WebRequest.BeginGetResponse(AsyncCallback, Object) Yöntem

Tanım

Ad Alanı:

System.Net

Bütünleştirilmiş Kod:

System.Net.Requests.dll

Kaynak:

WebRequest.cs

Alt sınıfta geçersiz kılındığında, İnternet kaynağı için zaman uyumsuz bir istek başlar.

public:
 virtual IAsyncResult ^ BeginGetResponse(AsyncCallback ^ callback, System::Object ^ state);

public virtual IAsyncResult BeginGetResponse (AsyncCallback? callback, object? state);

abstract member BeginGetResponse : AsyncCallback * obj -> IAsyncResult
override this.BeginGetResponse : AsyncCallback * obj -> IAsyncResult

Public Overridable Function BeginGetResponse (callback As AsyncCallback, state As Object) As IAsyncResult

Parametreler

callback

AsyncCallback

AsyncCallback temsilcisi.

state

Object

Bu zaman uyumsuz istek için durum bilgilerini içeren bir nesne.

Döndürülenler

IAsyncResult

Zaman uyumsuz isteğe başvuran bir IAsyncResult.

Özel durumlar

NotImplementedException

Yöntemi alt sınıfta geçersiz kılınmadığında yöntemine erişmek için herhangi bir girişimde bulunulması.

Örnekler

Aşağıdaki örnek, hedef kaynağı zaman uyumsuz olarak istemek için BeginGetResponse kullanır. Kaynak elde edildiğinde, belirtilen geri çağırma yöntemi yürütülür.

#using <System.dll>

using namespace System;
using namespace System::Net;
using namespace System::IO;
using namespace System::Text;
using namespace System::Threading;
public ref class RequestState
{
private:

   // This class stores the state of the request.
   literal int BUFFER_SIZE = 1024;

public:
   StringBuilder^ requestData;
   array<Byte>^bufferRead;
   WebRequest^ request;
   WebResponse^ response;
   Stream^ responseStream;
   RequestState()
   {
      bufferRead = gcnew array<Byte>(BUFFER_SIZE);
      requestData = gcnew StringBuilder( "" );
      request = nullptr;
      responseStream = nullptr;
   }

};

ref class WebRequest_BeginGetResponse
{
public:
   static ManualResetEvent^ allDone = gcnew ManualResetEvent( false );
   literal int BUFFER_SIZE = 1024;
   static void RespCallback( IAsyncResult^ asynchronousResult )
   {
      try
      {
         
         // Set the State of request to asynchronous.
         RequestState^ myRequestState = dynamic_cast<RequestState^>(asynchronousResult->AsyncState);
         WebRequest^ myWebRequest1 = myRequestState->request;
         
         // End the Asynchronous response.
         myRequestState->response = myWebRequest1->EndGetResponse( asynchronousResult );
         
         // Read the response into a 'Stream' object.
         Stream^ responseStream = myRequestState->response->GetResponseStream();
         myRequestState->responseStream = responseStream;
         
         // Begin the reading of the contents of the HTML page and print it to the console.
         IAsyncResult^ asynchronousResultRead = responseStream->BeginRead( myRequestState->bufferRead, 0, BUFFER_SIZE, gcnew AsyncCallback( ReadCallBack ), myRequestState );
      }
      catch ( WebException^ e ) 
      {
         Console::WriteLine( "WebException raised!" );
         Console::WriteLine( "\n {0}", e->Message );
         Console::WriteLine( "\n {0}", e->Status );
      }
      catch ( Exception^ e ) 
      {
         Console::WriteLine( "Exception raised!" );
         Console::WriteLine( "Source : {0}", e->Source );
         Console::WriteLine( "Message : {0}", e->Message );
      }

   }

   static void ReadCallBack( IAsyncResult^ asyncResult )
   {
      try
      {
         
         // Result state is set to AsyncState.
         RequestState^ myRequestState = dynamic_cast<RequestState^>(asyncResult->AsyncState);
         Stream^ responseStream = myRequestState->responseStream;
         int read = responseStream->EndRead( asyncResult );
         
         // Read the contents of the HTML page and then print to the console.
         if ( read > 0 )
         {
            myRequestState->requestData->Append( Encoding::ASCII->GetString( myRequestState->bufferRead, 0, read ) );
            IAsyncResult^ asynchronousResult = responseStream->BeginRead( myRequestState->bufferRead, 0, BUFFER_SIZE, gcnew AsyncCallback( ReadCallBack ), myRequestState );
         }
         else
         {
            Console::WriteLine( "\nThe HTML page Contents are:  " );
            if ( myRequestState->requestData->Length > 1 )
            {
               String^ sringContent;
               sringContent = myRequestState->requestData->ToString();
               Console::WriteLine( sringContent );
            }
            Console::WriteLine( "\nPress 'Enter' key to continue........" );
            responseStream->Close();
            allDone->Set();
         }
      }
      catch ( WebException^ e ) 
      {
         Console::WriteLine( "WebException raised!" );
         Console::WriteLine( "\n {0}", e->Message );
         Console::WriteLine( "\n {0}", e->Status );
      }
      catch ( Exception^ e ) 
      {
         Console::WriteLine( "Exception raised!" );
         Console::WriteLine( "Source : {0}", e->Source );
         Console::WriteLine( "Message : {0}", e->Message );
      }

   }

};

int main()
{
   try
   {
      
      // Create a new webrequest to the mentioned URL.
      WebRequest^ myWebRequest = WebRequest::Create( "http://www.contoso.com" );
      
      // Please, set the proxy to a correct value.
      WebProxy^ proxy = gcnew WebProxy( "myproxy:80" );
      proxy->Credentials = gcnew NetworkCredential( "srikun","simrin123" );
      myWebRequest->Proxy = proxy;
      
      // Create a new instance of the RequestState.
      RequestState^ myRequestState = gcnew RequestState;
      
      // The 'WebRequest' object is associated to the 'RequestState' object.
      myRequestState->request = myWebRequest;
      
      // Start the Asynchronous call for response.
      IAsyncResult^ asyncResult = dynamic_cast<IAsyncResult^>(myWebRequest->BeginGetResponse( gcnew AsyncCallback( WebRequest_BeginGetResponse::RespCallback ), myRequestState ));
      WebRequest_BeginGetResponse::allDone->WaitOne();
      
      // Release the WebResponse resource.
      myRequestState->response->Close();
      Console::Read();
   }
   catch ( WebException^ e ) 
   {
      Console::WriteLine( "WebException raised!" );
      Console::WriteLine( "\n {0}", e->Message );
      Console::WriteLine( "\n {0}", e->Status );
   }
   catch ( Exception^ e ) 
   {
      Console::WriteLine( "Exception raised!" );
      Console::WriteLine( "Source : {0}", e->Source );
      Console::WriteLine( "Message : {0}", e->Message );
   }

}

using System;
using System.Net;
using System.IO;
using System.Text;
using System.Threading;

public class RequestState
{
  // This class stores the state of the request.
  const int BUFFER_SIZE = 1024;
  public StringBuilder requestData;
  public byte[] bufferRead;
  public WebRequest request;
  public WebResponse response;
  public Stream responseStream;
  public RequestState()
  {
    bufferRead = new byte[BUFFER_SIZE];
    requestData = new StringBuilder("");
    request = null;
    responseStream = null;
  }
}
class WebRequest_BeginGetResponse
{
  public static ManualResetEvent allDone= new ManualResetEvent(false);
  const int BUFFER_SIZE = 1024;
  static void Main()
  {
    try
    {
      // Create a new webrequest to the mentioned URL.   
      WebRequest myWebRequest= WebRequest.Create("http://www.contoso.com");
      
      // Please, set the proxy to a correct value. 
      WebProxy proxy=new WebProxy("myproxy:80");

      proxy.Credentials=new NetworkCredential("srikun","simrin123");
      myWebRequest.Proxy=proxy;
      // Create a new instance of the RequestState.
      RequestState myRequestState = new RequestState();
      // The 'WebRequest' object is associated to the 'RequestState' object.
      myRequestState.request = myWebRequest;
      // Start the Asynchronous call for response.
      IAsyncResult asyncResult=(IAsyncResult) myWebRequest.BeginGetResponse(new AsyncCallback(RespCallback),myRequestState);
      allDone.WaitOne();
      // Release the WebResponse resource.
      myRequestState.response.Close();
      Console.Read();
    }
    catch(WebException e)
    {
      Console.WriteLine("WebException raised!");
      Console.WriteLine("\n{0}",e.Message);
      Console.WriteLine("\n{0}",e.Status);
    } 
    catch(Exception e)
    {
      Console.WriteLine("Exception raised!");
      Console.WriteLine("Source : " + e.Source);
      Console.WriteLine("Message : " + e.Message);
    }
  }
  private static void RespCallback(IAsyncResult asynchronousResult)
  {  
    try
    {
      // Set the State of request to asynchronous.
      RequestState myRequestState=(RequestState) asynchronousResult.AsyncState;
      WebRequest  myWebRequest1=myRequestState.request;
      // End the Asynchronous response.
      myRequestState.response =  myWebRequest1.EndGetResponse(asynchronousResult);
      // Read the response into a 'Stream' object.
      Stream responseStream = myRequestState.response.GetResponseStream();
      myRequestState.responseStream=responseStream;
      // Begin the reading of the contents of the HTML page and print it to the console.
      IAsyncResult asynchronousResultRead = responseStream.BeginRead(myRequestState.bufferRead, 0, BUFFER_SIZE, new AsyncCallback(ReadCallBack), myRequestState);
    }
    catch(WebException e)
    {
      Console.WriteLine("WebException raised!");
      Console.WriteLine("\n{0}",e.Message);
      Console.WriteLine("\n{0}",e.Status);
    } 
    catch(Exception e)
    {
      Console.WriteLine("Exception raised!");
      Console.WriteLine("Source : " + e.Source);
      Console.WriteLine("Message : " + e.Message);
    }
  }
  private static  void ReadCallBack(IAsyncResult asyncResult)
  {
    try
    {
      // Result state is set to AsyncState.
      RequestState myRequestState = (RequestState)asyncResult.AsyncState;
      Stream responseStream = myRequestState.responseStream;
      int read = responseStream.EndRead( asyncResult );
      // Read the contents of the HTML page and then print to the console.
      if (read > 0)
      {
        myRequestState.requestData.Append(Encoding.ASCII.GetString(myRequestState.bufferRead, 0, read));
        IAsyncResult asynchronousResult = responseStream.BeginRead( myRequestState.bufferRead, 0, BUFFER_SIZE, new AsyncCallback(ReadCallBack), myRequestState);
      }
      else
      {
        Console.WriteLine("\nThe HTML page Contents are:  ");
        if(myRequestState.requestData.Length>1)
        {
          string sringContent;
          sringContent = myRequestState.requestData.ToString();
          Console.WriteLine(sringContent);
        }
        Console.WriteLine("\nPress 'Enter' key to continue........");
        responseStream.Close();
        allDone.Set();
      }
    }
    catch(WebException e)
    {
      Console.WriteLine("WebException raised!");
      Console.WriteLine("\n{0}",e.Message);
      Console.WriteLine("\n{0}",e.Status);
    } 
    catch(Exception e)
    {
      Console.WriteLine("Exception raised!");
      Console.WriteLine("Source : {0}" , e.Source);
      Console.WriteLine("Message : {0}" , e.Message);
    }
  }
}

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

Public Class RequestState
  ' This class stores the state of the request
  Private Shared BUFFER_SIZE As Integer = 1024
  Public requestData As StringBuilder
  Public bufferRead() As Byte
  Public request As WebRequest
  Public response As WebResponse
  Public responseStream As Stream
  
  Public Sub New()
    bufferRead = New Byte(BUFFER_SIZE) {}
    requestData = New StringBuilder("")
    request = Nothing
    responseStream = Nothing
  End Sub
End Class

Class WebRequest_BeginGetResponse
  Public Shared allDone As New ManualResetEvent(False)
  Private Shared BUFFER_SIZE As Integer = 1024
  
  Shared Sub Main()
    Try


      ' Create a new webrequest to the mentioned URL.
      Dim myWebRequest As WebRequest = WebRequest.Create("http://www.contoso.com")
      'Please, set the proxy to a correct value.
      Dim proxy As New WebProxy("itgproxy:80")
      proxy.Credentials = New NetworkCredential("srikun", "simrin123")
      myWebRequest.Proxy = proxy
      ' Create a new instance of the RequestState.
      Dim myRequestState As New RequestState()
      ' The 'WebRequest' object is associated to the 'RequestState' object.
      myRequestState.request = myWebRequest
      ' Start the Asynchronous call for response.
      Dim asyncResult As IAsyncResult = CType(myWebRequest.BeginGetResponse(AddressOf RespCallback, myRequestState), IAsyncResult)
      allDone.WaitOne()
      ' Release the WebResponse resource.
      myRequestState.response.Close()
      Console.Read()
    Catch e As WebException
      Console.WriteLine("WebException raised!")
      Console.WriteLine(ControlChars.Cr + "{0}", e.Message)
      Console.WriteLine(ControlChars.Cr + "{0}", e.Status)
    Catch e As Exception
      Console.WriteLine("Exception raised!")
      Console.WriteLine(("Source : " + e.Source))
      Console.WriteLine(("Message : " + e.Message))
    End Try
  End Sub

  Private Shared Sub RespCallback(asynchronousResult As IAsyncResult)
    Try
      ' Set the State of request to asynchronous.
      Dim myRequestState As RequestState = CType(asynchronousResult.AsyncState, RequestState)
      Dim myWebRequest1 As WebRequest = myRequestState.request
      ' End the Asynchronous response.
      myRequestState.response = myWebRequest1.EndGetResponse(asynchronousResult)
      ' Read the response into a 'Stream' object.
      Dim responseStream As Stream = myRequestState.response.GetResponseStream()
      myRequestState.responseStream = responseStream
      ' Begin the reading of the contents of the HTML page and print it to the console.
      Dim asynchronousResultRead As IAsyncResult = responseStream.BeginRead(myRequestState.bufferRead, 0, BUFFER_SIZE, AddressOf ReadCallBack, myRequestState)
    Catch e As WebException
      Console.WriteLine("WebException raised!")
      Console.WriteLine(ControlChars.Cr + "{0}", e.Message)
      Console.WriteLine(ControlChars.Cr + "{0}", e.Status)
    Catch e As Exception
      Console.WriteLine("Exception raised!")
      Console.WriteLine(("Source : " + e.Source))
      Console.WriteLine(("Message : " + e.Message))
    End Try
  End Sub
  Private Shared Sub ReadCallBack(asyncResult As IAsyncResult)
    Try
      ' Result state is set to AsyncState.
      Dim myRequestState As RequestState = CType(asyncResult.AsyncState, RequestState)
      Dim responseStream As Stream = myRequestState.responseStream
      Dim read As Integer = responseStream.EndRead(asyncResult)
      ' Read the contents of the HTML page and then print to the console.
      If read > 0 Then
        myRequestState.requestData.Append(Encoding.ASCII.GetString(myRequestState.bufferRead, 0, read))
        Dim asynchronousResult As IAsyncResult = responseStream.BeginRead(myRequestState.bufferRead, 0, BUFFER_SIZE, AddressOf ReadCallBack, myRequestState)
      Else
        Console.WriteLine(ControlChars.Cr + "The HTML page Contents are:  ")
        If myRequestState.requestData.Length > 1 Then
          Dim sringContent As String
          sringContent = myRequestState.requestData.ToString()
          Console.WriteLine(sringContent)
        End If
        Console.WriteLine(ControlChars.Cr + "Press 'Enter' key to continue........")
        responseStream.Close()
           allDone.Set()
      End If
    Catch e As WebException
      Console.WriteLine("WebException raised!")
      Console.WriteLine(ControlChars.Cr + "{0}", e.Message)
      Console.WriteLine(ControlChars.Cr + "{0}", e.Status)
    Catch e As Exception
      Console.WriteLine("Exception raised!")
      Console.WriteLine("Source :{0} ", e.Source)
      Console.WriteLine("Message :{0} ", e.Message)
    End Try
  End Sub

End Class

Açıklamalar

Dikkat

WebRequest, HttpWebRequest, ServicePointve WebClient kullanım dışıdır ve bunları yeni geliştirme için kullanmamalısınız. Bunun yerine HttpClient kullanın.

BeginGetResponse yöntemi yanıt için zaman uyumsuz bir istek başlatır. AsyncCallback temsilcisini uygulayan geri çağırma yöntemi, İnternet kaynağından WebResponse döndürmek için EndGetResponse yöntemini kullanır.

Not

WebRequest sınıfı bir abstract sınıfıdır. çalışma zamanında WebRequest örneklerinin gerçek davranışı, WebRequest.Create yöntemi tarafından döndürülen alt sınıf tarafından belirlenir. Varsayılan değerler ve özel durumlar hakkında daha fazla bilgi için HttpWebRequest ve FileWebRequestgibi alt sınıfların belgelerine bakın.

Not

WebException oluşturulursa, sunucudan yanıtı belirlemek için özel durumun Response ve Status özelliklerini kullanın.

Ayrıca bkz.

• EndGetResponse(IAsyncResult)
• GetResponse()
• Zaman Uyumsuz İstekler Yapma