToLocalTime:     5/6/2005 07:34:42 AM, Kind = Local
  ToUniversalTime: 5/6/2005 02:34:42 PM, Kind = Utc

Local: ........... 5/6/2005 02:34:42 PM, Kind = Local
  ToLocalTime:     5/6/2005 02:34:42 PM, Kind = Local
  ToUniversalTime: 5/6/2005 09:34:42 PM, Kind = Utc

Unspecified: ..... 5/6/2005 02:34:42 PM, Kind = Unspecified
  ToLocalTime:     5/6/2005 07:34:42 AM, Kind = Local
  ToUniversalTime: 5/6/2005 09:34:42 PM, Kind = Utc

*/

' This code example demonstrates the DateTime Kind, Now, and
' UtcNow properties, and the SpecifyKind(), ToLocalTime(), 
' and ToUniversalTime() methods.
Class Sample
    Public Shared Sub Main() 
        ' Get the date and time for the current moment, adjusted 
        ' to the local time zone.
        Dim saveNow As DateTime = DateTime.Now
        
        ' Get the date and time for the current moment expressed 
        ' as coordinated universal time (UTC).
        Dim saveUtcNow As DateTime = DateTime.UtcNow
        Dim myDt As DateTime
        
        ' Display the value and Kind property of the current moment 
        ' expressed as UTC and local time.
        DisplayNow("UtcNow: ..........", saveUtcNow)
        DisplayNow("Now: .............", saveNow)
        Console.WriteLine()
        
        ' Change the Kind property of the current moment to 
        ' DateTimeKind.Utc and display the result.
        myDt = DateTime.SpecifyKind(saveNow, DateTimeKind.Utc)
        Display("Utc: .............", myDt)
        
        ' Change the Kind property of the current moment to 
        ' DateTimeKind.Local and display the result.
        myDt = DateTime.SpecifyKind(saveNow, DateTimeKind.Local)
        Display("Local: ...........", myDt)
        
        ' Change the Kind property of the current moment to 
        ' DateTimeKind.Unspecified and display the result.
        myDt = DateTime.SpecifyKind(saveNow, DateTimeKind.Unspecified)
        Display("Unspecified: .....", myDt)
    End Sub
    
    ' Display the value and Kind property of a DateTime structure, the 
    ' DateTime structure converted to local time, and the DateTime 
    ' structure converted to universal time. 

    Public Shared datePatt As String = "M/d/yyyy hh:mm:ss tt"
    
    Public Shared Sub Display(ByVal title As String, ByVal inputDt As DateTime) 
        Dim dispDt As DateTime = inputDt
        Dim dtString As String
        
        ' Display the original DateTime.
        dtString = dispDt.ToString(datePatt)
        Console.WriteLine("{0} {1}, Kind = {2}", title, dtString, dispDt.Kind)
        
        ' Convert inputDt to local time and display the result. 
        ' If inputDt.Kind is DateTimeKind.Utc, the conversion is performed.
        ' If inputDt.Kind is DateTimeKind.Local, the conversion is not performed.
        ' If inputDt.Kind is DateTimeKind.Unspecified, the conversion is 
        ' performed as if inputDt was universal time.
        dispDt = inputDt.ToLocalTime()
        dtString = dispDt.ToString(datePatt)
        Console.WriteLine("  ToLocalTime:     {0}, Kind = {1}", dtString, dispDt.Kind)
        
        ' Convert inputDt to universal time and display the result. 
        ' If inputDt.Kind is DateTimeKind.Utc, the conversion is not performed.
        ' If inputDt.Kind is DateTimeKind.Local, the conversion is performed.
        ' If inputDt.Kind is DateTimeKind.Unspecified, the conversion is 
        ' performed as if inputDt was local time.
        dispDt = inputDt.ToUniversalTime()
        dtString = dispDt.ToString(datePatt)
        Console.WriteLine("  ToUniversalTime: {0}, Kind = {1}", dtString, dispDt.Kind)
        Console.WriteLine()
    End Sub
    
    
    ' Display the value and Kind property for DateTime.Now and DateTime.UtcNow.

    Public Shared Sub DisplayNow(ByVal title As String, ByVal inputDt As DateTime) 
        Dim dtString As String = inputDt.ToString(datePatt)
        Console.WriteLine("{0} {1}, Kind = {2}", title, dtString, inputDt.Kind)
    End Sub
End Class

'
'This code example produces the following results:
'
'UtcNow: .......... 5/6/2005 09:34:42 PM, Kind = Utc
'Now: ............. 5/6/2005 02:34:42 PM, Kind = Local
'
'Utc: ............. 5/6/2005 02:34:42 PM, Kind = Utc
'  ToLocalTime:     5/6/2005 07:34:42 AM, Kind = Local
'  ToUniversalTime: 5/6/2005 02:34:42 PM, Kind = Utc
'
'Local: ........... 5/6/2005 02:34:42 PM, Kind = Local
'  ToLocalTime:     5/6/2005 02:34:42 PM, Kind = Local
'  ToUniversalTime: 5/6/2005 09:34:42 PM, Kind = Utc
'
'Unspecified: ..... 5/6/2005 02:34:42 PM, Kind = Unspecified
'  ToLocalTime:     5/6/2005 07:34:42 AM, Kind = Local
'  ToUniversalTime: 5/6/2005 09:34:42 PM, Kind = Utc
'

注解

对象 DateTime 由 Kind 字段组成,该字段指示时间值是否基于本地时间、协调世界时 (UTC) ,以及包含以 100 纳米秒刻度度量的时间值的刻度字段。 该方法SpecifyKind使用指定的kind参数和原始时间值创建新DateTime对象。

重要

返回 DateTime 的值不表示与参数相同的即时时间 value ,并且 SpecifyKind 不是时区转换方法。 相反,它会保留参数指定的 value 时间不变,并将属性设置为 Kind kind。 有关时区转换的信息,请参阅“在时区 之间转换时间”。

此方法 SpecifyKind 在具有未指定 Kind 字段的对象接收 DateTime 对象的互操作性方案中非常有用,但可以通过独立方式确定 Ticks 字段表示本地时间或 UTC。

适用于

另请参阅