UdpClient.EndReceive(IAsyncResult, IPEndPoint) 方法

定義

命名空間:

System.Net.Sockets

組件:

System.Net.Sockets.dll

來源:

UDPClient.cs

結束暫止的非同步接收。

public:
 cli::array <System::Byte> ^ EndReceive(IAsyncResult ^ asyncResult, System::Net::IPEndPoint ^ % remoteEP);

public byte[] EndReceive (IAsyncResult asyncResult, ref System.Net.IPEndPoint? remoteEP);

member this.EndReceive : IAsyncResult * IPEndPoint -> byte[]

Public Function EndReceive (asyncResult As IAsyncResult, ByRef remoteEP As IPEndPoint) As Byte()

參數

asyncResult

IAsyncResult

IAsyncResult 物件，由對 BeginReceive(AsyncCallback, Object) 的呼叫傳回。

remoteEP

IPEndPoint

指定的遠端端點。

傳回

Byte[]

如果成功，即為包含資料包資料的位元組陣列。

例外狀況

ArgumentNullException

asyncResult 為 null。

ArgumentException

asyncResult 不會經由對 BeginReceive(AsyncCallback, Object) 方法的呼叫傳回。

InvalidOperationException

先前已針對非同步讀取呼叫 EndReceive(IAsyncResult, IPEndPoint)。

SocketException

嘗試存取基礎 Socket 時發生錯誤。

ObjectDisposedException

基礎 Socket 已關閉。

範例

下列程式代碼範例會使用 BeginSend 來完成伺服器回應的異步接收。

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);
    }
}

備註

這個方法會封鎖直到作業完成為止。

若要同步執行這項作業，請使用 Receive 方法。