FileWebRequest.BeginGetRequestStream(AsyncCallback, Object) Metoda

Reference

Definice

Obor názvů:: System.Net

Sestavení:: System.Net.Requests.dll

Sestavení:: System.dll

Sestavení:: netstandard.dll

Zdroj:: FileWebRequest.cs

Zdroj:: FileWebRequest.cs

Zdroj:: FileWebRequest.cs

Důležité

Některé informace platí pro předběžně vydaný produkt, který se může zásadně změnit, než ho výrobce nebo autor vydá. Microsoft neposkytuje žádné záruky, výslovné ani předpokládané, týkající se zde uváděných informací.

Zahájí asynchronní požadavek na objekt, který Stream se má použít k zápisu dat.

public:
 override IAsyncResult ^ BeginGetRequestStream(AsyncCallback ^ callback, System::Object ^ state);

public override IAsyncResult BeginGetRequestStream (AsyncCallback? callback, object? state);

public override IAsyncResult BeginGetRequestStream (AsyncCallback callback, object state);

override this.BeginGetRequestStream : AsyncCallback * obj -> IAsyncResult

Public Overrides Function BeginGetRequestStream (callback As AsyncCallback, state As Object) As IAsyncResult

Parametry

callback: AsyncCallback

Delegát.AsyncCallback

state: Object

Objekt, který obsahuje informace o stavu tohoto požadavku.

Návraty

IAsyncResult

Odkaz IAsyncResult na asynchronní požadavek.

Výjimky

ProtocolViolationException

Vlastnost Method je GET a aplikace zapisuje do datového proudu.

InvalidOperationException

Datový proud se používá předchozím voláním BeginGetRequestStream(AsyncCallback, Object).

ApplicationException

Není k dispozici žádný datový proud zápisu.

WebException

Byla FileWebRequest přerušena.

Příklady

Následující příklad kódu používá BeginGetRequestStream k vytvoření asynchronního požadavku na Stream objekt.

public ref class RequestDeclare
{
public:
   FileWebRequest^ myFileWebRequest;
   String^ userinput;
   RequestDeclare()
   {
      myFileWebRequest = nullptr;
   }

};

ref class FileWebRequest_reqbeginend
{
public:
   static ManualResetEvent^ allDone = gcnew ManualResetEvent( false );
   static void ReadCallback( IAsyncResult^ ar )
   {
      try
      {
         
         // State of the request is asynchronous.
         RequestDeclare^ requestDeclare = dynamic_cast<RequestDeclare^>(ar->AsyncState);
         FileWebRequest^ myFileWebRequest = requestDeclare->myFileWebRequest;
         String^ sendToFile = requestDeclare->userinput;
         
         // End the Asynchronus request by calling the 'EndGetRequestStream()' method.
         Stream^ readStream = myFileWebRequest->EndGetRequestStream( ar );
         
         // Convert the String* into Byte array.
         ASCIIEncoding^ encoder = gcnew ASCIIEncoding;
         array<Byte>^byteArray = encoder->GetBytes( sendToFile );
         
         // Write to the stream.
         readStream->Write( byteArray, 0, sendToFile->Length );
         readStream->Close();
         allDone->Set();
         Console::WriteLine( "\nThe String you entered was successfully written into the file." );
         Console::WriteLine( "\nPress Enter to continue." );
      }
      catch ( ApplicationException^ e ) 
      {
         Console::WriteLine( "ApplicationException is : {0}", e->Message );
      }

   }

};

int main()
{
   array<String^>^args = Environment::GetCommandLineArgs();
   if ( args->Length < 2 )
   {
      Console::WriteLine( "\nPlease enter the file name as command line parameter:" );
      Console::WriteLine( "Usage:FileWebRequest_reqbeginend <systemname>/<sharedfoldername>/<filename>\n" );
      Console::WriteLine( "Example:FileWebRequest_reqbeginend shafeeque/shaf/hello.txt" );
   }
   else
   {
      try
      {
         
         // Place a webrequest.
         WebRequest^ myWebRequest = WebRequest::Create( String::Concat( "file://", args[ 1 ] ) );
         
         // Create an instance of the 'RequestDeclare' and associate the 'myWebRequest' to it.
         RequestDeclare^ requestDeclare = gcnew RequestDeclare;
         requestDeclare->myFileWebRequest = dynamic_cast<FileWebRequest^>(myWebRequest);
         
         // Set the 'Method' property of 'FileWebRequest' Object* to 'POST' method.
         requestDeclare->myFileWebRequest->Method = "POST";
         Console::WriteLine( "Enter the String* you want to write into the file:" );
         requestDeclare->userinput = Console::ReadLine();
         
         // Begin the Asynchronous request for getting file content using 'BeginGetRequestStream()' method .
         IAsyncResult^ r = dynamic_cast<IAsyncResult^>(requestDeclare->myFileWebRequest->BeginGetRequestStream( gcnew AsyncCallback( &FileWebRequest_reqbeginend::ReadCallback ), requestDeclare ));
         FileWebRequest_reqbeginend::allDone->WaitOne();
         Console::Read();
      }
      catch ( ProtocolViolationException^ e ) 
      {
         Console::WriteLine( "ProtocolViolationException is : {0}", e->Message );
      }
      catch ( InvalidOperationException^ e ) 
      {
         Console::WriteLine( "InvalidOperationException is : {0}", e->Message );
      }
      catch ( UriFormatException^ e ) 
      {
         Console::WriteLine( "UriFormatExceptionException is : {0}", e->Message );
      }

   }
}


public class RequestDeclare
{
     public FileWebRequest myFileWebRequest;	
     public String userinput;

    public RequestDeclare()
    {
        myFileWebRequest = null;
    }
}

class FileWebRequest_reqbeginend
{
    public static ManualResetEvent allDone = new ManualResetEvent(false);

    static void Main(string[] args)
    {
      if (args.Length < 1)
      {
        Console.WriteLine("\nPlease enter the file name as command line parameter:");
           Console.WriteLine("Usage:FileWebRequest_reqbeginend <systemname>/<sharedfoldername>/<filename>\nExample:FileWebRequest_reqbeginend shafeeque/shaf/hello.txt");
      }
      else
      {

        try
         {

              // Place a webrequest.
              WebRequest myWebRequest= WebRequest.Create("file://"+args[0]);
        
              // Create an instance of the 'RequestDeclare' and associate the 'myWebRequest' to it.		
              RequestDeclare requestDeclare = new RequestDeclare();
              requestDeclare.myFileWebRequest = (FileWebRequest)myWebRequest;
              // Set the 'Method' property of 'FileWebRequest' object to 'POST' method.
              requestDeclare.myFileWebRequest.Method="POST";
              Console.WriteLine("Enter the string you want to write into the file:");
              requestDeclare.userinput = Console.ReadLine();

              // Begin the Asynchronous request for getting file content using 'BeginGetRequestStream()' method .
              IAsyncResult r=(IAsyncResult) requestDeclare.myFileWebRequest.BeginGetRequestStream(new AsyncCallback(ReadCallback),requestDeclare);			
              allDone.WaitOne();

              Console.Read();
        }
        catch(ProtocolViolationException e)
        {
              Console.WriteLine("ProtocolViolationException is :"+e.Message);
        }
        catch(InvalidOperationException e)
        {
            Console.WriteLine("InvalidOperationException is :"+e.Message);
        }
        catch(UriFormatException e)
        {
            Console.WriteLine("UriFormatExceptionException is :"+e.Message);
         }
     }
    }

    private static void ReadCallback(IAsyncResult ar)
    {	

     try
  {

          // State of the request is asynchronous.
          RequestDeclare requestDeclare=(RequestDeclare) ar.AsyncState;
          FileWebRequest myFileWebRequest=requestDeclare.myFileWebRequest;
          String sendToFile = requestDeclare.userinput;

          // End the Asynchronus request by calling the 'EndGetRequestStream()' method.
          Stream readStream=myFileWebRequest.EndGetRequestStream(ar);
                    
          // Convert the string into byte array.
            
          ASCIIEncoding encoder = new ASCIIEncoding();
          byte[] byteArray = encoder.GetBytes(sendToFile);
        
          // Write to the stream.
          readStream.Write(byteArray,0,sendToFile.Length);
          readStream.Close();
          allDone.Set();
            
          Console.WriteLine("\nThe String you entered was successfully written into the file.");
      Console.WriteLine("\nPress Enter to continue.");	
     }
    catch(ApplicationException e)
      {
          Console.WriteLine("ApplicationException is :"+e.Message);
      }				
    }

Public Class RequestDeclare
    Public myFileWebRequest As FileWebRequest
    Public userinput As [String]
    
    
    Public Sub New()
        myFileWebRequest = Nothing
    End Sub
End Class


Class FileWebRequest_reqbeginend
    Public Shared allDone As New ManualResetEvent(False)
    
    ' Entry point which delegates to C-style main Private Function.
    Public Overloads Shared Sub Main()
        Main(System.Environment.GetCommandLineArgs())
    End Sub
    
    
    Overloads Shared Sub Main(args() As String)
        If args.Length < 2 Then
            Console.WriteLine(ControlChars.Cr + "Please enter the file name as command line parameter:")
            Console.WriteLine("Usage:FileWebRequest_reqbeginend <systemname>/<sharedfoldername>/<filename>")
        Console.WriteLine("Example: FileWebRequest_reqbeginend shafeeque/shaf/hello.txt")
        
        Else
            Try

                ' Place a webrequest.
                Dim myWebRequest As WebRequest = WebRequest.Create(("file://" + args(1)))
                
                ' Create an instance of the 'RequestDeclare' and associate the 'myWebRequest' to it.		
                Dim requestDeclare As New RequestDeclare()
                requestDeclare.myFileWebRequest = CType(myWebRequest, FileWebRequest)
                ' Set the 'Method' property of 'FileWebRequest' object to 'POST' method.
                requestDeclare.myFileWebRequest.Method = "POST"
                Console.WriteLine("Enter the string you want to write into the file:")
                requestDeclare.userinput = Console.ReadLine()
                
                ' Begin the Asynchronous request for getting file content using 'BeginGetRequestStream()' method .
                Dim r As IAsyncResult = CType(requestDeclare.myFileWebRequest.BeginGetRequestStream(AddressOf ReadCallback, requestDeclare), IAsyncResult)
                allDone.WaitOne()
                
                Console.Read()
            Catch e As ProtocolViolationException
                Console.WriteLine(("ProtocolViolationException is :" + e.Message))
            Catch e As InvalidOperationException
                Console.WriteLine(("InvalidOperationException is :" + e.Message))
            Catch e As UriFormatException
                Console.WriteLine(("UriFormatExceptionException is :" + e.Message))
            End Try

        End If 
    End Sub
    
    
    Private Shared Sub ReadCallback(ar As IAsyncResult)
        Try

            ' State of the request is asynchronous.
            Dim requestDeclare As RequestDeclare = CType(ar.AsyncState, RequestDeclare)
            Dim myFileWebRequest As FileWebRequest = requestDeclare.myFileWebRequest
            Dim sendToFile As [String] = requestDeclare.userinput
            
            ' End the Asynchronus request by calling the 'EndGetRequestStream()' method.
            Dim readStream As Stream = myFileWebRequest.EndGetRequestStream(ar)
            
            ' Convert the string into byte array.
            Dim encoder As New ASCIIEncoding()
            Dim byteArray As Byte() = encoder.GetBytes(sendToFile)
            
            ' Write to the stream.
            readStream.Write(byteArray, 0, sendToFile.Length)
            readStream.Close()
            allDone.Set()

            
            Console.WriteLine(ControlChars.Cr +"The String you entered was successfully written into the file.")
            Console.WriteLine(ControlChars.Cr +"Press Enter to continue.")

            Catch e As ApplicationException
            Console.WriteLine(("ApplicationException is :" + e.Message))
        End Try

    End Sub

Poznámky

Metoda BeginGetRequestStream spustí asynchronní požadavek na datový proud, který se používá k odesílání dat do prostředku systému souborů. Metoda zpětného AsyncCallback volání, která implementuje delegáta, používá metodu EndGetRequestStream k vrácení streamu požadavku.

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