FileSystemInfo.LastAccessTime Property

Definition

取得或設定上次存取目前檔案或目錄的時間。Gets or sets the time the current file or directory was last accessed.

public:
 property DateTime LastAccessTime { DateTime get(); void set(DateTime value); };
public DateTime LastAccessTime { get; set; }
member this.LastAccessTime : DateTime with get, set
Public Property LastAccessTime As DateTime

Property Value

DateTime

上次存取目前檔案或目錄的時間。The time that the current file or directory was last accessed.

Exceptions

Refresh() 無法初始化資料。Refresh() cannot initialize the data.

目前的作業系統不是 Windows NT 或更新版本。The current operating system is not Windows NT or later.

呼叫端嘗試設定無效的存取時間The caller attempts to set an invalid access time

Examples

下列程式碼範例將示範如何透過「觸控」作業來更新 LastAccessTime 屬性。The following code example demonstrates the updating of the LastAccessTime property through a "touch" operation. 在此範例中,會「觸及」檔案,將 CreationTimeLastAccessTimeLastWriteTime 屬性更新為目前的日期和時間。In this example, the file is "touched", updating the CreationTime, LastAccessTime and LastWriteTime properties to the current date and time.

using System;
using System.IO;

namespace touch
{
    class Touch
    {
        static void Main(string[] args)
        {
            // Make sure a filename was provided.
            if (args.Length > 0)
            {
                // Verify that the provided filename exists.
                if (File.Exists(args[0]))
                {
                    FileInfo fi = new FileInfo(args[0]);
                    touchFile(fi);
                }
                else
                {
                    Console.WriteLine(
                        "Could not find the file: {0}.", args[0]);
                }
            }
            else
            {
                Console.WriteLine("No file was specified.");
            }
        }

        static void touchFile(FileSystemInfo fsi)
        {
            Console.WriteLine("Touching: {0}", fsi.FullName);

            // Update the CreationTime, LastWriteTime and LastAccessTime.
            try
            {
                fsi.CreationTime = fsi.LastWriteTime = fsi.LastAccessTime =
                    DateTime.Now;
            }
            catch (Exception e)
            {
                Console.WriteLine("Error: {0}", e.Message);
            }
        }
    }
}
Imports System.IO

Public Class Touch
    Public Shared Sub Main(ByVal args() As String)

        ' Make sure an argument (filename) was provided.
        If args.Length > 0 Then

            ' Verify that the provided filename exists.
            If File.Exists(args(0)) Then
                Dim fi As FileInfo = New FileInfo(args(0))
                touchFile(fi)
            Else
                Console.WriteLine("Could not find the file {0}", args(0))
            End If
        Else
            Console.WriteLine("No file specified.")
        End If
    End Sub

    Public Shared Sub touchFile(ByVal fsi As FileSystemInfo)
        Console.WriteLine("Touching: {0}", fsi.FullName)

        ' Update the CreationTime, LastWriteTime and LastAccessTime.
        Try
            fsi.CreationTime = DateTime.Now
            fsi.LastAccessTime = DateTime.Now
            fsi.LastWriteTime = DateTime.Now
        Catch e As Exception
            Console.WriteLine("Error: {0}", e.Message)
        End Try

    End Sub

End Class

Remarks

Note

這個方法可能會傳回不正確的值,因為它會使用原生函式,其值可能不會由作業系統持續更新。This method may return an inaccurate value because it uses native functions whose values may not be continuously updated by the operating system.

如果 FileSystemInfo 物件中所描述的檔案不存在,此屬性會傳回12:00 年1月 1601 1 日午夜If the file described in the FileSystemInfo object does not exist, this property returns 12:00 midnight, January 1, 1601 A.D. 西元國際標準時間(UTC),調整為當地時間。(C.E.) Coordinated Universal Time (UTC), adjusted to local time.

如果 FileSystemInfo 物件的目前實例是從下列任何一種 DirectoryInfo 方法傳回,則會預先快取 LastAccessTimeUtc 屬性的值:The value of the LastAccessTimeUtc property is pre-cached if the current instance of the FileSystemInfo object was returned from any of the following DirectoryInfo methods:

若要取得最新的值,請呼叫 Refresh 方法。To get the latest value, call the Refresh method.

Applies to

See also