File.GetLastAccessTime 方法
返回上次访问指定文件或目录的日期和时间。
**命名空间:**System.IO
**程序集:**mscorlib(在 mscorlib.dll 中)
语法
声明
Public Shared Function GetLastAccessTime ( _
path As String _
) As DateTime
用法
Dim path As String
Dim returnValue As DateTime
returnValue = File.GetLastAccessTime(path)
public static DateTime GetLastAccessTime (
string path
)
public:
static DateTime GetLastAccessTime (
String^ path
)
public static DateTime GetLastAccessTime (
String path
)
public static function GetLastAccessTime (
path : String
) : DateTime
参数
- path
要获取其访问日期和时间信息的文件或目录。
返回值
一个 DateTime 结构,它被设置为上次访问指定文件或目录的日期和时间。该值用本地时间表示。
异常
异常类型 | 条件 |
---|---|
调用方没有所要求的权限。 |
|
path 是一个零长度字符串,仅包含空白或者包含一个或多个由 InvalidPathChars 定义的无效字符。 |
|
path 为 空引用(在 Visual Basic 中为 Nothing)。 |
|
指定的路径、文件名或者两者都超出了系统定义的最大长度。例如,在基于 Windows 的平台上,路径必须小于 248 个字符,文件名必须小于 260 个字符。 |
|
未找到指定的路径。 |
|
path 的格式无效。 |
备注
允许 path 参数指定相对或绝对路径信息。相对路径信息被解释为相对于当前工作目录。若要获取当前工作目录,请参见 GetCurrentDirectory。
有关使用此方法的示例,请参见“示例”部分。下表列出了其他典型或相关的 I/O 任务的示例。
若要执行此操作... |
请参见本主题中的示例... |
---|---|
写入文本文件。 |
|
读取文本文件。 |
|
向文件中追加文本。 |
|
重命名或移动文件。 |
示例
下面的示例说明 GetLastAccessTime。
Imports System
Imports System.IO
Imports System.Text
Public Class Test
Public Shared Sub Main()
Try
Dim path As String = "c:\Temp\MyTest.txt"
If File.Exists(path) = False Then
File.Create(path)
End If
File.SetLastAccessTime(path, New DateTime(1985, 5, 4))
' Get the creation time of a well-known directory.
Dim dt As DateTime = File.GetLastAccessTime(path)
Console.WriteLine("The last access time for this file was {0}.", dt)
' Update the last access time.
File.SetLastAccessTime(path, DateTime.Now)
dt = File.GetLastAccessTime(path)
Console.WriteLine("The last access time for this file was {0}.", dt)
Catch e As Exception
Console.WriteLine("The process failed: {0}", e.ToString())
End Try
End Sub
End Class
using System;
using System.IO;
class Test
{
public static void Main()
{
try
{
string path = @"c:\Temp\MyTest.txt";
if (!File.Exists(path))
{
File.Create(path);
}
File.SetLastAccessTime(path, new DateTime(1985,5,4));
// Get the creation time of a well-known directory.
DateTime dt = File.GetLastAccessTime(path);
Console.WriteLine("The last access time for this file was {0}.", dt);
// Update the last access time.
File.SetLastAccessTime(path, DateTime.Now);
dt = File.GetLastAccessTime(path);
Console.WriteLine("The last access time for this file was {0}.", dt);
}
catch (Exception e)
{
Console.WriteLine("The process failed: {0}", e.ToString());
}
}
}
using namespace System;
using namespace System::IO;
int main()
{
try
{
String^ path = "c:\\Temp\\MyTest.txt";
if ( !File::Exists( path ) )
{
File::Create( path );
}
File::SetLastAccessTime( path, DateTime(1985,5,4) );
// Get the creation time of a well-known directory.
DateTime dt = File::GetLastAccessTime( path );
Console::WriteLine( "The last access time for this file was {0}.", dt );
// Update the last access time.
File::SetLastAccessTime( path, DateTime::Now );
dt = File::GetLastAccessTime( path );
Console::WriteLine( "The last access time for this file was {0}.", dt );
}
catch ( Exception^ e )
{
Console::WriteLine( "The process failed: {0}", e );
}
}
import System.*;
import System.IO.*;
class Test
{
public static void main(String[] args)
{
try {
String path = "c:\\Temp\\MyTest.txt";
if (!(File.Exists(path))) {
File.Create(path);
}
File.SetLastAccessTime(path, new DateTime(1985, 5, 4));
// Get the creation time of a well-known directory.
DateTime dt = File.GetLastAccessTime(path);
Console.WriteLine("The last access time for this file was {0}.",
dt);
// Update the last access time.
File.SetLastAccessTime(path, DateTime.get_Now());
dt = File.GetLastAccessTime(path);
Console.WriteLine("The last access time for this file was {0}.",
dt);
}
catch (System.Exception e) {
Console.WriteLine("The process failed: {0}", e.ToString());
}
} //main
} //Test
.NET Framework 安全性
- FileIOPermission 用于读取指定的文件。关联的枚举:FileIOPermissionAccess.Read
平台
Windows 98、Windows 2000 SP4、Windows CE、Windows Millennium Edition、Windows Mobile for Pocket PC、Windows Mobile for Smartphone、Windows Server 2003、Windows XP Media Center Edition、Windows XP Professional x64 Edition、Windows XP SP2、Windows XP Starter Edition
.NET Framework 并不是对每个平台的所有版本都提供支持。有关受支持版本的列表,请参见系统要求。
版本信息
.NET Framework
受以下版本支持:2.0、1.1、1.0
.NET Compact Framework
受以下版本支持:2.0、1.0