NegotiateStream.BeginWrite 方法

定义

命名空间:

System.Net.Security

程序集:

System.Net.Security.dll

Source:

NegotiateStream.cs

开始一个异步写操作，此操作将指定缓冲区中的 Byte 写入到流中。

public:
 override IAsyncResult ^ BeginWrite(cli::array <System::Byte> ^ buffer, int offset, int count, AsyncCallback ^ asyncCallback, System::Object ^ asyncState);

public override IAsyncResult BeginWrite (byte[] buffer, int offset, int count, AsyncCallback? asyncCallback, object? asyncState);

override this.BeginWrite : byte[] * int * int * AsyncCallback * obj -> IAsyncResult

Public Overrides Function BeginWrite (buffer As Byte(), offset As Integer, count As Integer, asyncCallback As AsyncCallback, asyncState As Object) As IAsyncResult

参数

buffer

Byte[]

一个 Byte 数组，该数组提供要写入流中的字节。

offset

Int32

buffer 中从零开始的位置，从此处开始读取要写入到流中的字节。

count

Int32

Int32 值，该值指定要从 buffer 中读取的字节数。

asyncCallback

AsyncCallback

AsyncCallback 委托，它引用写操作完成时要调用的方法。

asyncState

Object

一个用户定义对象，其中包含写操作的相关信息。 操作完成时，此对象传递给 asyncCallback 委托。

返回

IAsyncResult

一个指示异步操作状态的 IAsyncResult 对象。

例外

ArgumentNullException

buffer 为 null。

ArgumentException

offset is less than 0.

- 或 -

offset 大于 buffer 的长度。

- 或 -

offset 加上计数大于 buffer 的长度。

IOException

写操作失败。

- 或 -

正在使用加密，但未能加密该数据。

NotSupportedException

已存在一个正在执行的写操作。

ObjectDisposedException

此对象已关闭。

InvalidOperationException

未进行身份验证。

示例

以下示例演示如何开始异步写入操作。

// Request authentication.
NetworkStream^ clientStream = client->GetStream();
NegotiateStream^ authStream = gcnew NegotiateStream( clientStream,false );

// Pass the NegotiateStream as the AsyncState object 
// so that it is available to the callback delegate.
IAsyncResult^ ar = authStream->BeginAuthenticateAsClient( gcnew AsyncCallback( EndAuthenticateCallback ), authStream );

Console::WriteLine( L"Client waiting for authentication..." );

// Wait until the result is available.
ar->AsyncWaitHandle->WaitOne();

// Display the properties of the authenticated stream.
AuthenticatedStreamReporter::DisplayProperties( authStream );

// Send a message to the server.
// Encode the test data into a byte array.
array<Byte>^message = Encoding::UTF8->GetBytes( L"Hello from the client." );
ar = authStream->BeginWrite( message, 0, message->Length, gcnew AsyncCallback( EndWriteCallback ), authStream );

// Request authentication.
NetworkStream clientStream = client.GetStream();
NegotiateStream authStream = new NegotiateStream(clientStream, false);
// Pass the NegotiateStream as the AsyncState object
// so that it is available to the callback delegate.
Task authenticateTask = authStream
    .AuthenticateAsClientAsync()
    .ContinueWith(task =>
    {
        Console.WriteLine("Client ending authentication...");
        Console.WriteLine("ImpersonationLevel: {0}", authStream.ImpersonationLevel);
    });

Console.WriteLine("Client waiting for authentication...");
// Wait until the result is available.
authenticateTask.Wait();
// Display the properties of the authenticated stream.
AuthenticatedStreamReporter.DisplayProperties(authStream);
// Send a message to the server.
// Encode the test data into a byte array.
byte[] message = Encoding.UTF8.GetBytes("Hello from the client.");
Task writeTask = authStream
    .WriteAsync(message, 0, message.Length)
    .ContinueWith(task =>
    {
        Console.WriteLine("Client ending write operation...");
    });

' Request authentication.
Dim clientStream = client.GetStream()
Dim authStream As New NegotiateStream(clientStream, False)

' Pass the NegotiateStream as the AsyncState object 
' so that it is available to the callback delegate.
Dim ar = authStream.BeginAuthenticateAsClient(
    New AsyncCallback(AddressOf EndAuthenticateCallback), authStream)

Console.WriteLine("Client waiting for authentication...")

' Wait until the result is available.
ar.AsyncWaitHandle.WaitOne()

' Display the properties of the authenticated stream.
AuthenticatedStreamReporter.DisplayProperties(authStream)

' Send a message to the server.
' Encode the test data into a byte array.
Dim message = Encoding.UTF8.GetBytes("Hello from the client.")
ar = authStream.BeginWrite(message, 0, message.Length, 
    New AsyncCallback(AddressOf EndWriteCallback), authStream)

操作完成后，将调用以下方法。

// The following method is called when the write operation completes.
static void EndWriteCallback( IAsyncResult^ ar )
{
   Console::WriteLine( L"Client ending write operation..." );
   NegotiateStream^ authStream = dynamic_cast<NegotiateStream^>(ar->AsyncState);
   
   // End the asynchronous operation.
   authStream->EndWrite( ar );
}

' The following method is called when the write operation completes.
Public Shared Sub EndWriteCallback(ar As IAsyncResult)

    Console.WriteLine("Client ending write operation...")
    Dim authStream = CType(ar.AsyncState, NegotiateStream)

    ' End the asynchronous operation.
    authStream.EndWrite(ar)

End Sub

注解

如果启用了加密、签名或加密和签名，则此方法从缓冲区读取数据，对数据进行加密、签名或加密和签名，并使用基础流传输数据。 如果未使用任何安全服务（如数据加密或签名），此方法将对基础流启动异步写入操作。

此方法是异步的，在操作完成时不会阻止。 若要在操作完成之前阻止，请使用 Read 方法。

异步读取操作必须通过调用 EndWrite 方法来完成。 通常，委托会调用 asyncCallback 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

类 NegotiateStream 不支持多个同时写入操作。 如果在另一个写入操作已在同一 NotSupportedException 流上执行时尝试启动写入操作，则会引发异常。

在成功进行身份验证之前，无法调用此方法。 若要进行身份验证，请调用 、、AuthenticateAsClientAsync、AuthenticateAsServerAsyncBeginAuthenticateAsClientAuthenticateAsServer、 或 BeginAuthenticateAsServer 方法之一。AuthenticateAsClient