FileSystemInfo.LastAccessTime 属性

定义

获取或设置上次访问当前文件或目录的时间。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

属性值

上次访问当前文件或目录的时间。The time that the current file or directory was last accessed.

异常

Refresh() 不能初始化数据。Refresh() cannot initialize the data.

当前操作系统不是 Windows NT 或更高版本。The current operating system is not Windows NT or later.

调用方试图设置无效的访问时间The caller attempts to set an invalid access time

示例

下面的代码示例演示如何通过 "touch" 操作更新 LastAccessTime 属性。The following code example demonstrates the updating of the LastAccessTime property through a "touch" operation. 在此示例中,文件被 "触摸",将 CreationTimeLastAccessTimeLastWriteTime 属性更新为当前日期和时间。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

注解

备注

此方法可能会返回不正确的值,因为它使用的本机函数的值可能不会持续由操作系统进行更新。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 对象中所述的文件不存在,则此属性返回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. 公元协调世界时(UTC),调整为本地时间。(C.E.) Coordinated Universal Time (UTC), adjusted to local time.

如果 FileSystemInfo 对象的当前实例从以下任意 DirectoryInfo 方法返回,则 LastAccessTimeUtc 属性的值将被预先缓存: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:

若要获取最新值,请调用 Refresh 方法。To get the latest value, call the Refresh method.

适用于

另请参阅