UdpClient语法FromAsync

Question

对c#和任务非常陌生……试图找到正确的语法来将UDPclient封装到FromAsync(...)中，我似乎遗漏了一些参数...(不能使用ReceiveAsync，因为它应该适用于.NET 4.0)

public Task<byte[]> GetUDPmessageAsync()
{
    byte[] data = new byte[100];
    myUdpClient = new UdpClient(12000);

    Task<byte[]> task = Task<byte[]>.Factory.FromAsync(myUdpClient.BeginReceive, myUdpClient.EndReceive,?,?);
}

Answer 1

我不认为你可以使用FromAsync，因为UdpClient.EndReceive接受了一个ref参数，这使得它与FromAsync的所有重载都不兼容。不过，您可以创建自己的扩展方法：

public static Task<byte[]> ReceiveAsync(this UdpClient client, IPEndPoint endpoint)
{
    TaskCompletionSource<byte[]> tcs = new TaskCompletionSource<byte[]>();
    AsyncCallback callback = ar => {
        try
        {
            byte[] bytes = client.EndReceive(ar, ref endpoint);
            tcs.SetResult(bytes);
        }
        catch(Exception ex)
        {
            tcs.SetException(ex);
        }
    };
    client.BeginReceive(callback, null);
    return tcs.Task;
}