HttpWebRequest.BeginGetRequestStream(AsyncCallback, Object) Metode

Definisi

Ruang nama:

System.Net

Rakitan:

System.Net.Requests.dll

Sumber:

HttpWebRequest.cs

Memulai permintaan asinkron untuk objek yang Stream digunakan untuk menulis 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

callback

AsyncCallback

Delegasi AsyncCallback .

state

Object

Objek status untuk permintaan ini.

Mengembalikan

IAsyncResult

Yang IAsyncResult mereferensikan permintaan asinkron.

Pengecualian

ProtocolViolationException

Properti Method ini adalah GET atau HEAD.

-atau-

KeepAliveadalah true, AllowWriteStreamBuffering adalah , ContentLength adalah false-1, SendChunked adalah false, dan Method MERUPAKAN POST atau PUT.

InvalidOperationException

Aliran sedang digunakan oleh panggilan sebelumnya ke BeginGetRequestStream(AsyncCallback, Object)

-atau-

TransferEncoding diatur ke nilai dan SendChunked adalah false.

-atau-

Kumpulan utas kehabisan utas.

NotSupportedException

Validator cache permintaan menunjukkan bahwa respons untuk permintaan ini dapat dilayani dari cache; namun, permintaan yang menulis data tidak boleh menggunakan cache. Pengecualian ini dapat terjadi jika Anda menggunakan validator cache kustom yang salah diimplementasikan.

WebException

Abort() sebelumnya dipanggil.

ObjectDisposedException

Dalam aplikasi .NET Compact Framework, aliran permintaan dengan panjang konten nol tidak diperoleh dan ditutup dengan benar. Untuk informasi selengkapnya tentang menangani permintaan panjang konten nol, lihat Pemrograman Jaringan di .NET Compact Framework.

Contoh

Contoh kode berikut menggunakan BeginGetRequestStream metode untuk membuat permintaan asinkron untuk instans stream.

#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

Keterangan

Metode memulai BeginGetRequestStream permintaan asinkron untuk aliran yang digunakan untuk mengirim data untuk HttpWebRequest. Metode panggilan balik asinkron menggunakan EndGetRequestStream metode untuk mengembalikan aliran aktual.

Metode ini BeginGetRequestStream memerlukan beberapa tugas penyiapan sinkron untuk diselesaikan (resolusi DNS, deteksi proksi, dan koneksi soket TCP, misalnya) sebelum metode ini menjadi asinkron. Akibatnya, metode ini tidak boleh dipanggil pada utas antarmuka pengguna (UI) karena mungkin perlu waktu yang cukup lama (hingga beberapa menit tergantung pada pengaturan jaringan) untuk menyelesaikan tugas penyiapan sinkron awal sebelum pengecualian untuk kesalahan dilemparkan atau metode berhasil.

Untuk mempelajari selengkapnya tentang kumpulan utas, lihat Kumpulan utas terkelola.

Catatan

Aplikasi Anda tidak dapat mencampur metode sinkron dan asinkron untuk permintaan tertentu. Jika Anda memanggil BeginGetRequestStream metode , Anda harus menggunakan BeginGetResponse metode untuk mengambil respons.

Catatan

Anggota ini mengeluarkan informasi pelacakan saat Anda mengaktifkan pelacakan jaringan di aplikasi Anda. Untuk informasi selengkapnya, lihat Pelacakan Jaringan di .NET Framework.

Lihat juga

• Elemen DefaultProxy (Pengaturan Jaringan)