FileWebRequest.BeginGetResponse(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.
Startet eine asynchrone Anforderung einer Dateisystemressource.
public:
override IAsyncResult ^ BeginGetResponse(AsyncCallback ^ callback, System::Object ^ state);public override IAsyncResult BeginGetResponse (AsyncCallback? callback, object? state);public override IAsyncResult BeginGetResponse (AsyncCallback callback, object state);override this.BeginGetResponse : AsyncCallback * obj -> IAsyncResultPublic Overrides Function BeginGetResponse (callback As AsyncCallback, state As Object) As IAsyncResultParameter
- callback
- AsyncCallback
Der AsyncCallback -Delegat.
- state
- Object
Ein Objekt mit Zustandsinformationen für diese Anforderung.
Gibt zurück
Ein IAsyncResult, das auf die asynchrone Anforderung verweist.
Ausnahmen
Der Stream wird bereits von einem vorherigen Aufruf von BeginGetResponse(AsyncCallback, Object) verwendet.
Die FileWebRequest wurde abgebrochen.
Beispiele
Im folgenden Codebeispiel wird die BeginGetResponse Methode verwendet, um asynchron auf eine Dateisystemressource zuzugreifen.
public ref class RequestDeclare
{
public:
FileWebRequest^ myFileWebRequest;
RequestDeclare()
{
myFileWebRequest = nullptr;
}
};
ref class FileWebRequest_resbeginend
{
public:
static ManualResetEvent^ allDone = gcnew ManualResetEvent( false );
static void RespCallback( IAsyncResult^ ar )
{
// State of request is asynchronous.
RequestDeclare^ requestDeclare = dynamic_cast<RequestDeclare^>(ar->AsyncState);
FileWebRequest^ myFileWebRequest = requestDeclare->myFileWebRequest;
// End the Asynchronus request by calling the 'EndGetResponse()' method.
FileWebResponse^ myFileWebResponse = dynamic_cast<FileWebResponse^>(myFileWebRequest->EndGetResponse( ar ));
// Reade the response into Stream.
StreamReader^ streamReader = gcnew StreamReader( myFileWebResponse->GetResponseStream() );
array<Char>^readBuffer = gcnew array<Char>(256);
int count = streamReader->Read( readBuffer, 0, 256 );
Console::WriteLine( "The contents of the file are :\n" );
while ( count > 0 )
{
String^ str = gcnew String( readBuffer,0,count );
Console::WriteLine( str );
count = streamReader->Read( readBuffer, 0, 256 );
}
streamReader->Close();
// Release the response Object* resources.
myFileWebResponse->Close();
allDone->Set();
Console::WriteLine( "File reading is over." );
}
};
int main()
{
array<String^>^args = Environment::GetCommandLineArgs();
if ( args->Length < 2 )
{
Console::WriteLine( "\nPlease enter the file name as command line parameter:" );
Console::WriteLine( "Usage:FileWebRequest_resbeginend <systemname>/<sharedfoldername>/<filename>\n" );
Console::WriteLine( "Example:FileWebRequest_resbeginend shafeeque/shaf/hello.txt" );
}
else
{
try
{
// Place a 'Webrequest'.
WebRequest^ myWebRequest = WebRequest::Create( String::Concat( "file://", args[ 1 ] ) );
// Create an instance of the 'RequestDeclare' and associating the 'myWebRequest' to it.
RequestDeclare^ myRequestDeclare = gcnew RequestDeclare;
myRequestDeclare->myFileWebRequest = dynamic_cast<FileWebRequest^>(myWebRequest);
// Begin the Asynchronous request for getting file content using 'BeginGetResponse()' method.
IAsyncResult^ asyncResult = dynamic_cast<IAsyncResult^>(myRequestDeclare->myFileWebRequest->BeginGetResponse( gcnew AsyncCallback( &FileWebRequest_resbeginend::RespCallback ), myRequestDeclare ));
FileWebRequest_resbeginend::allDone->WaitOne();
}
catch ( ArgumentNullException^ e )
{
Console::WriteLine( "ArgumentNullException is : {0}", e->Message );
}
catch ( UriFormatException^ e )
{
Console::WriteLine( "UriFormatException is : {0}", e->Message );
}
}
}
public class RequestDeclare
{
public FileWebRequest myFileWebRequest;
public RequestDeclare()
{
myFileWebRequest = null;
}
}
class FileWebRequest_resbeginend
{
public static ManualResetEvent allDone = new ManualResetEvent(false);
static void Main(string[] args)
{
if (args.Length < 1)
{
Console.WriteLine("\nPlease enter the file name as command line parameter:");
Console.WriteLine("Usage:FileWebRequest_resbeginend <systemname>/<sharedfoldername>/<filename>\nExample:FileWebRequest_resbeginend shafeeque/shaf/hello.txt");
}
else
{
try
{
// Place a 'Webrequest'.
WebRequest myWebRequest= WebRequest.Create("file://"+args[0]);
// Create an instance of the 'RequestDeclare' and associating the 'myWebRequest' to it.
RequestDeclare myRequestDeclare = new RequestDeclare();
myRequestDeclare.myFileWebRequest = (FileWebRequest)myWebRequest;
// Begin the Asynchronous request for getting file content using 'BeginGetResponse()' method.
IAsyncResult asyncResult =(IAsyncResult) myRequestDeclare.myFileWebRequest.BeginGetResponse(new AsyncCallback(RespCallback),myRequestDeclare);
allDone.WaitOne();
}
catch(ArgumentNullException e)
{
Console.WriteLine("ArgumentNullException is :"+e.Message);
}
catch(UriFormatException e)
{
Console.WriteLine("UriFormatException is :"+e.Message);
}
}
}
private static void RespCallback(IAsyncResult ar)
{
// State of request is asynchronous.
RequestDeclare requestDeclare=(RequestDeclare) ar.AsyncState;
FileWebRequest myFileWebRequest=requestDeclare.myFileWebRequest;
// End the Asynchronus request by calling the 'EndGetResponse()' method.
FileWebResponse myFileWebResponse = (FileWebResponse) myFileWebRequest.EndGetResponse(ar);
// Reade the response into Stream.
StreamReader streamReader= new StreamReader(myFileWebResponse.GetResponseStream());
Char[] readBuffer = new Char[256];
int count = streamReader.Read( readBuffer, 0, 256 );
Console.WriteLine("The contents of the file are :\n");
while (count > 0)
{
String str = new String(readBuffer, 0, count);
Console.WriteLine(str);
count = streamReader.Read(readBuffer, 0, 256);
}
streamReader.Close();
// Release the response object resources.
myFileWebResponse.Close();
allDone.Set();
Console.WriteLine("File reading is over.");
}
}
Public Class RequestDeclare
Public myFileWebRequest As FileWebRequest
Public Sub New()
myFileWebRequest = Nothing
End Sub
End Class
Class FileWebRequest_resbeginend
Public Shared allDone As New ManualResetEvent(False)
' Entry point which delegates to C-style main Private Function.
Public Overloads Shared Sub Main()
Main(GetCommandLineArgs())
End Sub
Overloads Shared Sub Main(args() As String)
If args.Length < 2 Then
Console.WriteLine(ControlChars.Cr + "Please enter the file name as command line parameter:")
Console.WriteLine("Usage:FileWebRequest_resbeginend " + ChrW(60) + "systemname" + ChrW(62) + "/" + ChrW(60) + "sharedfoldername" + ChrW(62) + "/" + ChrW(60) + "filename" + ChrW(62) + ControlChars.Cr + "Example:FileWebRequest_resbeginend shafeeque/shaf/hello.txt")
Else
Try
' Place a webrequest.
Dim myWebRequest As WebRequest = WebRequest.Create(("file://" + args(1)))
' Create an instance of the 'RequestDeclare' and associating the 'myWebRequest' to it.
Dim myRequestDeclare As New RequestDeclare()
myRequestDeclare.myFileWebRequest = CType(myWebRequest, FileWebRequest)
' Begin the Asynchronous request for getting file content using 'BeginGetResponse()' method.
Dim asyncResult As IAsyncResult = CType(myRequestDeclare.myFileWebRequest.BeginGetResponse(AddressOf RespCallback, myRequestDeclare), IAsyncResult)
allDone.WaitOne()
Catch e As ArgumentNullException
Console.WriteLine(("ArgumentNullException is :" + e.Message))
Catch e As UriFormatException
Console.WriteLine(("UriFormatException is :" + e.Message))
End Try
End If
End Sub
Private Shared Sub RespCallback(ar As IAsyncResult)
' State of request is asynchronous.
Dim requestDeclare As RequestDeclare = CType(ar.AsyncState, RequestDeclare)
Dim myFileWebRequest As FileWebRequest = requestDeclare.myFileWebRequest
' End the Asynchronus request by calling the 'EndGetResponse()' method.
Dim myFileWebResponse As FileWebResponse = CType(myFileWebRequest.EndGetResponse(ar), FileWebResponse)
' Reade the response into Stream.
Dim streamReader As New StreamReader(myFileWebResponse.GetResponseStream())
Dim readBuffer(256) As [Char]
Dim count As Integer = streamReader.Read(readBuffer, 0, 256)
Console.WriteLine("The contents of the file are :"+ControlChars.Cr)
While count > 0
Dim str As New [String](readBuffer, 0, count)
Console.WriteLine(str)
count = streamReader.Read(readBuffer, 0, 256)
End While
streamReader.Close()
' Release the response object resources.
myFileWebResponse.Close()
allDone.Set()
Console.WriteLine("File reading is over.")
End Sub
End Class
Hinweise
Die asynchrone Rückrufmethode, die die AsyncCallback Stellvertretung implementiert, verwendet die EndGetResponse Methode, um den tatsächlichen FileWebResponseWert zurückzugeben.