WebRequest.BeginGetResponse メソッド

[アーティクル]
03/28/2008

派生クラスでオーバーライドされると、インターネットリソースの非同期要求を開始します。

Public Overridable Function BeginGetResponse( _
   ByVal callback As AsyncCallback, _   ByVal state As Object _) As IAsyncResult
[C#]
public virtual IAsyncResult BeginGetResponse(AsyncCallbackcallback,objectstate);
[C++]
public: virtual IAsyncResult* BeginGetResponse(AsyncCallback* callback,Object* state);
[JScript]
public function BeginGetResponse(
   callback : AsyncCallback,state : Object) : IAsyncResult;

パラメータ

callback
AsyncCallback デリゲート。
state
非同期要求の状態情報を格納するオブジェクト。

戻り値

非同期の要求を参照する IAsyncResult 。

例外

例外の種類	条件
NotSupportedException	メソッドが派生クラスでオーバーライドされていないのに、そのメソッドへのアクセスが試行されました。

解説

BeginGetResponse メソッドは、応答の非同期要求を開始します。 AsyncCallback デリゲートを実装するコールバックメソッドは、 EndGetResponse メソッドを使用してインターネットリソースから WebResponse を返します。

メモ WebRequest クラスは、抽象 (Visual Basic では MustInherit) クラスです。実行時の WebRequest インスタンスの実際の動作は、 WebRequest.Create メソッドで返される派生クラスによって決まります。既定値および例外の詳細については、 HttpWebRequest や FileWebRequest などの派生クラスの説明を参照してください。

使用例

[Visual Basic, C#, C++] BeginGetResponse を使用して、ターゲットリソースを非同期的に要求する例を次に示します。リソースが取得されている場合は、指定したコールバックメソッドが実行されます。

 

Imports System
Imports System.Net
Imports System.IO
Imports System.Text
Imports System.Threading
Imports Microsoft.VisualBasic



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 ' New
End Class ' RequestState

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("https://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 ' Main

  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 ' RespCallback
  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 ' ReadCallBack 

End Class ' WebRequest_BeginGetResponse


[C#] 

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("https://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);
    }

  }

}

[C++] 

#using <mscorlib.dll>
#using <System.dll>
using namespace System;
using namespace System::Net;
using namespace System::IO;
using namespace System::Text;
using namespace System::Threading;

public __gc class RequestState {
   // This class stores the state of the request.
   static const int BUFFER_SIZE = 1024;
public:
   StringBuilder*  requestData;
   Byte  bufferRead[];
   WebRequest*  request;
   WebResponse*  response;
   Stream*  responseStream;

   RequestState() {
      bufferRead = new Byte[BUFFER_SIZE];
      requestData = new StringBuilder(S"");
      request = 0;
      responseStream = 0;
   }
};

__gc class WebRequest_BeginGetResponse {
public:
   static ManualResetEvent* allDone = new ManualResetEvent(false);
   static const 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, new AsyncCallback(0, ReadCallBack), myRequestState);

      } catch (WebException* e) {
         Console::WriteLine(S"WebException raised!");
         Console::WriteLine(S"\n {0}", e->Message);
         Console::WriteLine(S"\n {0}", __box(e->Status));
      } catch (Exception* e) {
         Console::WriteLine(S"Exception raised!");
         Console::WriteLine(S"Source : {0}", e->Source);
         Console::WriteLine(S"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,
               new AsyncCallback(0, ReadCallBack), myRequestState);
         } else {
            Console::WriteLine(S"\nThe HTML page Contents are:  ");
            if (myRequestState->requestData->Length>1) {
               String* sringContent;
               sringContent = myRequestState->requestData->ToString();
               Console::WriteLine(sringContent);
            }
            Console::WriteLine(S"\nPress 'Enter' key to continue........");
            responseStream->Close();
            allDone->Set();
         }
      } catch (WebException* e) {
         Console::WriteLine(S"WebException raised!");
         Console::WriteLine(S"\n {0}", e->Message);
         Console::WriteLine(S"\n {0}", __box(e->Status));
      } catch (Exception* e) {
         Console::WriteLine(S"Exception raised!");
         Console::WriteLine(S"Source : {0}" , e->Source);
         Console::WriteLine(S"Message : {0}" , e->Message);
      }
   }
};

int main() {
   try {
      // Create a new webrequest to the mentioned URL.
      WebRequest* myWebRequest= WebRequest::Create(S"https://www.contoso.com");

      // Please, set the proxy to a correct value.
      WebProxy* proxy = new WebProxy(S"myproxy:80");
      proxy->Credentials = new NetworkCredential(S"srikun", S"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 =
         dynamic_cast<IAsyncResult*> (myWebRequest->BeginGetResponse(new AsyncCallback(asyncResult, WebRequest_BeginGetResponse::RespCallback), myRequestState));
      WebRequest_BeginGetResponse::allDone->WaitOne();
      // Release the WebResponse resource.
      myRequestState->response->Close();
      Console::Read();
   } catch (WebException* e) {
      Console::WriteLine(S"WebException raised!");
      Console::WriteLine(S"\n {0}", e->Message);
      Console::WriteLine(S"\n {0}", __box(e->Status));
   } catch (Exception* e) {
      Console::WriteLine(S"Exception raised!");
      Console::WriteLine(S"Source : {0}", e->Source);
      Console::WriteLine(S"Message : {0}", e->Message);
   }
}

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必要条件

プラットフォーム: Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 ファミリ, .NET Compact Framework - Windows CE .NET, Common Language Infrastructure (CLI) Standard

参照

次の方法で共有

WebRequest.BeginGetResponse メソッド

パラメータ

戻り値

例外

解説

使用例

必要条件

参照

その他のリソース