FileWebRequest Classe

Definizione

public ref class FileWebRequest : System::Net::WebRequest, System::Runtime::Serialization::ISerializable

public ref class FileWebRequest : System::Net::WebRequest

public class FileWebRequest : System.Net.WebRequest, System.Runtime.Serialization.ISerializable

[System.Serializable]
public class FileWebRequest : System.Net.WebRequest, System.Runtime.Serialization.ISerializable

public class FileWebRequest : System.Net.WebRequest

type FileWebRequest = class
    inherit WebRequest
    interface ISerializable

[<System.Serializable>]
type FileWebRequest = class
    inherit WebRequest
    interface ISerializable

Public Class FileWebRequest
Inherits WebRequest
Implements ISerializable

Public Class FileWebRequest
Inherits WebRequest

Ereditarietà

Object

MarshalByRefObject

WebRequest

FileWebRequest

Attributi

SerializableAttribute

Implementazioni

ISerializable

Esempio

Nell'esempio di codice seguente viene usata la classe FileWebRequest per accedere a una risorsa del file system.

// This program creates or open a text file in which it stores a string.
// Both file and string are passed by the user.
// Note. In order for this program to work, the folder containing the test file
// must be shared with its permissions set to allow write access.
#using <System.dll>

using namespace System;
using namespace System::IO;
using namespace System::Text;
using namespace System::Net;
ref class TestGetRequestStream
{
private:
   static FileWebRequest^ myFileWebRequest;
   static void showUsage()
   {
      Console::WriteLine( "\nPlease enter file name and timeout :" );
      Console::WriteLine( "Usage: cs_getrequeststream <systemname>/<sharedfoldername>/<filename> timeout" );
      Console::WriteLine( "Example: cs_getrequeststream ndpue/temp/hello.txt 1000" );
      Console::WriteLine( "Small timeout values (for instance 3 or less) cause a timeout exception." );
   }

   static void makeFileRequest( String^ fileName, int timeout )
   {
      try
      {
         
         // Create a Uri object.
         Uri^ myUrl = gcnew Uri( String::Format( "file://{0}", fileName ) );
         
         // Create a FileWebRequest object.
         myFileWebRequest = dynamic_cast<FileWebRequest^>(WebRequest::CreateDefault( myUrl ));
         
         // Set the timeout to the value selected by the user.
         myFileWebRequest->Timeout = timeout;
         
         // Set the Method property to POST
         myFileWebRequest->Method = "POST";
         
      }
      catch ( WebException^ e ) 
      {
         Console::WriteLine( "WebException: {0}", e->Message );
      }
      catch ( UriFormatException^ e ) 
      {
         Console::WriteLine( "UriFormatWebException: {0}", e->Message );
      }

   }

   static void writeToFile()
   {
      try
      {
         
         // Enter the string to write into the file.
         Console::WriteLine( "Enter the string you want to write:" );
         String^ userInput = Console::ReadLine();
         
         // Convert the string to Byte array.
         ASCIIEncoding^ encoder = gcnew ASCIIEncoding;
         array<Byte>^byteArray = encoder->GetBytes( userInput );
         
         // Set the ContentLength property.
         myFileWebRequest->ContentLength = byteArray->Length;
         String^ contentLength = myFileWebRequest->ContentLength.ToString();
         Console::WriteLine( "\nThe content length is {0}.", contentLength );
         
         // Get the file stream handler to write into the file.
         Stream^ readStream = myFileWebRequest->GetRequestStream();
         
         // Write to the file stream.
         // Note. In order for this to work the file must be accessible
         // on the network. This can be accomplished by setting the property
         // sharing of the folder containg the file. The permissions
         // can be set so everyone can modify the file.
         // FileWebRequest::Credentials property cannot be used for this purpose.
         readStream->Write( byteArray, 0, userInput->Length );
         Console::WriteLine( "\nThe String you entered was successfully written into the file." );
         
         readStream->Close();
      }
      catch ( WebException^ e ) 
      {
         Console::WriteLine( "The WebException: {0}", e->Message );
      }
      catch ( UriFormatException^ e ) 
      {
         Console::WriteLine( "The UriFormatWebException: {0}", e->Message );
      }

   }


public:
   static void Main()
   {
      array<String^>^args = Environment::GetCommandLineArgs();
      if ( args->Length < 3 )
            showUsage();
      else
      {
         makeFileRequest( args[ 1 ], Int32::Parse( args[ 2 ] ) );
         writeToFile();
      }
   }

};

int main()
{
   TestGetRequestStream::Main();
}

// This example creates or opens a text file and stores a string in it.
// Both the file and the string are passed by the user.
// Note. For this program to work, the folder containing the test file
// must be shared, with its permissions set to allow write access.
using System.Net;
using System;
using System.IO;
using System.Text;

namespace Mssc.PluggableProtocols.File
{
    class TestGetRequestStream
    {
        private static FileWebRequest myFileWebRequest;

        private static void showUsage ()
        {
            Console.WriteLine ("\nPlease enter file name and timeout :");
            Console.WriteLine ("Usage: cs_getrequeststream <systemname>/<sharedfoldername>/<filename> timeout");
            Console.WriteLine ("Example: cs_getrequeststream ngetrequestrtream() ndpue/temp/hello.txt  1000");
            Console.WriteLine ("Small time-out values (for example, 3 or less) cause a time-out exception.");
        }

        private static void makeFileRequest (string fileName, int timeout)
        {
            try
            {
                // Create a Uri object.
                Uri myUrl = new Uri ("file://" + fileName);

                // Create a FileWebRequest object.
                myFileWebRequest = (FileWebRequest)WebRequest.CreateDefault (myUrl);

                // Set the time-out to the value selected by the user.
                myFileWebRequest.Timeout = timeout;

                // Set the Method property to POST
                myFileWebRequest.Method = "POST";
            }
            catch (WebException e)
            {
                Console.WriteLine ("WebException: " + e.Message);
            }
            catch (UriFormatException e)
            {
                Console.WriteLine ("UriFormatWebException: " + e.Message);
            }
        }

        private static void writeToFile ()
        {
            try
            {
                // Enter the string to write to the file.
                Console.WriteLine ("Enter the string you want to write:");

                string userInput = Console.ReadLine ();

                // Convert the string to a byte array.
                ASCIIEncoding encoder = new ASCIIEncoding ();
                byte[] byteArray = encoder.GetBytes (userInput);

                // Set the ContentLength property.
                myFileWebRequest.ContentLength = byteArray.Length;

                string contentLength = myFileWebRequest.ContentLength.ToString ();

                Console.WriteLine ("\nThe content length is {0}.", contentLength);

                // Get the file stream handler to write to the file.
                Stream readStream = myFileWebRequest.GetRequestStream ();

                // Write to the file stream.
                // Note.  For this to work, the file must be accessible
                // on the network. This can be accomplished by setting the property
                // sharing of the folder containg the file.
                // FileWebRequest.Credentials property cannot be used for this purpose.
                readStream.Write (byteArray, 0, userInput.Length);
                Console.WriteLine ("\nThe String you entered was successfully written to the file.");

                readStream.Close ();
            }
            catch (WebException e)
            {
                Console.WriteLine ("The WebException: " + e.Message);
            }
            catch (UriFormatException e)
            {
                Console.WriteLine ("The UriFormatWebException: " + e.Message);
            }
        }

        public static void Main (String[] args)
        {
            if (args.Length < 2)
            {
                showUsage ();
            }
            else
            {
                makeFileRequest (args[0], int.Parse (args[1]));
                writeToFile ();
            }
        }
    }
}

'
' This example creates or opens a text file and stores a string in it. 
' Both the file and the string are passed by the user.
' Note. For this program to work, the folder containing the test file
' must be shared, with its permissions set to allow write access. 

Imports System.Net
Imports System.IO
Imports System.Text

Namespace Mssc.PluggableProtocols.File

    Module TestGetRequestStream

        Class TestGetRequestStream

            Private Shared myFileWebRequest As FileWebRequest

            ' Show how to use this program.
            Private Shared Sub showUsage()
                Console.WriteLine(ControlChars.Lf + "Please enter file name and timeout :")
                Console.WriteLine("Usage: vb_getrequeststream <systemname>/<sharedfoldername>/<filename> timeout")
                Console.WriteLine("Example: vb_getrequeststream ngetrequestrtream() ndpue/temp/hello.txt  1000")
                Console.WriteLine("Small time-out values (for example, 3 or less) cause a time-out exception.")
            End Sub

            Private Shared Sub makeFileRequest(ByVal fileName As String, ByVal timeout As Integer)
                Try
                    ' Create a Uri object.to access the file requested by the user. 
                    Dim myUrl As New Uri("file://" + fileName)

                    ' Create a FileWebRequest object.for the requeste file.
                    myFileWebRequest = CType(WebRequest.CreateDefault(myUrl), FileWebRequest)

                    ' Set the time-out to the value selected by the user.
                    myFileWebRequest.Timeout = timeout

                    ' Set the Method property to POST  
                    myFileWebRequest.Method = "POST"


                Catch e As WebException
                    Console.WriteLine(("WebException is: " + e.Message))
                Catch e As UriFormatException
                    Console.WriteLine(("UriFormatWebException is: " + e.Message))
                End Try

            End Sub

            Private Shared Sub writeToFile()
                Try
                    ' Enter the string to write to the file.
                    Console.WriteLine("Enter the string you want to write:")
                    Dim userInput As String = Console.ReadLine()

                    ' Convert the string to a byte array.
                    Dim encoder As New ASCIIEncoding
                    Dim byteArray As Byte() = encoder.GetBytes(userInput)

                    ' Set the ContentLength property.
                    myFileWebRequest.ContentLength = byteArray.Length

                    Dim contentLength As String = myFileWebRequest.ContentLength.ToString()

                    Console.WriteLine(ControlChars.Lf + "The content length is {0}.", contentLength)


                    ' Get the file stream handler to write to the file.
                    Dim readStream As Stream = myFileWebRequest.GetRequestStream()

                    ' Write to the stream. 
                    ' Note. For this to work the file must be accessible
                    ' on the network. This can be accomplished by setting the property
                    ' sharing of the folder containg the file.  
                    ' FileWebRequest.Credentials property cannot be used for this purpose.
                    readStream.Write(byteArray, 0, userInput.Length)


                    Console.WriteLine(ControlChars.Lf + "The String you entered was successfully written to the file.")

                    readStream.Close()

                Catch e As WebException
                    Console.WriteLine(("WebException is: " + e.Message))
                Catch e As UriFormatException
                    Console.WriteLine(("UriFormatWebException is: " + e.Message))
                End Try

            End Sub

            Public Shared Sub Main(ByVal args() As String)

                If args.Length < 2 Then
                    showUsage()
                Else
                    makeFileRequest(args(0), Integer.Parse(args(1)))
                    writeToFile()
                End If

            End Sub

        End Class



    End Module

End Namespace

Commenti

La classe FileWebRequest implementa la classe di base WebRequestabstract per gli URI (Uniform Resource Identifier) che usano lo schema file:// per richiedere i file locali.

Non usare il costruttore FileWebRequest. Utilizzare il metodo WebRequest.Create per inizializzare nuove istanze della classe FileWebRequest. Se lo schema URI è file://, il metodo Create restituisce un oggetto FileWebRequest.

Il metodo GetResponse effettua una richiesta sincrona per il file specificato nella proprietà RequestUri e restituisce un oggetto FileWebResponse che contiene la risposta. È possibile effettuare una richiesta asincrona per il file usando i metodi BeginGetResponse e EndGetResponse.

Quando si desidera scrivere dati in un file, il metodo GetRequestStream restituisce un'istanza di Stream in cui scrivere. I metodi BeginGetRequestStream e EndGetRequestStream forniscono l'accesso asincrono al flusso di dati di scrittura.

La classe FileWebRequest si basa sulla classe File per la gestione degli errori e la sicurezza dell'accesso al codice.

Costruttori

Proprietà

Metodi

Implementazioni dell'interfaccia esplicita

Si applica a

Vedi anche

• File