使用Receive（同步阻塞方式）, 注意使用同步方法时，需要使用线程来开始方法，不然会使UI界面卡死

            IPEndPoint RemoteIpEndPoint = new IPEndPoint(IPAddress.Any, 5858);
            UdpClient udpClient = new UdpClient(RemoteIpEndPoint);
            while (true) //由于Receive方法是阻塞方法，一个Receive操作完了后才能继续往下执行，所以能在这里使用死循环
                Byte[] receiveBytes = udpClient.Receive(ref RemoteIpEndPoint);
                string msg = Encoding.UTF8.GetString(receiveBytes);
使用BeginReceive（异步）
               private static void InitializeUdpClient()
              {               
                IPEndPoint RemoteIpEndPoint = new IPEndPoint(IPAddress.Any, 5858);
                UdpClient udpClient = new UdpClient(RemoteIpEndPoint);
                //如果这里写while(true) 则会不停挂起异步接收操作，直到占满缓冲区间或队列。会报“由于系统缓冲区空间不足或队列已满，不能执行套接字上的操作”的错
                UdpState s = new UdpState(udpClient, RemoteIpEndPoint);
                udpClient.BeginReceive(EndReceive, s);
        private static void EndReceive(IAsyncResult ar)
                UdpState s = ar.AsyncState as UdpState;
                if (s != null)
                    UdpClient udpClient = s.UdpClient;
                    IPEndPoint ip = s.IP;
                    Byte[] receiveBytes = udpClient.EndReceive(ar, ref ip);
                    string msg = Encoding.UTF8.GetString(receiveBytes);
                    udpClient.BeginReceive(EndReceive, s);//在这里重新开始一个异步接收，用于处理下一个网络请求
            catch (Exception ex)
                //处理异常
    public class UdpState
        private UdpClient udpclient = null;
        public UdpClient UdpClient
            get { return udpclient; }
        private IPEndPoint ip;
        public IPEndPoint IP
            get { return ip; }
        public UdpState(UdpClient udpclient, IPEndPoint ip)
            this.udpclient = udpclient;
            this.ip = ip;