FtpWebRequest.Abort 方法

定义

命名空间:

System.Net

程序集:

System.Net.Requests.dll

Source:

FtpWebRequest.cs

终止异步 FTP 操作。

public:
 override void Abort();

public override void Abort ();

override this.Abort : unit -> unit

Public Overrides Sub Abort ()

示例

下面的代码示例演示了用户如何终止将文件从本地目录异步上传到服务器。

public:
   void AbortUpload( String^ fileName, String^ serverUri )
   {
      request = dynamic_cast<FtpWebRequest^>(WebRequest::Create( serverUri ));
      request->Method = WebRequestMethods::Ftp::UploadFile;

      // Get the file to be uploaded and convert it to bytes.
      StreamReader^ sourceStream = gcnew StreamReader( fileName );
      fileContents = Encoding::UTF8->GetBytes( sourceStream->ReadToEnd() );
      sourceStream->Close();

      // Set the content length to the number of bytes in the file.
      request->ContentLength = fileContents->Length;

      // Asynchronously get the stream for the file contents.
      IAsyncResult^ ar = request->BeginGetRequestStream( gcnew AsyncCallback( this, &AsynchronousFtpUpLoader::EndGetStreamCallback ), nullptr );
      Console::WriteLine( "Getting the request stream asynchronously..." );
      Console::WriteLine( "Press 'a' to abort the upload or any other key to continue" );
      String^ input = Console::ReadLine();
      if ( input->Equals( "a" ) )
      {
         request->Abort();
         Console::WriteLine( "Request aborted" );
         return;
      }
   }

public class ApplicationMain
{
    public static void Main()
    {
          ManualResetEvent wait = new ManualResetEvent(false);
          AsynchronousFtpUpLoader uploader = new AsynchronousFtpUpLoader(wait);
          uploader.AllowAbortUpload("out.txt", "ftp://sharriso1/ftptests.txt");
          wait.WaitOne();
          if (uploader.AsyncException != null)
          {
                Console.WriteLine(uploader.AsyncException.ToString());
          }
    }
}
    public class AsynchronousFtpUpLoader
    {
        ManualResetEvent wait;
        FtpWebRequest request;
        byte [] fileContents;
        Exception asyncException = null;

        public AsynchronousFtpUpLoader(ManualResetEvent wait)
        {
            this.wait = wait;
        }

        public Exception AsyncException
        {
            get { return asyncException;}
        }

        private void EndGetStreamCallback(IAsyncResult ar)
        {
            Stream requestStream = null;
            // End the asynchronous call to get the request stream.
            try
            {
                requestStream = request.EndGetRequestStream(ar);
            }
            // Return exceptions to the main application thread.
            catch (Exception e)
            {
                Console.WriteLine("Could not get the request stream.");
                asyncException = e;
                wait.Set();
                return;
            }
            // Write the file contents to the request stream.
            requestStream.Write(fileContents, 0, fileContents.Length);
            Console.WriteLine ("Writing {0} bytes to the stream.", fileContents.Length);
            // IMPORTANT: Close the request stream before sending the request.
            requestStream.Close();
        }

        // The EndGetResponseCallback method
        // completes a call to BeginGetResponse.
        private void EndGetResponseCallback(IAsyncResult ar)
        {
            FtpWebResponse response = null;
            try
            {
                response = (FtpWebResponse) request.EndGetResponse(ar);
            }
            // Return exceptions to the main application thread.
            catch (Exception e)
            {
                Console.WriteLine ("Error getting response.");
                asyncException = e;
                wait.Set();
            }
            Console.WriteLine("Upload status: {0}",response.StatusDescription);
            // Signal the application thread that this operation is complete.
            wait.Set();
        }
        internal void AbortRequest(FtpWebRequest request)
        {
            request.Abort();
            Console.WriteLine("Request aborted!");
            wait.Set();
        }

       public void AllowAbortUpload(string fileName, string serverUri)
       {
            request = (FtpWebRequest)WebRequest.Create(serverUri);
            request.Method = WebRequestMethods.Ftp.UploadFile;
            // Get the file to be uploaded and convert it to bytes.
            StreamReader sourceStream = new StreamReader(fileName);
            fileContents = Encoding.UTF8.GetBytes(sourceStream.ReadToEnd());
            sourceStream.Close();
            // Set the content length to the number of bytes in the file.
            request.ContentLength = fileContents.Length;
            // Asynchronously get the stream for the file contents.
            IAsyncResult ar = request.BeginGetRequestStream(
                new AsyncCallback (EndGetStreamCallback), null);
             while (!ar.IsCompleted)
            {
                Console.WriteLine("Press 'a' to abort writing to the request stream. Press any other key to continue...");
                string input = Console.ReadLine();
                if (input == "a")
                {
                    AbortRequest(request);
                    return;
                }
            }
            Console.WriteLine("Sending the request asynchronously...");
            IAsyncResult responseAR = request.BeginGetResponse(
                new AsyncCallback (EndGetResponseCallback), null);

            while (!responseAR.IsCompleted)
            {
                Console.WriteLine("Press 'a' to abort the upload. Press any other key to continue.");
                string input = Console.ReadLine();
                if (input == "a")
                {
                    AbortRequest(request);
                    return;
                }
            }
        }

注解

如果没有正在进行的操作，此方法不执行任何操作。 如果正在进行文件传输，此方法将终止传输。

备注

当你在应用程序中启用网络跟踪后，此成员将输出跟踪信息。 有关详细信息，请参阅 .NET Framework 中的网络跟踪。

另请参阅

• FtpWebResponse
• FtpStatusCode
• WebRequestMethods.Ftp
• WebRequest
• WebResponse
• WebClient