public partial class Form1 : Form

    {

        public static Form1 mainFrm;

        public Form1()

        {

            mainFrm = this;

            InitializeComponent();

        }

  public static void WaitCallBackReceiveConnectedInfo(string connecetedIp,string leaveIp)

        {

           Form1.mainFrm.rtxtMsg.BeginInvoke(new InvokeDelegate(InvokeMethod), new object[] { connecetedIp, leaveIp });

        }

        public delegate void InvokeDelegate(string connecetedIp, string leaveIp);

        public static void InvokeMethod(string connecetedIp, string leaveIp)

        {

            if (connecetedIp != "")

            {

                Form1.mainFrm.cmbConnectedIP.Items.Add(connecetedIp);

                Form1.mainFrm.rtxtMsg.AppendText(connecetedIp+" 连接上来\r\n");

                Form1.mainFrm.cmbConnectedIP.SelectedIndex = ;

            }

            if (leaveIp != "")

            {

                Form1.mainFrm.cmbConnectedIP.Items.Remove(leaveIp);

                Form1.mainFrm.rtxtMsg.AppendText(leaveIp + " 离开\r\n");

            }

        }