UdpClient.BeginReceive(AsyncCallback, Object) Método
Definição
Recebe um datagrama de um host remoto de forma assíncrona.Receives a datagram from a remote host asynchronously.
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
Parâmetros
- requestCallback
- AsyncCallback
Um delegado AsyncCallback que faz referência ao método a ser invocado quando a operação é concluída.An AsyncCallback delegate that references the method to invoke when the operation is complete.
- state
- Object
Um objeto definido pelo usuário que contém informações sobre a operação de recebimento.A user-defined object that contains information about the receive operation. Esse objeto é passado para o delegado requestCallback quando a operação é concluída.This object is passed to the requestCallback delegate when the operation is complete.
Retornos
Um objeto IAsyncResult que referencia o recebimento assíncrono.An IAsyncResult object that references the asynchronous receive.
Exemplos
O exemplo de código a seguir usa BeginReceive para receber uma resposta do servidor de forma assíncrona.The following code example uses BeginReceive to asynchronously receive a server response.
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);
}
}
Comentários
A operação assíncrona BeginReceive deve ser concluída chamando o EndReceive método.The asynchronous BeginReceive operation must be completed by calling the EndReceive method. Normalmente, o método é invocado pelo requestCallback delegado.Typically, the method is invoked by the requestCallback delegate.
Este método não é bloqueado até que a operação seja concluída.This method does not block until the operation is complete. Para bloquear até que a operação seja concluída, use o Receive método.To block until the operation is complete, use the Receive method.
Para obter informações detalhadas sobre como usar o modelo de programação assíncrona, consulte chamando métodos síncronos de formaassíncrona.For detailed information about using the asynchronous programming model, see Calling Synchronous Methods Asynchronously.