HttpWebRequest.BeginGetRequestStream(AsyncCallback, Object) HttpWebRequest.BeginGetRequestStream(AsyncCallback, Object) HttpWebRequest.BeginGetRequestStream(AsyncCallback, Object) HttpWebRequest.BeginGetRequestStream(AsyncCallback, Object) Method

Definition

Startet eine asynchrone Anforderung eines Stream-Objekts, das zum Schreiben von Daten verwendet werden soll.Begins an asynchronous request for a Stream object to use to write data.

public:
 override IAsyncResult ^ BeginGetRequestStream(AsyncCallback ^ callback, System::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

Parameter

state
Object Object Object Object

Das Zustandsobjekt für diese Anforderung.The state object for this request.

Gibt zurück

Ein IAsyncResult, das auf die asynchrone Anforderung verweist.An IAsyncResult that references the asynchronous request.

Ausnahmen

Die Method-Eigenschaft ist GET oder HEAD.The Method property is GET or HEAD.

- oder --or- KeepAlive ist true, AllowWriteStreamBuffering ist false, ContentLength ist -1, SendChunked ist false, und Method ist POST oder PUT.KeepAlive is true, AllowWriteStreamBuffering is false, ContentLength is -1, SendChunked is false, and Method is POST or PUT.

Der Stream wird von einem vorherigen Aufruf von BeginGetRequestStream(AsyncCallback, Object) verwendet.The stream is being used by a previous call to BeginGetRequestStream(AsyncCallback, Object)

- oder --or- TransferEncoding ist auf einen Wert festgelegt, und SendChunked ist false.TransferEncoding is set to a value and SendChunked is false.

- oder --or- Der Threadpool enthält nicht mehr genügend Threads.The thread pool is running out of threads.

Die Cachebestätigung der Anforderung hat angegeben, dass die Antwort für diese Anforderung vom Cache bereitgestellt werden kann. Anforderungen, die Daten schreiben, dürfen jedoch den Cache nicht verwenden.The request cache validator indicated that the response for this request can be served from the cache; however, requests that write data must not use the cache. Diese Ausnahme kann auftreten, wenn Sie eine benutzerdefinierte Cachebestätigung verwenden, die nicht ordnungsgemäß implementiert wurde.This exception can occur if you are using a custom cache validator that is incorrectly implemented.

Abort() wurde bereits aufgerufen.Abort() was previously called.

In einer .NET Compact Framework-Anwendung wurde ein Anforderungsstream, dessen Inhalt die Länge 0 (null) hat, nicht korrekt abgerufen und geschlossen.In a .NET Compact Framework application, a request stream with zero content length was not obtained and closed correctly. Weitere Informationen über das Verarbeiten von Anforderungen mit einem Inhalt der Länge 0 (null) finden Sie unter Network Programming in the .NET Compact Framework (Netzwerkprogrammierung in .NET Compact Framework.).For more information about handling zero content length requests, see Network Programming in the .NET Compact Framework.

Beispiele

Im folgenden Codebeispiel wird die BeginGetRequestStream -Methode verwendet, um eine asynchrone Anforderung für eine Streaminstanz vorzunehmen.The following code example uses the BeginGetRequestStream method to make an asynchronous request for a stream instance.

#using <System.dll>

using namespace System;
using namespace System::Net;
using namespace System::IO;
using namespace System::Text;
using namespace System::Threading;
ref class HttpWebRequestBeginGetRequest
{
public:
   static ManualResetEvent^ allDone = gcnew ManualResetEvent( false );
   static void Main()
   {
      
      // Create a new HttpWebRequest object.
      HttpWebRequest^ request = dynamic_cast<HttpWebRequest^>(WebRequest::Create( "http://www.contoso.com/example.aspx" ));
      
      // Set the ContentType property.
      request->ContentType = "application/x-www-form-urlencoded";
      
      // Set the Method property to 'POST' to post data to the Uri.
      request->Method = "POST";
      
      // Start the asynchronous operation.    
      AsyncCallback^ del = gcnew AsyncCallback(GetRequestStreamCallback);
      request->BeginGetRequestStream( del, request );
      
      // Keep the main thread from continuing while the asynchronous
      // operation completes. A real world application
      // could do something useful such as updating its user interface. 
      allDone->WaitOne();
    }
      

private:
    static void GetRequestStreamCallback(IAsyncResult^ asynchronousResult)
    {
        HttpWebRequest^ request = dynamic_cast<HttpWebRequest^>(asynchronousResult->AsyncState);
        
        // End the operation
        Stream^ postStream = request->EndGetRequestStream(asynchronousResult);

        Console::WriteLine("Please enter the input data to be posted:");
        String^ postData = Console::ReadLine();

        // Convert the string into a byte array.
        array<Byte>^ByteArray = Encoding::UTF8->GetBytes(postData);

        // Write to the request stream.
        postStream->Write(ByteArray, 0, postData->Length);
        postStream->Close();

        // Start the asynchronous operation to get the response
        AsyncCallback^ del = gcnew AsyncCallback(GetResponseCallback);
        request->BeginGetResponse(del, request);
    }

   static void GetResponseCallback(IAsyncResult^ asynchronousResult)
   {
      HttpWebRequest^ request = dynamic_cast<HttpWebRequest^>(asynchronousResult->AsyncState);

      // End the operation
      HttpWebResponse^ response = dynamic_cast<HttpWebResponse^>(request->EndGetResponse(asynchronousResult));
      Stream^ streamResponse = response->GetResponseStream();
      StreamReader^ streamRead = gcnew StreamReader(streamResponse);
      String^ responseString = streamRead->ReadToEnd();
      Console::WriteLine(responseString);
      // Close the stream object
      streamResponse->Close();
      streamRead->Close();

      // Release the HttpWebResponse
      response->Close();
      allDone->Set();
   }
};

void main()
{
   HttpWebRequestBeginGetRequest::Main();
}

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

class HttpWebRequestBeginGetRequest
{
    private static ManualResetEvent allDone = new ManualResetEvent(false);

    public static void Main(string[] args)
    {


        // Create a new HttpWebRequest object.
        HttpWebRequest request = (HttpWebRequest)WebRequest.Create("http://www.contoso.com/example.aspx");

        request.ContentType = "application/x-www-form-urlencoded";

        // Set the Method property to 'POST' to post data to the URI.
        request.Method = "POST";

        // start the asynchronous operation
        request.BeginGetRequestStream(new AsyncCallback(GetRequestStreamCallback), request);

        // Keep the main thread from continuing while the asynchronous
        // operation completes. A real world application
        // could do something useful such as updating its user interface. 
        allDone.WaitOne();
    }

    private static void GetRequestStreamCallback(IAsyncResult asynchronousResult)
    {
        HttpWebRequest request = (HttpWebRequest)asynchronousResult.AsyncState;
        
        // End the operation
        Stream postStream = request.EndGetRequestStream(asynchronousResult);

        Console.WriteLine("Please enter the input data to be posted:");
        string postData = Console.ReadLine();

        // Convert the string into a byte array.
        byte[] byteArray = Encoding.UTF8.GetBytes(postData);

        // Write to the request stream.
        postStream.Write(byteArray, 0, postData.Length);
        postStream.Close();

        // Start the asynchronous operation to get the response
        request.BeginGetResponse(new AsyncCallback(GetResponseCallback), request);
    }

    private static void GetResponseCallback(IAsyncResult asynchronousResult)
    {
        HttpWebRequest request = (HttpWebRequest)asynchronousResult.AsyncState;

        // End the operation
        HttpWebResponse response = (HttpWebResponse)request.EndGetResponse(asynchronousResult);
        Stream streamResponse = response.GetResponseStream();
        StreamReader streamRead = new StreamReader(streamResponse);
        string responseString = streamRead.ReadToEnd();
        Console.WriteLine(responseString);
        // Close the stream object
        streamResponse.Close();
        streamRead.Close();

        // Release the HttpWebResponse
        response.Close();
        allDone.Set();
    }
}
Imports System.Net
Imports System.IO
Imports System.Text
Imports System.Threading

Class HttpWebRequestBeginGetRequest
    Public Shared allDone As New ManualResetEvent(False)

    Shared Sub Main()


        ' Create a new HttpWebRequest object.
        Dim request As HttpWebRequest = CType(WebRequest.Create("http://www.contoso.com/example.aspx"), _
                 HttpWebRequest)

        ' Set the ContentType property.
        request.ContentType = "application/x-www-form-urlencoded"

        '  Set the Method property to 'POST' to post data to the URI.
        request.Method = "POST"

        ' Start the asynchronous operation.		
        Dim result As IAsyncResult = _
            CType(request.BeginGetRequestStream(AddressOf GetRequestStreamCallback, request), _
            IAsyncResult)

        ' Keep the main thread from continuing while the asynchronous
        ' operation completes. A real world application
        ' could do something useful such as updating its user interface. 
        allDone.WaitOne()
    End Sub

    Private Shared Sub GetRequestStreamCallback(ByVal asynchronousResult As IAsyncResult)
        Dim request As HttpWebRequest = CType(asynchronousResult.AsyncState, HttpWebRequest)
        
        ' End the operation
        Dim postStream As Stream = request.EndGetRequestStream(asynchronousResult)
        Console.WriteLine("Please enter the input data to be posted:")
        Dim postData As [String] = Console.ReadLine()
        
        '  Convert the string into byte array.
        Dim byteArray As Byte() = Encoding.UTF8.GetBytes(postData)

        ' Write to the stream.
        postStream.Write(byteArray, 0, postData.Length)
        postStream.Close()

        ' Start the asynchronous operation to get the response
        Dim result As IAsyncResult = _
            CType(request.BeginGetResponse(AddressOf GetResponseCallback, request), _
            IAsyncResult)
    End Sub

    Private Shared Sub GetResponseCallback(ByVal asynchronousResult As IAsyncResult)
        Dim request As HttpWebRequest = CType(asynchronousResult.AsyncState, HttpWebRequest)
        
        '  Get the response.
        Dim response As HttpWebResponse = CType(request.EndGetResponse(asynchronousResult), _
           HttpWebResponse)
        
        Dim streamResponse As Stream = response.GetResponseStream()
        Dim streamRead As New StreamReader(streamResponse)
        Dim responseString As String = streamRead.ReadToEnd()
        
        Console.WriteLine(responseString)
        
        ' Close Stream object.
        streamResponse.Close()
        streamRead.Close()

        ' Release the HttpWebResponse.
        allDone.Set()
        response.Close()
    End Sub
            
End Class

Hinweise

Die BeginGetRequestStream -Methode startet eine asynchrone Anforderung eines Datenstroms, der zum Senden von HttpWebRequestDaten für das verwendet wird.The BeginGetRequestStream method starts an asynchronous request for a stream used to send data for the HttpWebRequest. Die asynchrone Rückruf Methode verwendet die EndGetRequestStream -Methode, um den eigentlichen Stream zurückzugeben.The asynchronous callback method uses the EndGetRequestStream method to return the actual stream.

Die BeginGetRequestStream -Methode erfordert, dass einige synchrone Setup Tasks ausgeführt werden (z. b. DNS-Auflösung, Proxy Erkennung und TCP-Socketverbindung), bevor diese Methode asynchron wird.The BeginGetRequestStream method requires some synchronous setup tasks to complete (DNS resolution, proxy detection, and TCP socket connection, for example) before this method becomes asynchronous. Folglich sollte diese Methode niemals für einen Benutzeroberflächen Thread (UI) aufgerufen werden, da es viel Zeit in Anspruch nehmen kann (je nach Netzwerkeinstellungen), um die anfänglichen synchronen Setup Aufgaben abzuschließen, bevor eine Ausnahme ausgelöst wird oder die Methode ist erfolgreich.As a result, this method should never be called on a user interface (UI) thread because it might take considerable time (up to several minutes depending on network settings) to complete the initial synchronous setup tasks before an exception for an error is thrown or the method succeeds.

Weitere Informationen zum Thread Pool finden Sie unter der verwaltete Thread Pool.To learn more about the thread pool, see The managed thread pool.

Hinweis

In Ihrer Anwendung können keine synchronen und asynchronen Methoden für eine bestimmte Anforderung gemischt werden.Your application cannot mix synchronous and asynchronous methods for a particular request. Wenn Sie die BeginGetRequestStream -Methode aufrufen, müssen Sie die BeginGetResponse -Methode verwenden, um die Antwort abzurufen.If you call the BeginGetRequestStream method, you must use the BeginGetResponse method to retrieve the response.

Hinweis

Dieser Member gibt Ablaufverfolgungsinformationen aus, wenn Sie die Netzwerkablaufverfolgung in der Anwendung aktivieren.This member outputs trace information when you enable network tracing in your application. Weitere Informationen finden Sie unter Netzwerk Ablauf Verfolgung in der .NET Framework.For more information, see Network Tracing in the .NET Framework.

Gilt für:

Siehe auch