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WebRequest.BeginGetRequestStream (Método)

Cuando se reemplaza en una clase descendiente, proporciona una versión asincrónica del método GetRequestStream.

Espacio de nombres: System.Net
Ensamblado: System (en system.dll)

public virtual IAsyncResult BeginGetRequestStream (
	AsyncCallback callback,
	Object state
)
public IAsyncResult BeginGetRequestStream (
	AsyncCallback callback, 
	Object state
)
public function BeginGetRequestStream (
	callback : AsyncCallback, 
	state : Object
) : IAsyncResult

Parámetros

callback

Delegado AsyncCallback.

state

Objeto que contiene información de estado para esta solicitud asincrónica.

Valor devuelto

IAsyncResult que hace referencia a la solicitud asincrónica.

Tipo de excepciónCondición

NotImplementedException

Se intenta por todos los medios tener acceso al método, cuando el método no se reemplaza en una clase descendiente.

El método BeginGetRequestStream inicia una solicitud asincrónica de una secuencia que se usa para enviar datos a un recurso de Internet. El método de devolución de llamada que implementa el delegado AsyncCallback usa el método EndGetRequestStream para devolver la secuencia de solicitud.

NotaNota

La clase WebRequest es una clase abstract. El comportamiento real de las instancias de WebRequest en tiempo de ejecución viene determinado por la clase descendiente devuelta por el método System.Net.WebRequest.Create. Para obtener más información acerca de los valores predeterminados y las excepciones, consulte la documentación de las clases descendientes, como HttpWebRequest y FileWebRequest.

En el ejemplo siguiente se utiliza el método BeginGetRequestStream para obtener asincrónicamente la secuencia de solicitud.

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 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.
            byte[] byteArray = Encoding.UTF8.GetBytes(postData);

            // Write the data to the stream.
            streamResponse.Write(byteArray,0,postData.Length);
            streamResponse.Close();
            allDone.Set();
    }
}

import System.*;
import System.Net.*;
import System.IO.*;
import System.Text.*;
import System.Threading.*;
public class RequestState
{
    // This class stores the request state of the request.
    public WebRequest request;

    public RequestState()
    {
        request = null;
    } //RequestState
} //RequestState

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

    public static void main(String[] args)
    {
        // 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.set_ContentType("application/x-www-form-urlencoded");
        // Set the 'Method' property  to 'POST' to post data to a Uri.
        myRequestState.request.set_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();
    } //main

    private static void ReadCallback(IAsyncResult asynchronousResult)
    {
        RequestState myRequestState = 
            (RequestState) asynchronousResult.get_AsyncState();
        WebRequest myWebRequest = myRequestState.request;
        // End 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.
        ubyte byteArray[] = Encoding.get_UTF8().GetBytes(postData);
        // Write the data to the stream.
        streamResponse.Write(byteArray, 0, postData.get_Length());
        streamResponse.Close();
        allDone.Set();
    } //ReadCallback
} //WebRequest_BeginGetRequeststream

Windows 98, Windows 2000 SP4, Windows CE, Windows Millennium, Windows Mobile para Pocket PC, Windows Mobile para Smartphone, Windows Server 2003, Windows XP Media Center, Windows XP Professional x64, Windows XP SP2, Windows XP Starter Edition

.NET Framework no admite todas las versiones de cada plataforma. Para obtener una lista de las versiones admitidas, vea Requisitos del sistema.

.NET Framework

Compatible con: 2.0, 1.1, 1.0

.NET Compact Framework

Compatible con: 2.0, 1.0

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