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FileWebRequest.BeginGetResponse Method

Begins an asynchronous request for a file system resource.

Namespace: System.Net
Assembly: System (in system.dll)

public override IAsyncResult BeginGetResponse (
	AsyncCallback callback,
	Object state
)
public IAsyncResult BeginGetResponse (
	AsyncCallback callback, 
	Object state
)
public override function BeginGetResponse (
	callback : AsyncCallback, 
	state : Object
) : IAsyncResult
Not applicable.

Parameters

callback

The AsyncCallback delegate.

state

An object that contains state information for this request.

Return Value

An IAsyncResult that references the asynchronous request.

Exception typeCondition

InvalidOperationException

The stream is already in use by a previous call to BeginGetResponse.

The asynchronous callback method that implements the AsyncCallback delegate uses the EndGetResponse method to return the actual FileWebResponse.

The following code example uses the BeginGetResponse method to asynchronously access a file system resource.


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 FileWebRequest myFileWebRequest;

    public RequestDeclare()
    {
        myFileWebRequest = null;
    } //RequestDeclare
} //RequestDeclare

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

    public 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.get_Message());
            }
            catch (UriFormatException e) {
                Console.WriteLine("UriFormatException is :" 
                    + e.get_Message());
            }
        }
    } //main

    private static void RespCallback(IAsyncResult ar)
    {
        // State of request is asynchronous.
        RequestDeclare requestDeclare = (RequestDeclare)(ar.
            get_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.");
    } //RespCallback
} //FileWebRequestResBeginEnd 

Windows 98, Windows Server 2000 SP4, Windows Millennium Edition, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0, 1.1, 1.0

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