FtpWebRequest.BeginGetRequestStream(AsyncCallback, Object) 方法

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

public override IAsyncResult BeginGetRequestStream(AsyncCallback? callback, 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

参数

返回

IAsyncResult 实例，指示操作的状态。

例外

示例

下面的代码示例演示如何启动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。

// 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);
    }
}

注解

必须通过调用 EndGetRequestStream 方法完成异步操作。 通常， EndGetRequestStream 由 引用 callback的方法调用。 若要确定操作的状态，请检查此方法返回的 IAsyncResult 对象中的属性。

此方法在等待流时不会阻止。 若要阻止，请调用 GetRequestStream 以代替此方法。

有关使用异步编程模型的详细信息，请参阅 异步调用同步方法。

调用方说明

此方法生成网络流量。

另请参阅

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