語言

UdpClient.BeginReceive(AsyncCallback, Object) 方法

定義

命名空間:
System.Net.Sockets
組件:
netstandard.dll, System.Net.Sockets.dll
組件:
System.Net.Sockets.dll
組件:
System.dll
組件:
netstandard.dll
來源:
UDPClient.cs
來源:
UDPClient.cs
來源:
UDPClient.cs
來源:
UDPClient.cs
來源:
UDPClient.cs

非同步接收來自遠端主機的資料報。

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

參數

requestCallback
AsyncCallback

一個 AsyncCallback 代理，當操作完成時會參考呼叫的方法。

state
Object

一個由使用者定義的物件，包含接收操作的資訊。 當操作完成時，這個物件會傳給 requestCallback 代理。

傳回

IAsyncResult

一個 IAsyncResult 參考非同步接收的物件。

範例

以下程式碼範例用於 BeginReceive 非同步接收伺服器回應。

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);
    }
}

備註

非同步 BeginReceive 操作必須透過呼叫該 EndReceive 方法來完成。 通常，該方法由 requestCallback 委託人執行。

此方法在操作完成前不會阻塞。 要阻擋直到操作完成，請使用該 Receive 方法。

關於使用非同步程式設計模型的詳細資訊，請參見 「非同步呼叫同步方法」。

適用於