FtpWebRequest.UsePassive 屬性

  • 參考

定義

命名空間:
System.Net
組件:
System.Net.Requests.dll
組件:
System.dll
組件:
netstandard.dll
來源:
FtpWebRequest.cs
來源:
FtpWebRequest.cs
來源:
FtpWebRequest.cs

取得或設定用戶端應用程式之資料傳輸處理序的行為。

public:
 property bool UsePassive { bool get(); void set(bool value); };
public bool UsePassive { get; set; }
member this.UsePassive : bool with get, set
Public Property UsePassive As Boolean

屬性值

Boolean

如果用戶端應用程式的資料傳輸處理序會接聽資料連接埠上的連接，則為 false；如果用戶端應該在資料連接埠上啟始連接，則為 true。 預設值是 true。

例外狀況

InvalidOperationException

由於已經在進行的要求，已為這個屬性指定新的值。

範例

下列程式碼範例會擷取並顯示指定 FtpWebRequest 物件的屬性值。

private:
   // DisplayRequestProperties prints a request's properties.
   // This method should be called after the request is sent to the server.
   static void DisplayRequestProperties( FtpWebRequest^ request )
   {
      Console::WriteLine( "User {0} {1}", request->Credentials->GetCredential( request->RequestUri, "basic" )->UserName, request->RequestUri );

      Console::WriteLine( "Request: {0} {1}", request->Method, request->RequestUri );

      Console::WriteLine( "Passive: {0}  Keep alive: {1}  Binary: {2} Timeout: {3}.", request->UsePassive, request->KeepAlive, request->UseBinary, request->Timeout == -1 ? "none" : request->Timeout.ToString() );

      IWebProxy^ proxy = request->Proxy;
      if ( proxy )
      {
         Console::WriteLine( "Proxy: {0}", proxy->GetProxy( request->RequestUri ) );
      }
      else
      {
         Console::WriteLine( "Proxy: (none)" );
      }

      Console::WriteLine( "ConnectionGroup: {0}", request->ConnectionGroupName == nullptr ? "none" : request->ConnectionGroupName );

      Console::WriteLine( "Encrypted connection: {0}", request->EnableSsl );

      Console::WriteLine("Method: {0}", request->Method);
   }

// DisplayRequestProperties prints a request's properties.
// This method should be called after the request is sent to the server.

private static void DisplayRequestProperties(FtpWebRequest request)
{
    Console.WriteLine("User {0} {1}",
        request.Credentials.GetCredential(request.RequestUri,"basic").UserName,
        request.RequestUri
    );
    Console.WriteLine("Request: {0} {1}",
        request.Method,
        request.RequestUri
    );
    Console.WriteLine("Passive: {0}  Keep alive: {1}  Binary: {2} Timeout: {3}.",
        request.UsePassive,
        request.KeepAlive,
        request.UseBinary,
        request.Timeout == -1 ? "none" : request.Timeout.ToString()
    );
    IWebProxy proxy = request.Proxy;
    if (proxy != null)
    {
        Console.WriteLine("Proxy: {0}", proxy.GetProxy(request.RequestUri));
    }
    else
    {
        Console.WriteLine("Proxy: (none)");
    }

    Console.WriteLine("ConnectionGroup: {0}",
        request.ConnectionGroupName == null ? "none" : request.ConnectionGroupName
    );

    Console.WriteLine("Encrypted connection: {0}",
        request.EnableSsl);

    Console.WriteLine("Method: {0}", request.Method);
}

備註

UsePassive將 屬性設定為 true 將 「 PASV" 命令傳送至伺服器。 此命令會要求伺服器接聽資料埠，並等候連線，而不是在收到傳輸命令時起始連線。

如需使用 UsePassive 所指定行為的描述，請參閱 RFC 959：「檔案傳輸通訊協定」，第 3.2 節：「建立資料連線」和第 4.1.2 節：「傳輸參數命令」。

呼叫 、 、 或 方法之後變更 UsePassive 會導致 InvalidOperationException 例外狀況。 BeginGetResponseGetResponseBeginGetRequestStreamGetRequestStream

如果 UsePassive 設定為 true ，FTP 伺服器可能不會傳送檔案的大小，而且下載進度一律可以是零。 如果 UsePassive 設定為 false ，防火牆可以引發警示並封鎖檔案下載。

適用於

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