Directory.GetLastWriteTime(String) 方法

定义

命名空间:
System.IO
程序集:
mscorlib.dll, System.IO.FileSystem.dll
程序集:
mscorlib.dll
程序集:
System.IO.FileSystem.dll
程序集:
netstandard.dll

返回上次写入指定文件或目录的日期和时间。

public:
 static DateTime GetLastWriteTime(System::String ^ path);
public static DateTime GetLastWriteTime(string path);
static member GetLastWriteTime : string -> DateTime
Public Shared Function GetLastWriteTime (path As String) As DateTime

参数

path
String

要获取修改日期和时间信息的文件或目录。

返回

DateTime

设置为指定文件或目录上次写入的日期和时间的结构。 此值以本地时间表示。

例外

UnauthorizedAccessException

调用方没有所需的权限。

ArgumentException

低于 2.1 的 .NET Framework 和 .NET Core 版本： path 是长度为零的字符串，仅包含空格，或包含一个或多个无效字符。 可以使用该方法查询无效字符 GetInvalidPathChars() 。

ArgumentNullException

path 是 null。

PathTooLongException

指定的路径、文件名或两者都超过了系统定义的最大长度。

示例

以下示例演示如何使用 GetLastWriteTime。

using System;
using System.IO;

class Test
{
    public static void Main()
    {
        try
        {
            string path = @"c:\MyDir";
            if (!Directory.Exists(path))
            {
                Directory.CreateDirectory(path);
            }
            else
            {
                // Take an action which will affect the write time.
                Directory.SetLastWriteTime(path, new DateTime(1985,4,3));
            }

            // Get the creation time of a well-known directory.
            DateTime dt = Directory.GetLastWriteTime(path);
            Console.WriteLine("The last write time for this directory was {0}", dt);
            
            // Update the last write time.
            Directory.SetLastWriteTime(path, DateTime.Now);
            dt = Directory.GetLastWriteTime(path);
            Console.WriteLine("The last write time for this directory was {0}", dt);
        }

        catch (Exception e)
        {
            Console.WriteLine("The process failed: {0}", e.ToString());
        }
    }
}

open System
open System.IO

try
    let path = @"c:\MyDir"
    if not (Directory.Exists path) then
        Directory.CreateDirectory path |> ignore
    else
        // Take an action which will affect the write time.
        Directory.SetLastWriteTime(path, DateTime(1985, 4, 3))

    // Get the creation time of a well-known directory.
    let dt = Directory.GetLastWriteTime path
    printfn $"The last write time for this directory was {dt}"
    
    // Update the last write time.
    Directory.SetLastWriteTime(path, DateTime.Now)
    let dt = Directory.GetLastWriteTime path
    printfn $"The last write time for this directory was {dt}"

with e ->
    printfn $"The process failed: {e}"

Imports System.IO

Public Class Test
    Public Shared Sub Main()
        Try
            Dim path As String = "c:\MyDir"
            If Directory.Exists(path) = False Then
                Directory.CreateDirectory(path)
            Else
                ' Take an action which will affect the write time.
                Directory.SetLastWriteTime(path, New DateTime(1985, 4, 3))
            End If

            ' Get the creation time of a well-known directory.
            Dim dt As DateTime = Directory.GetLastWriteTime(path)
            Console.WriteLine("The last write time for this directory was {0}", dt)

            ' Update the last write time.
            Directory.SetLastWriteTime(path, DateTime.Now)
            dt = Directory.GetLastWriteTime(path)
            Console.WriteLine("The last write time for this directory was {0}", dt)

        Catch e As Exception
            Console.WriteLine("The process failed: {0}", e.ToString())
        End Try
    End Sub
End Class

注解

注释

此方法可能会返回不准确的值，因为它使用本机函数，其值可能不会由操作系统持续更新。

如果参数中描述的 path 目录不存在，此方法返回 1601 年 1 月 1 日午夜 12：00（C.E.）协调世界时（UTC），调整为当地时间。

允许参数 path 指定相对路径或绝对路径信息。 相对路径信息解释为相对于当前工作目录。 若要获取当前工作目录，请参阅 GetCurrentDirectory。

参数的 path 区分大小写对应于运行代码的文件系统。 例如，它在 NTFS（默认 Windows 文件系统）上不区分大小写，在 Linux 文件系统上区分大小写。

有关常见 I/O 任务的列表，请参阅 常见 I/O 任务。

适用于

另请参阅