FileWebRequest::BeginGetRequestStream Method (AsyncCallback^, Object^)
.NET Framework (current version)
Begins an asynchronous request for a Stream object to use to write data.
Assembly: System (in System.dll)
public: [HostProtectionAttribute(SecurityAction::LinkDemand, ExternalThreading = true)] virtual IAsyncResult^ BeginGetRequestStream( AsyncCallback^ callback, Object^ state ) override
Parameters
- callback
-
Type:
System::AsyncCallback^
The AsyncCallback delegate.
- state
-
Type:
System::Object^
An object that contains state information for this request.
| Exception | Condition |
|---|---|
| ProtocolViolationException | The Method property is GET and the application writes to the stream. |
| InvalidOperationException | The stream is being used by a previous call to BeginGetRequestStream. |
| ApplicationException | No write stream is available. |
| WebException | The FileWebRequest was aborted. |
The BeginGetRequestStream method starts an asynchronous request for a stream used to send data to a file system resource. The callback method that implements the AsyncCallback delegate uses the EndGetRequestStream method to return the request stream.
The following code example uses BeginGetRequestStream to make an asynchronous request for a Stream object.
public ref class RequestDeclare { public: FileWebRequest^ myFileWebRequest; String^ userinput; RequestDeclare() { myFileWebRequest = nullptr; } }; ref class FileWebRequest_reqbeginend { public: static ManualResetEvent^ allDone = gcnew ManualResetEvent( false ); static void ReadCallback( IAsyncResult^ ar ) { try { // State of the request is asynchronous. RequestDeclare^ requestDeclare = dynamic_cast<RequestDeclare^>(ar->AsyncState); FileWebRequest^ myFileWebRequest = requestDeclare->myFileWebRequest; String^ sendToFile = requestDeclare->userinput; // End the Asynchronus request by calling the 'EndGetRequestStream()' method. Stream^ readStream = myFileWebRequest->EndGetRequestStream( ar ); // Convert the String* into Byte array. ASCIIEncoding^ encoder = gcnew ASCIIEncoding; array<Byte>^byteArray = encoder->GetBytes( sendToFile ); // Write to the stream. readStream->Write( byteArray, 0, sendToFile->Length ); readStream->Close(); allDone->Set(); Console::WriteLine( "\nThe String you entered was successfully written into the file." ); Console::WriteLine( "\nPress Enter to continue." ); } catch ( ApplicationException^ e ) { Console::WriteLine( "ApplicationException is : {0}", e->Message ); } } }; 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_reqbeginend <systemname>/<sharedfoldername>/<filename>\n" ); Console::WriteLine( "Example:FileWebRequest_reqbeginend 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 associate the 'myWebRequest' to it. RequestDeclare^ requestDeclare = gcnew RequestDeclare; requestDeclare->myFileWebRequest = dynamic_cast<FileWebRequest^>(myWebRequest); // Set the 'Method' property of 'FileWebRequest' Object* to 'POST' method. requestDeclare->myFileWebRequest->Method = "POST"; Console::WriteLine( "Enter the String* you want to write into the file:" ); requestDeclare->userinput = Console::ReadLine(); // Begin the Asynchronous request for getting file content using 'BeginGetRequestStream()' method . IAsyncResult^ r = dynamic_cast<IAsyncResult^>(requestDeclare->myFileWebRequest->BeginGetRequestStream( gcnew AsyncCallback( &FileWebRequest_reqbeginend::ReadCallback ), requestDeclare )); FileWebRequest_reqbeginend::allDone->WaitOne(); Console::Read(); } catch ( ProtocolViolationException^ e ) { Console::WriteLine( "ProtocolViolationException is : {0}", e->Message ); } catch ( InvalidOperationException^ e ) { Console::WriteLine( "InvalidOperationException is : {0}", e->Message ); } catch ( UriFormatException^ e ) { Console::WriteLine( "UriFormatExceptionException is : {0}", e->Message ); } } }
.NET Framework
Available since 1.1
Available since 1.1
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