FileInfo(String) 构造函数

参考

定义

命名空间:: System.IO

程序集:: mscorlib.dll, System.IO.FileSystem.dll

程序集:: System.IO.FileSystem.dll

程序集:: System.Runtime.dll

程序集:: mscorlib.dll

程序集:: netstandard.dll

Source:: FileInfo.cs

Source:: FileInfo.cs

Source:: FileInfo.cs

重要

一些信息与预发行产品相关，相应产品在发行之前可能会进行重大修改。对于此处提供的信息，Microsoft 不作任何明示或暗示的担保。

初始化作为文件路径的包装的 FileInfo 类的新实例。

public:
 FileInfo(System::String ^ fileName);

public FileInfo (string fileName);

new System.IO.FileInfo : string -> System.IO.FileInfo

Public Sub New (fileName As String)

参数

fileName: String

新文件的完全限定名或相对文件名。路径不要以目录分隔符结尾。

例外

ArgumentNullException

fileName 为 null。

SecurityException

调用方没有所要求的权限。

ArgumentException

.NET Framework 和 2.1 之前的 .NET Core 版本：文件名为空、仅包含空格或包含无效字符。

UnauthorizedAccessException

拒绝访问 fileName。

PathTooLongException

指定的路径和/或文件名超过了系统定义的最大长度。

NotSupportedException

fileName 在字符串中间包含一个冒号 (:)。

示例

以下示例使用此构造函数创建两个文件，然后写入、读取、复制和删除。

using namespace System;
using namespace System::IO;

int main()
{
   String^ path = "c:\\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 );
   }
}

//This code produces output similar to the following; 
//results may vary based on the computer/file structure/etc.:
//
//Hello
//And
//Welcome
//c:\MyTest.txt was copied to c:\MyTest.txttemp.
//c:\MyTest.txttemp was successfully deleted.

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());
        }
    }
}
//This code produces output similar to the following;
//results may vary based on the computer/file structure/etc.:
//
//Hello
//And
//Welcome
//c:\MyTest.txt was copied to c:\MyTest.txttemp.
//c:\MyTest.txttemp was successfully deleted.

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
'This code produces output similar to the following; 
'results may vary based on the computer/file structure/etc.:
'
'Hello
'And
'Welcome
'c:\MyTest.txt was copied to c:\MyTest.txttemp.
'c:\MyTest.txttemp was successfully deleted.

以下示例打开现有文件或创建文件，将文本追加到该文件，并显示结果。

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() );
}
//This code produces output similar to the following; 
//results may vary based on the computer/file structure/etc.:
//
//This is a new entry to add to the file
//This is yet another line to add...

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() );
    }
}
//This code produces output similar to the following;
//results may vary based on the computer/file structure/etc.:
//
//Add as many lines as you like...
//Add another line to the output...
//This is a new entry to add to the file
//This is yet another line to add...

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
End Class
'This code produces output similar to the following; 
'results may vary based on the computer/file structure/etc.:
'
'This is a new entry to add to the file
'This is yet another line to add...

注解

可以指定完全限定或相对文件名，但安全检查获取完全限定的名称。

适用于

产品	版本
.NET	Core 1.0, Core 1.1, Core 2.0, Core 2.1, Core 2.2, Core 3.0, Core 3.1, 5, 6, 7, 8, 9
.NET Framework	1.1, 2.0, 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1
.NET Standard	1.3, 1.4, 1.6, 2.0, 2.1
UWP	10.0

通过

FileInfo(String) 构造函数

定义

参数

例外

示例

注解

适用于

另请参阅

其他资源