FtpWebRequest.EndGetRequestStream(IAsyncResult) 方法

定义

命名空间:

System.Net

程序集:

System.Net.Requests.dll

Source:

FtpWebRequest.cs

结束由 BeginGetRequestStream(AsyncCallback, Object) 启动的挂起的异步操作。

public:
 override System::IO::Stream ^ EndGetRequestStream(IAsyncResult ^ asyncResult);

public override System.IO.Stream EndGetRequestStream (IAsyncResult asyncResult);

override this.EndGetRequestStream : IAsyncResult -> System.IO.Stream

Public Overrides Function EndGetRequestStream (asyncResult As IAsyncResult) As Stream

参数

asyncResult

IAsyncResult

在操作开始时返回的 IAsyncResult 对象。

返回

Stream

与此实例关联的可写 Stream 实例。

例外

ArgumentNullException

asyncResult 为 null。

ArgumentException

未能通过调用 BeginGetRequestStream(AsyncCallback, Object) 获取 asyncResult。

InvalidOperationException

已为 asyncResult 标识的操作调用了此方法。

示例

下面的代码示例演示如何结束异步操作以获取请求的流。 此代码示例是为类概述提供的更大示例的 FtpWebRequest 一部分。

private:
   static void EndGetStreamCallback( IAsyncResult^ ar )
   {
      FtpState^ state = dynamic_cast<FtpState^>(ar->AsyncState);
      Stream^ requestStream = nullptr;

      // End the asynchronous call to get the request stream.
      try
      {
         requestStream = state->Request->EndGetRequestStream( ar );

         // Copy the file contents to the request stream.
         const int bufferLength = 2048;
         array<Byte>^buffer = gcnew array<Byte>(bufferLength);
         int count = 0;
         int readBytes = 0;
         FileStream^ stream = File::OpenRead( state->FileName );
         do
         {
            readBytes = stream->Read( buffer, 0, bufferLength );
            requestStream->Write( buffer, 0, bufferLength );
            count += readBytes;
         }
         while ( readBytes != 0 );
         Console::WriteLine( "Writing {0} bytes to the stream.", count );

         // IMPORTANT: Close the request stream before sending the request.
         requestStream->Close();

         // Asynchronously get the response to the upload request.
         state->Request->BeginGetResponse( gcnew AsyncCallback( EndGetResponseCallback ), state );
      }
      // Return exceptions to the main application thread.
      catch ( Exception^ e ) 
      {
         Console::WriteLine( "Could not get the request stream." );
         state->OperationException = e;
         state->OperationComplete->Set();
         return;
      }
   }

private static void EndGetStreamCallback(IAsyncResult ar)
{
    FtpState state = (FtpState) ar.AsyncState;

    Stream requestStream = null;
    // End the asynchronous call to get the request stream.
    try
    {
        requestStream = state.Request.EndGetRequestStream(ar);
        // Copy the file contents to the request stream.
        const int bufferLength = 2048;
        byte[] buffer = new byte[bufferLength];
        int count = 0;
        int readBytes = 0;
        FileStream stream = File.OpenRead(state.FileName);
        do
        {
            readBytes = stream.Read(buffer, 0, bufferLength);
            requestStream.Write(buffer, 0, readBytes);
            count += readBytes;
        }
        while (readBytes != 0);
        Console.WriteLine ("Writing {0} bytes to the stream.", count);
        // IMPORTANT: Close the request stream before sending the request.
        requestStream.Close();
        // Asynchronously get the response to the upload request.
        state.Request.BeginGetResponse(
            new AsyncCallback (EndGetResponseCallback),
            state
        );
    }
    // Return exceptions to the main application thread.
    catch (Exception e)
    {
        Console.WriteLine("Could not get the request stream.");
        state.OperationException = e;
        state.OperationComplete.Set();
        return;
    }
}

注解

如果操作尚未完成，则 方法将 EndGetRequestStream 阻止，直到操作完成。 若要确定操作是否已完成，请在调用 EndGetRequestStream之前检查 IsCompleted 属性。

除了“异常” EndGetRequestStream 中记录的异常之外，还会重新引发在打开流进行写入时引发的异常。

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