udp 监听/接收 问题！！！！【在线】

Question

如果客户端设置监听6000端口的话，服务器端应该发送到客户端6000端口，服务器端收到的客户端请求的端口号之所以不同是因为初始化socket的时候没有进行端口绑定，系统会随机分配一个端口号给程序。

Answer 1

正解    public class UDPSocketService
    {        //private  static Socket          ServerSocketSender;
        private static int ServerUDPPortSend = 6790; // 
        private static Socket ServerSocketReceiver;
        private static AsyncCallback UDPReceiveCallback;             //udp回调函数 
        private static byte[] dataBuffers;                    //udp字节缓存  
        private static EndPoint ServerEndPoint;
        private static IPAddress svrIPAddress;        public static IPAddress ServerIPAddress
        {
            get { return UDPSocketService.svrIPAddress; }
            set { UDPSocketService.svrIPAddress = value; }
        }
        private static int svrUDPPortReceive = 9051; //          internal static int ServerUDPPortReceive
        {
            get { return UDPSocketService.svrUDPPortReceive; }
            set { UDPSocketService.svrUDPPortReceive = value; }
        }
        ///// <summary>
        ///// 取安装本软件的服务器ip
        ///// </summary>
        ///// <returns></returns>
        //public static IPAddress GetLocalIP()
        //{
        //    IPHostEntry iphostentry = Dns.GetHostByName(Dns.GetHostName());
        //    IPAddress HostIP = null;
        //    if (iphostentry.AddressList.Length > 0)
        //    { HostIP = iphostentry.AddressList[0]; }
        //    return HostIP;
        //}
        public static void UDPDataSend(byte[] data)
        {
            try
            {                Socket ServerSocketSender = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
                IPEndPoint iepBroadcast = new IPEndPoint(IPAddress.Broadcast, ServerUDPPortSend);//255.255.255.255                ServerSocketSender.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.Broadcast, 1);
                ServerSocketSender.SendTo(data, iepBroadcast);  //An operation was attempted on something that is not a socket
                ServerSocketSender.Close();
            }
            catch (Exception se)
            {
                BizLogic.LogWriter.AddSystemException(se);
            }        }
        public static void UDPDataSendTo(byte[] data, string IPAdd)
        {
            try
            {
                if (string.IsNullOrEmpty (IPAdd) == true  || IPAdd == "N/A")
                { return; }
                Socket ServerSocketSender = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
                IPEndPoint iepBroadcast = new IPEndPoint(IPAddress.Parse(IPAdd), ServerUDPPortSend);//255.255.255.255                ServerSocketSender.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.Broadcast, 1);
                ServerSocketSender.SendTo(data, iepBroadcast);
                ServerSocketSender.Close();
            }
            catch (Exception se)
            {
                BizLogic.LogWriter.AddSystemException(se);
            }        }        /// <summary>
        /// 后台监听接收
        /// </summary>
        public static void UDPOnListen()
        {
            try
            {
                 
                    dataBuffers = new byte[2048];
                    //svrIPAddress = GetLocalIP();
                    //System.Windows.Forms.MessageBox.Show(svrIPAddress.ToString(), svrUDPPortReceive.ToString());                    ServerEndPoint = new IPEndPoint(svrIPAddress, svrUDPPortReceive);                    UDPReceiveCallback = new AsyncCallback(UDPDataReceived);                    ServerSocketReceiver = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
                    ServerSocketReceiver.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.Broadcast, true);
                   
                    //ServerSocketReceiver.Bind(ServerEndPoint);//不允许运行第二个该下载工具,在这会报异常
                    try
                    {
                        ServerSocketReceiver.Bind(ServerEndPoint);//不允许运行第二个该下载工具,在这会报异常
                    }
                    catch (System.Net.Sockets.SocketException ex)
                    {
                        if (ex.SocketErrorCode == System.Net.Sockets.SocketError.AddressAlreadyInUse)
                        {
                            System.Windows.Forms.MessageBox.Show("监听端口已被其他程序占用，不能正确获得在线播放器信息，请退出程序？",
                          "端口占用错误", System.Windows.Forms.MessageBoxButtons.OK, System.Windows.Forms.MessageBoxIcon.Error);
                           
                        }
                        throw ex;                    }                    ServerSocketReceiver.ReceiveTimeout = 5;
                    ServerSocketReceiver.ReceiveBufferSize = 2048;                    ServerSocketReceiver.BeginReceiveFrom(dataBuffers, 0, dataBuffers.Length, SocketFlags.None,
                        ref   ServerEndPoint, UDPReceiveCallback, ServerSocketReceiver);
                             }
            catch (Exception ex)
            {
                BizLogic.LogWriter.AddSystemException(ex);
            }        }
        /// <summary>
        /// UDP回调
        /// </summary>
        /// <param name="ar"></param>
        private static void UDPDataReceived(IAsyncResult ar)
        {
            try
            {
                Socket udpSocket = ar.AsyncState as Socket;
                //070128  退出时异常：由于线程退出或应用程序请求，已放弃 I/O 操作
                int bytesRecved = udpSocket.EndReceiveFrom(ar, ref   (EndPoint)ServerEndPoint);
                //当收到数据后，数据已在dataBuffers，把dataBuffers转换成可识别的结构体，依据命令类型Type                //接收到的package是来自哪个ipaddress，把dataBuffers，ipaddress传过去，在第一次刷新时显示
                BizLogic.DataProcessor.DataFilter(dataBuffers);
                System.Threading.Thread.Sleep(5);
                ServerSocketReceiver.BeginReceiveFrom(dataBuffers, 0, dataBuffers.Length, SocketFlags.None,
                    ref  ServerEndPoint, UDPReceiveCallback, ServerSocketReceiver);
            }
            catch (Exception ex)
            {
                BizLogic.LogWriter.AddSystemException(ex);
            }
        }
        public static bool IsUDPConnected()
        {
            if (ServerSocketReceiver.Connected == true)//判断UDP接受的状态
            {
                return true;
            }
            else
            {
                return false;
            }
        }
        public static void Close()
        {
            if (ServerSocketReceiver == null)
                return;
            if (ServerSocketReceiver.Connected == true)
            { ServerSocketReceiver.Close(); }
        }
     }

Answer 2

确实应该是6000端口，因为你使用的是UDP协议，这个协议是不会保持连接的，是不可靠连接。
如果是改用TCP协议的话，就可以使用原来的连接，而不需要新建一个连接。

Answer 3

通用的，客户端和服务端的监听端口互换一下就可以了，用时直接UDPSocketService.去调启动            ////启动UDP套接字监听----20080408            UDPSocketService.ServerIPAddress = startip;
            UDPSocketService.ServerUDPPortReceive = startport;
            UDPSocketService.UDPOnListen(); 关闭 
 UDPSocketService.Close();点对点发送
UDPSocketService.UDPDataSendTo（你的数据，目的地）收包要另写一个静态方法
//  BizLogic.DataProcessor.DataFilter(dataBuffers);

Answer 4

不太喜欢全是static的类型，比较难做单元测试。