FtpWebRequest.BeginGetRequestStream(AsyncCallback, Object) 方法

定義

命名空間:

System.Net

組件:

System.Net.Requests.dll

來源:

FtpWebRequest.cs

開始非同步開啟要求的內容資料流，以進行寫入。

public:
 override IAsyncResult ^ BeginGetRequestStream(AsyncCallback ^ callback, System::Object ^ state);

public override IAsyncResult BeginGetRequestStream (AsyncCallback? callback, object? state);

override this.BeginGetRequestStream : AsyncCallback * obj -> IAsyncResult

Public Overrides Function BeginGetRequestStream (callback As AsyncCallback, state As Object) As IAsyncResult

參數

callback

AsyncCallback

AsyncCallback 委派，會於作業完成時參考要叫用的方法。

state

Object

使用者定義物件，包含作業的相關資訊。 作業完成時會將這個物件傳遞給 callback 委派。

傳回

IAsyncResult

IAsyncResult 執行個體，指出作業的狀態。

例外狀況

InvalidOperationException

對這個方法的上一個呼叫或 GetRequestStream() 尚未完成。

WebException

無法建立與 FTP 伺服器的連接。

ProtocolViolationException

Method 屬性未設定為 UploadFile。

範例

下列程式代碼範例示範如何開始異步操作，以取得要求的數據流。 此程式代碼範例是類別概觀所提供較大範例的 FtpWebRequest 一部分。

// Command line arguments are two strings:
// 1. The url that is the name of the file being uploaded to the server.
// 2. The name of the file on the local machine.
//
static void Main()
{
   array<String^>^args = Environment::GetCommandLineArgs();

   // Create a Uri instance with the specified URI string.
   // If the URI is not correctly formed, the Uri constructor
   // will throw an exception.
   ManualResetEvent^ waitObject;
   Uri^ target = gcnew Uri( args[ 1 ] );
   String^ fileName = args[ 2 ];
   FtpState^ state = gcnew FtpState;
   FtpWebRequest ^ request = dynamic_cast<FtpWebRequest^>(WebRequest::Create( target ));
   request->Method = WebRequestMethods::Ftp::UploadFile;

   // This example uses anonymous logon.
   // The request is anonymous by default; the credential does not have to be specified. 
   // The example specifies the credential only to
   // control how actions are logged on the server.
   request->Credentials = gcnew NetworkCredential( "anonymous","janeDoe@contoso.com" );

   // Store the request in the object that we pass into the
   // asynchronous operations.
   state->Request = request;
   state->FileName = fileName;

   // Get the event to wait on.
   waitObject = state->OperationComplete;

   // Asynchronously get the stream for the file contents.
   request->BeginGetRequestStream( gcnew AsyncCallback( EndGetStreamCallback ), state );

   // Block the current thread until all operations are complete.
   waitObject->WaitOne();

   // The operations either completed or threw an exception.
   if ( state->OperationException != nullptr )
   {
      throw state->OperationException;
   }
   else
   {
      Console::WriteLine( "The operation completed - {0}", state->StatusDescription );
   }
}

// Command line arguments are two strings:
// 1. The url that is the name of the file being uploaded to the server.
// 2. The name of the file on the local machine.
//
public static void Main(string[] args)
{
    // Create a Uri instance with the specified URI string.
    // If the URI is not correctly formed, the Uri constructor
    // will throw an exception.
    ManualResetEvent waitObject;

    Uri target = new Uri (args[0]);
    string fileName = args[1];
    FtpState state = new FtpState();
    FtpWebRequest request = (FtpWebRequest)WebRequest.Create(target);
    request.Method = WebRequestMethods.Ftp.UploadFile;

    // This example uses anonymous logon.
    // The request is anonymous by default; the credential does not have to be specified.
    // The example specifies the credential only to
    // control how actions are logged on the server.

    request.Credentials = new NetworkCredential ("anonymous","janeDoe@contoso.com");

    // Store the request in the object that we pass into the
    // asynchronous operations.
    state.Request = request;
    state.FileName = fileName;

    // Get the event to wait on.
    waitObject = state.OperationComplete;

    // Asynchronously get the stream for the file contents.
    request.BeginGetRequestStream(
        new AsyncCallback (EndGetStreamCallback),
        state
    );

    // Block the current thread until all operations are complete.
    waitObject.WaitOne();

    // The operations either completed or threw an exception.
    if (state.OperationException != null)
    {
        throw state.OperationException;
    }
    else
    {
        Console.WriteLine("The operation completed - {0}", state.StatusDescription);
    }
}

備註

您必須呼叫 EndGetRequestStream 方法來完成異步操作。 一般而言， EndGetRequestStream 是由所參考的方法呼叫 callback。 若要判斷作業的狀態，請檢查此方法所傳回之 物件中的 IAsyncResult 屬性。

此方法不會在等候數據流時封鎖。 若要封鎖，請呼叫 GetRequestStream 取代這個方法。

如需使用異步程序設計模型的詳細資訊，請參閱 異步呼叫同步方法。

注意

在應用程式中啟用網路追蹤時，這個成員會輸出追蹤資訊。 如需詳細資訊，請參閱 .NET Framework 中的網路追蹤。

給呼叫者的注意事項

此方法會產生網路流量。

另請參閱

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