通过

FileInfo 构造函数

  • 项目

初始化 FileInfo 类的新实例，它作为文件路径的包装。

**命名空间:**System.IO
**程序集:**mscorlib（在 mscorlib.dll 中）

语法

声明
Public Sub New ( _
    fileName As String _
)
用法
Dim fileName As String

Dim instance As New FileInfo(fileName)

public FileInfo (
    string fileName
)

public:
FileInfo (
    String^ fileName
)

public FileInfo (
    String fileName
)

public function FileInfo (
    fileName : String
)

参数

  • fileName
    新文件的完全限定名或相对文件名。

异常

异常类型 条件

ArgumentNullException

fileName 为 空引用（在 Visual Basic 中为 Nothing）。

SecurityException

调用方没有所要求的权限。

ArgumentException

文件名为空，只包含空白，或包含无效字符。

UnauthorizedAccessException

对 fileName 的访问被拒绝。

PathTooLongException

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。

NotSupportedException

fileName 字符串中间有一个冒号 (:)。

备注

可以指定完全限定文件名或相对文件名，但是安全检查获取完全限定名。

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...

创建文本文件。

如何：向文件写入文本

写入文本文件。

如何：向文件写入文本

读取文本文件。

如何：从文件读取文本

向文件中追加文本。

如何：打开并追加到日志文件

File.AppendText

FileInfo.AppendText

重命名或移动文件。

File.Move

FileInfo.MoveTo

删除文件。

File.Delete

FileInfo.Delete

复制文件。

File.Copy

FileInfo.CopyTo

获取文件大小。

FileInfo.Length

获取文件属性。

File.GetAttributes

设置文件属性。

File.SetAttributes

确定文件是否存在。

File.Exists

读取二进制文件。

如何：对新建的数据文件进行读取和写入

写入二进制文件。

如何：对新建的数据文件进行读取和写入

检索文件扩展名。

Path.GetExtension

检索文件的完全限定路径。

Path.GetFullPath

检索路径中的文件名和扩展名。

Path.GetFileName

更改文件扩展名。

Path.ChangeExtension

示例

下面的示例使用此构造函数创建两个文件，并接着对其进行写入、读取、复制和删除操作。

Imports System
Imports System.IO

Class Test

    Public Shared Sub Main()
        Dim path As String = "c:\temp\MyTest.txt"
        Dim fi1 As FileInfo = New FileInfo(path)

        If fi1.Exists = False Then
            'Create a file to write to.
            Dim sw As StreamWriter = fi1.CreateText()
            sw.WriteLine("Hello")
            sw.WriteLine("And")
            sw.WriteLine("Welcome")
            sw.Flush()
            sw.Close()
        End If

        'Open the file to read from.
        Dim sr As StreamReader = fi1.OpenText()

        Do While sr.Peek() >= 0
            Console.WriteLine(sr.ReadLine())
        Loop

        Try
            Dim path2 As String = path + "temp"
            Dim fi2 As FileInfo = New FileInfo(path2)

            'Ensure that the target does not exist.
            fi2.Delete()

            'Copy the file.
            fi1.CopyTo(path2)
            Console.WriteLine("{0} was copied to {1}.", path, path2)

            'Delete the newly created file.
            fi2.Delete()
            Console.WriteLine("{0} was successfully deleted.", path2)

        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() 
    {
        string path = @"c:\temp\MyTest.txt";
        FileInfo fi1 = new FileInfo(path);

        if (!fi1.Exists) 
        {
            //Create a file to write to.
            using (StreamWriter sw = fi1.CreateText()) 
            {
                sw.WriteLine("Hello");
                sw.WriteLine("And");
                sw.WriteLine("Welcome");
            }   
        }

        //Open the file to read from.
        using (StreamReader sr = fi1.OpenText()) 
        {
            string s = "";
            while ((s = sr.ReadLine()) != null) 
            {
                Console.WriteLine(s);
            }
        }

        try 
        {
            string path2 = path + "temp";
            FileInfo fi2 = new FileInfo(path2);

            //Ensure that the target does not exist.
            fi2.Delete();

            //Copy the file.
            fi1.CopyTo(path2);
            Console.WriteLine("{0} was copied to {1}.", path, path2);

            //Delete the newly created file.
            fi2.Delete();
            Console.WriteLine("{0} was successfully deleted.", path2);

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

using namespace System;
using namespace System::IO;

int main()
{
   String^ path = "c:\\temp\\MyTest.txt";
   FileInfo^ fi1 = gcnew FileInfo( path );
   if (  !fi1->Exists )
   {
      //Create a file to write to.
      StreamWriter^ sw = fi1->CreateText();
      try
      {
         sw->WriteLine( "Hello" );
         sw->WriteLine( "And" );
         sw->WriteLine( "Welcome" );
      }
      finally
      {
         if ( sw )
            delete (IDisposable^)sw;
      }
   }

   //Open the file to read from.
   StreamReader^ sr = fi1->OpenText();
   try
   {
      String^ s = "";
      while ( s = sr->ReadLine() )
      {
         Console::WriteLine( s );
      }
   }
   finally
   {
      if ( sr )
         delete (IDisposable^)sr;
   }

   try
   {
      String^ path2 = String::Concat( path, "temp" );
      FileInfo^ fi2 = gcnew FileInfo( path2 );
      
      //Ensure that the target does not exist.
      fi2->Delete();
      
      //Copy the file.
      fi1->CopyTo( path2 );
      Console::WriteLine( "{0} was copied to {1}.", path, path2 );
      
      //Delete the newly created file.
      fi2->Delete();
      Console::WriteLine( "{0} was successfully deleted.", path2 );
   }
   catch ( Exception^ e ) 
   {
      Console::WriteLine( "The process failed: {0}", e );
   }
}

import System.*;
import System.IO.*;

class Test
{
    public static void main(String[] args)
    {
        String path = "c:\\temp\\MyTest.txt";
        FileInfo fi1 = new FileInfo(path);

        if (!(fi1.get_Exists())) {
            //Create a file to write to.
            StreamWriter sw = fi1.CreateText();

            try {
                sw.WriteLine("Hello");
                sw.WriteLine("And");
                sw.WriteLine("Welcome");
            }
            finally {
                sw.Dispose();
            }
        }

        //Open the file to read from.
        StreamReader sr = fi1.OpenText();

        try {
            String s = "";

            while ((s = sr.ReadLine())!= null) {
                Console.WriteLine(s);
            }
        }
        finally {
            sr.Dispose();
        }
        try {
            String path2 = path + "temp";
            FileInfo fi2 = new FileInfo(path2);

            //Ensure that the target does not exist.
            fi2.Delete();

            //Copy the file.
            fi1.CopyTo(path2);
            Console.WriteLine("{0} was copied to {1}.", path, path2);

            //Delete the newly created file.
            fi2.Delete();
            Console.WriteLine("{0} was successfully deleted.", path2);
        }
        catch (System.Exception e) {
            Console.WriteLine("The process failed: {0}", e.ToString());
        }
    } //main
} //Test

下面的示例打开一个现有文件或创建一个文件，将文本追加到此文件并显示结果。

Imports System
Imports System.IO

Public Class FileInfoMainTest

    Public Shared Sub Main()
        ' Open an existing file, or create a new one.
        Dim fi As New FileInfo("temp.txt")
        ' Create a writer, ready to add entries to the file.
        Dim sw As StreamWriter = fi.AppendText()
        sw.WriteLine("This is a new entry to add to the file")
        sw.WriteLine("This is yet another line to add...")
        sw.Flush()
        sw.Close()
        Dim sr As New StreamReader(fi.OpenRead())
        ' Get the information out of the file and display it.
        While sr.Peek() <> -1
            Console.WriteLine(sr.ReadLine())
        End While
    End Sub 'Main
End Class 'FileInfoMainTest

using System;
using System.IO;

public class FileInfoMainTest 
{
    public static void Main() 
    {
        // Open an existing file, or create a new one.
        FileInfo fi = new FileInfo("temp.txt");
        // Create a writer, ready to add entries to the file.
        StreamWriter sw = fi.AppendText();
        sw.WriteLine("This is a new entry to add to the file");
        sw.WriteLine("This is yet another line to add...");
        sw.Flush();
        sw.Close();
        // Get the information out of the file and display it.
        StreamReader sr = new StreamReader( fi.OpenRead() );
        while (sr.Peek() != -1)
            Console.WriteLine( sr.ReadLine() );
    }
}

using namespace System;
using namespace System::IO;
int main()
{
   
   // Open an existing file, or create a new one.
   FileInfo^ fi = gcnew FileInfo( "temp.txt" );
   
   // Create a writer, ready to add entries to the file.
   StreamWriter^ sw = fi->AppendText();
   sw->WriteLine( "This is a new entry to add to the file" );
   sw->WriteLine( "This is yet another line to add..." );
   sw->Flush();
   sw->Close();
   
   // Get the information out of the file and display it.
   StreamReader^ sr = gcnew StreamReader( fi->OpenRead() );
   while ( sr->Peek() != -1 )
      Console::WriteLine( sr->ReadLine() );
}

import System;
import System.IO;

public class FileInfoMainTest {
    public static function Main() : void {

        // Open an existing file, or create a new one.
        var fi : FileInfo = new FileInfo("temp.txt");
        // Create a writer, ready to add entries to the file.
        var sw : StreamWriter = fi.AppendText();
        sw.WriteLine("This is a new entry to add to the file");
        sw.WriteLine("This is yet another line to add...");
        sw.Flush();
        sw.Close();
        // Get the information out of the file and display it.
        var sr : StreamReader = new StreamReader( fi.OpenRead() );
        while (sr.Peek() != -1)
            Console.WriteLine( sr.ReadLine() );
    }
}
FileInfoMainTest.Main();

.NET Framework 安全性

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

请参见

参考

FileInfo 类
FileInfo 成员
System.IO 命名空间

其他资源

文件和流 I/O
如何：从文件读取文本
如何：向文件写入文本