UdpClient語法FromAsync

Question

對c＃和任務來說很新...試圖找到將UDPclient包裝到FromAsync（...）中的正確語法，似乎我錯過了一些參數...（不能使用ReceiveAsync，因爲它應該工作與 .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

我不認爲你可以使用FromAsync因爲UdpClient.EndReceive採取ref參數，這使得它與FromAsync的所有重載不兼容。儘管如此，您可以製作自己的擴展方法：

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; 
}