UdpClient.BeginReceive(AsyncCallback, Object) Метод

public:
 IAsyncResult ^ BeginReceive(AsyncCallback ^ requestCallback, System::Object ^ state);

public IAsyncResult BeginReceive (AsyncCallback? requestCallback, object? state);

public IAsyncResult BeginReceive (AsyncCallback requestCallback, object state);

member this.BeginReceive : AsyncCallback * obj -> IAsyncResult

Public Function BeginReceive (requestCallback As AsyncCallback, state As Object) As IAsyncResult

Параметры

Возвращаемое значение

Объект IAsyncResult, который ссылается на асинхронный прием.

Примеры

В следующем примере кода используется BeginReceive для асинхронного получения ответа сервера.

private:
    static int listenPort = 13000;

public:
    value struct UdpState
    {
    public:
        UdpClient^ udpClient;
        IPEndPoint^ ipEndPoint;
    };

    static bool isMessageReceived;

    static void ReceiveCallback(IAsyncResult^ asyncResult)
    {
        UdpClient^ udpClient =
            ((UdpState)(asyncResult->AsyncState)).udpClient;
        IPEndPoint^ ipEndPoint =
            ((UdpState)(asyncResult->AsyncState)).ipEndPoint;

        array<Byte>^ receiveBytes =
            udpClient->EndReceive(asyncResult, ipEndPoint);
        String^ receiveString =
            Encoding::ASCII->GetString(receiveBytes);

        Console::WriteLine("Received: {0}", receiveString);
        isMessageReceived = true;
    }

    static void ReceiveMessages()
    {
        // Receive a message and write it to the console.
        IPEndPoint^ ipEndPoint = gcnew IPEndPoint(IPAddress::Any, listenPort);
        UdpClient^ udpClient = gcnew UdpClient(ipEndPoint);

        UdpState^ udpState = gcnew UdpState();
        udpState->ipEndPoint = ipEndPoint;
        udpState->udpClient = udpClient;

        Console::WriteLine("listening for messages");
        udpClient->BeginReceive(gcnew AsyncCallback(ReceiveCallback),
            udpState);

        // Do some work while we wait for a message. For this example,
        // we'll just sleep
        while (!isMessageReceived)
        {
            Thread::Sleep(100);
        }
    }

public struct UdpState
{
    public UdpClient u;
    public IPEndPoint e;
}

public static bool messageReceived = false;

public static void ReceiveCallback(IAsyncResult ar)
{
    UdpClient u = ((UdpState)(ar.AsyncState)).u;
    IPEndPoint e = ((UdpState)(ar.AsyncState)).e;

    byte[] receiveBytes = u.EndReceive(ar, ref e);
    string receiveString = Encoding.ASCII.GetString(receiveBytes);

    Console.WriteLine($"Received: {receiveString}");
    messageReceived = true;
}

public static void ReceiveMessages()
{
    // Receive a message and write it to the console.
    IPEndPoint e = new IPEndPoint(IPAddress.Any, s_listenPort);
    UdpClient u = new UdpClient(e);

    UdpState s = new UdpState();
    s.e = e;
    s.u = u;

    Console.WriteLine("listening for messages");
    u.BeginReceive(new AsyncCallback(ReceiveCallback), s);

    // Do some work while we wait for a message. For this example, we'll just sleep
    while (!messageReceived)
    {
        Thread.Sleep(100);
    }
}

Комментарии

Асинхронная BeginReceive операция должна быть завершена путем вызова EndReceive метода . Как правило, метод вызывается делегатом requestCallback .

Этот метод не блокируется до завершения операции. Чтобы заблокировать до завершения операции, используйте Receive метод .

Подробные сведения об использовании асинхронной модели программирования см. в разделе Асинхронный вызов синхронных методов.

Применяется к