FileInfo(String) Konstruktor

Definice

Obor názvů:

System.IO

Sestavení:

System.Runtime.dll

Zdroj:

FileInfo.cs

Inicializuje novou instanci FileInfo třídy, která funguje jako obálka pro cestu k souboru.

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

public FileInfo (string fileName);

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

Public Sub New (fileName As String)

Parametry

fileName

String

Plně kvalifikovaný název nového souboru nebo relativní název souboru. Neukončujte cestu znakem oddělovače adresáře.

Výjimky

ArgumentNullException

fileName je null.

SecurityException

Volající nemá požadované oprávnění.

ArgumentException

.NET Framework a .NET Core verze starší než 2.1: Název souboru je prázdný, obsahuje pouze prázdné znaky nebo obsahuje neplatné znaky.

UnauthorizedAccessException

Přístup k této službě fileName byl odepřen.

PathTooLongException

Zadaná cesta, název souboru nebo obojí překračují maximální délku definovanou systémem.

NotSupportedException

fileName obsahuje dvojtečku (:) uprostřed řetězce.

Příklady

Následující příklad používá tento konstruktor k vytvoření dvou souborů, které jsou pak zapsány do, přečteny, zkopírovány a odstraněny.

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.

Následující příklad otevře existující soubor nebo vytvoří soubor, připojí k němu text a zobrazí výsledky.

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...

Poznámky

Můžete zadat plně kvalifikovaný nebo relativní název souboru, ale kontrola zabezpečení získá plně kvalifikovaný název.

Viz také

• Vstupně-výstupní operace souborů a Stream
• Postupy: Čtení textu ze souboru
• Postupy: Zápis textu do souboru