WebRequest.BeginGetRequestStream(AsyncCallback, Object) Methode
Definition
Wichtig
Einige Informationen beziehen sich auf Vorabversionen, die vor dem Release ggf. grundlegend überarbeitet werden. Microsoft übernimmt hinsichtlich der hier bereitgestellten Informationen keine Gewährleistungen, seien sie ausdrücklich oder konkludent.
Stellt beim Überschreiben in einer Nachfolgerklasse eine asynchrone Version der GetRequestStream()-Methode bereit.
public:
abstract IAsyncResult ^ BeginGetRequestStream(AsyncCallback ^ callback, System::Object ^ state);
public:
virtual IAsyncResult ^ BeginGetRequestStream(AsyncCallback ^ callback, System::Object ^ state);
public abstract IAsyncResult BeginGetRequestStream (AsyncCallback callback, object state);
public virtual IAsyncResult BeginGetRequestStream (AsyncCallback? callback, object? state);
public virtual IAsyncResult BeginGetRequestStream (AsyncCallback callback, object state);
abstract member BeginGetRequestStream : AsyncCallback * obj -> IAsyncResult
abstract member BeginGetRequestStream : AsyncCallback * obj -> IAsyncResult
override this.BeginGetRequestStream : AsyncCallback * obj -> IAsyncResult
Public MustOverride Function BeginGetRequestStream (callback As AsyncCallback, state As Object) As IAsyncResult
Public Overridable Function BeginGetRequestStream (callback As AsyncCallback, state As Object) As IAsyncResult
Parameter
- callback
- AsyncCallback
Der AsyncCallback -Delegat.
- state
- Object
Ein Objekt mit Zustandsinformationen für diese asynchrone Anforderung.
Gibt zurück
Ein IAsyncResult, das auf die asynchrone Anforderung verweist.
Ausnahmen
Es wurde versucht, auf die Methode zuzugreifen, obwohl die Methode in einer Nachfolgerklasse nicht überschrieben wurde.
Beispiele
Im folgenden Beispiel wird der verwendet, BeginGetRequestStream um den Anforderungsstream asynchron abzurufen.
#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
{
public:
// This class stores the request state of the request.
WebRequest^ request;
RequestState()
{
request = nullptr;
}
};
ref class WebRequest_BeginGetRequeststream
{
public:
static ManualResetEvent^ allDone = gcnew ManualResetEvent( false );
static void ReadCallback( IAsyncResult^ asynchronousResult )
{
RequestState^ myRequestState = dynamic_cast<RequestState^>(asynchronousResult->AsyncState);
WebRequest^ myWebRequest = myRequestState->request;
// End of the Asynchronus request.
Stream^ streamResponse = myWebRequest->EndGetRequestStream( asynchronousResult );
// Create a string that is to be posted to the uri.
Console::WriteLine( "Please enter a string to be posted:" );
String^ postData = Console::ReadLine();
// Convert the string into a Byte array.
array<Byte>^byteArray = Encoding::UTF8->GetBytes( postData );
// Write data to the stream.
streamResponse->Write( byteArray, 0, postData->Length );
streamResponse->Close();
allDone->Set();
}
};
int main()
{
// Create a new request to the mentioned URL.
WebRequest^ myWebRequest = WebRequest::Create( "http://www.contoso.com" );
// Create an instance of the RequestState and assign 'myWebRequest' to its request field.
RequestState^ myRequestState = gcnew RequestState;
myRequestState->request = myWebRequest;
myWebRequest->ContentType = "application/x-www-form-urlencoded";
// Set the 'Method' prperty to 'POST' to post data to a Uri.
myRequestState->request->Method = "POST";
// Start the Asynchronous 'BeginGetRequestStream' method call.
IAsyncResult^ r = dynamic_cast<IAsyncResult^>(myWebRequest->BeginGetRequestStream( gcnew AsyncCallback( WebRequest_BeginGetRequeststream::ReadCallback ), myRequestState ));
WebRequest_BeginGetRequeststream::allDone->WaitOne();
WebResponse^ myWebResponse = myWebRequest->GetResponse();
Console::WriteLine( "The String* entered has been posted." );
Console::WriteLine( "Please wait for the response..." );
Stream^ streamResponse = myWebResponse->GetResponseStream();
StreamReader^ streamRead = gcnew StreamReader( streamResponse );
array<Char>^readBuff = gcnew array<Char>(256);
int count = streamRead->Read( readBuff, 0, 256 );
Console::WriteLine( "The contents of the HTML page are " );
while ( count > 0 )
{
String^ outputData = gcnew String( readBuff,0,count );
Console::Write( outputData );
count = streamRead->Read( readBuff, 0, 256 );
}
streamResponse->Close();
streamRead->Close();
// Release the HttpWebResponse Resource.
myWebResponse->Close();
}
using System;
using System.Net;
using System.IO;
using System.Text;
using System.Threading;
public class RequestState
{
// This class stores the request state of the request.
public WebRequest request;
public RequestState()
{
request = null;
}
}
class WebRequest_BeginGetRequeststream
{
public static ManualResetEvent allDone= new ManualResetEvent(false);
static void Main()
{
// Create a new request to the mentioned URL.
WebRequest myWebRequest= WebRequest.Create("http://www.contoso.com");
// Create an instance of the RequestState and assign
// 'myWebRequest' to it's request field.
RequestState myRequestState = new RequestState();
myRequestState.request = myWebRequest;
myWebRequest.ContentType="application/x-www-form-urlencoded";
// Set the 'Method' property to 'POST' to post data to a Uri.
myRequestState.request.Method="POST";
// Start the Asynchronous 'BeginGetRequestStream' method call.
IAsyncResult r=(IAsyncResult) myWebRequest.BeginGetRequestStream(
new AsyncCallback(ReadCallback),myRequestState);
// Pause the current thread until the async operation completes.
Console.WriteLine("main thread waiting...");
allDone.WaitOne();
// Assign the response object of 'WebRequest' to a 'WebResponse' variable.
WebResponse myWebResponse = myWebRequest.GetResponse();
Console.WriteLine("The string has been posted.");
Console.WriteLine("Please wait for the response...");
Stream streamResponse = myWebResponse.GetResponseStream();
StreamReader streamRead = new StreamReader( streamResponse );
Char[] readBuff = new Char[256];
int count = streamRead.Read( readBuff, 0, 256 );
Console.WriteLine("\nThe contents of the HTML page are ");
while (count > 0)
{
String outputData = new String(readBuff, 0, count);
Console.Write(outputData);
count = streamRead.Read(readBuff, 0, 256);
}
// Close the Stream Object.
streamResponse.Close();
streamRead.Close();
// Release the HttpWebResponse Resource.
myWebResponse.Close();
}
private static void ReadCallback(IAsyncResult asynchronousResult)
{
RequestState myRequestState =(RequestState) asynchronousResult.AsyncState;
WebRequest myWebRequest = myRequestState.request;
// End the Asynchronous request.
Stream streamResponse = myWebRequest.EndGetRequestStream(asynchronousResult);
// Create a string that is to be posted to the uri.
Console.WriteLine("Please enter a string to be posted:");
string postData = Console.ReadLine();
// Convert the string into a byte array.
byte[] byteArray = Encoding.UTF8.GetBytes(postData);
// Write the data to the stream.
streamResponse.Write(byteArray,0,postData.Length);
streamResponse.Close();
allDone.Set();
}
}
Imports System.Net
Imports System.IO
Imports System.Text
Imports System.Threading
Public Class RequestState
' This class stores the request state of the request.
Public request As WebRequest
Public Sub New()
request = Nothing
End Sub
End Class
Class WebRequest_BeginGetRequeststream
Public Shared allDone As New ManualResetEvent(False)
Shared Sub Main()
' Create a new request.
Dim myWebRequest As WebRequest = WebRequest.Create("http://www.contoso.com/codesnippets/next.asp")
' Create an instance of the RequestState and assign
' myWebRequest' to it's request field.
Dim myRequestState As New RequestState()
myRequestState.request = myWebRequest
myWebRequest.ContentType = "application/x-www-form-urlencoded"
' Set the 'Method' property to 'POST' to post data to a Uri.
myRequestState.request.Method = "POST"
' Start the asynchronous 'BeginGetRequestStream' method call.
Dim r As IAsyncResult = CType(myWebRequest.BeginGetRequestStream(AddressOf ReadCallback, myRequestState), IAsyncResult)
' Pause the current thread until the async operation completes.
allDone.WaitOne()
' Send the Post and get the response.
Dim myWebResponse As WebResponse = myWebRequest.GetResponse()
Console.WriteLine(ControlChars.Cr + "The string has been posted.")
Console.WriteLine("Please wait for the response....")
Dim streamResponse As Stream = myWebResponse.GetResponseStream()
Dim streamRead As New StreamReader(streamResponse)
Dim readBuff(256) As [Char]
Dim count As Integer = streamRead.Read(readBuff, 0, 256)
Console.WriteLine(ControlChars.Cr + "The contents of the HTML page are ")
While count > 0
Dim outputData As New [String](readBuff, 0, count)
Console.WriteLine(outputData)
count = streamRead.Read(readBuff, 0, 256)
End While
' Close the Stream Object.
streamResponse.Close()
streamRead.Close()
' Release the HttpWebResponse Resource.
myWebResponse.Close()
End Sub
Private Shared Sub ReadCallback(asynchronousResult As IAsyncResult)
Dim myRequestState As RequestState = CType(asynchronousResult.AsyncState, RequestState)
Dim myWebRequest As WebRequest = myRequestState.request
' End the request.
Dim streamResponse As Stream = myWebRequest.EndGetRequestStream(asynchronousResult)
' Create a string that is to be posted to the uri.
Console.WriteLine(ControlChars.Cr + "Please enter a string to be posted:")
Dim postData As String = Console.ReadLine()
Dim encoder As New ASCIIEncoding()
' Convert the string into a byte array.
Dim byteArray As Byte() = Encoding.UTF8.GetBytes(postData)
' Write the data to the stream.
streamResponse.Write(byteArray, 0, postData.Length)
streamResponse.Close()
' Allow the main thread to resume.
allDone.Set()
End Sub
End Class
Hinweise
Die BeginGetRequestStream -Methode startet eine asynchrone Anforderung für einen Stream, der zum Senden von Daten an eine Internetressource verwendet wird. Die Rückrufmethode, die den AsyncCallback Delegaten implementiert, verwendet die EndGetRequestStream -Methode, um den Anforderungsstream zurückzugeben.
Hinweis
Die WebRequest -Klasse ist eine abstract
Klasse. Das tatsächliche Verhalten von WebRequest Instanzen zur Laufzeit wird durch die von der WebRequest.Create -Methode zurückgegebene untergeordnete Klasse bestimmt. Weitere Informationen zu Standardwerten und Ausnahmen finden Sie in der Dokumentation für die untergeordneten Klassen, z. B HttpWebRequest . und FileWebRequest.
Gilt für:
Weitere Informationen
Feedback
https://aka.ms/ContentUserFeedback.
Bald verfügbar: Im Laufe des Jahres 2024 werden wir GitHub-Issues stufenweise als Feedbackmechanismus für Inhalte abbauen und durch ein neues Feedbacksystem ersetzen. Weitere Informationen finden Sie unterFeedback senden und anzeigen für