using System;

using System.Collections.Generic;

using System.ComponentModel;

using System.Data;

using System.Drawing;

using System.Text;

using System.Windows.Forms;

using System.Net.NetworkInformation;

using System.Runtime.InteropServices;

namespace NetWork

{

    public partial class Form1 : Form

    {

        public Form1()

        {

            InitializeComponent();

            NetworkChange.NetworkAvailabilityChanged += new NetworkAvailabilityChangedEventHandler(NetworkChange_NetworkAvailabilityChanged);

            NetworkChange.NetworkAddressChanged+=new NetworkAddressChangedEventHandler(NetworkChange_NetworkAddressChanged);

        }

        public void NetworkChange_NetworkAddressChanged(object sender, EventArgs e)

        {

            NetworkInterface[] adapters = NetworkInterface.GetAllNetworkInterfaces();

            foreach (NetworkInterface n in adapters)

            {

                if(n.NetworkInterfaceType!= NetworkInterfaceType.Loopback)

                    Console.WriteLine("Changed   {0} is {1}", n.Name, n.OperationalStatus);

            }

            Console.WriteLine("NetState  :  " + NetState());

        }

        public void NetworkChange_NetworkAvailabilityChanged(object sender, NetworkAvailabilityEventArgs e)

        {            

            Console.WriteLine("IsAvailable  :  "+e.IsAvailable);

            Console.WriteLine("NetState  :  " + NetState());

            

        }

        [DllImport("wininet.dll")]

        public static extern bool InternetGetConnectedState(out long lpdwFlags, long dwReserved);

        public static bool NetState()

        {

            //string url = http://www.baidu.com/;

            //if (url.StartsWith("http://")) url = url.Remove(0, "http://".length/);

            //try

            //{

            //    System.Net.IPHostEntry ipHost = System.Net.Dns.GetHostEntry(url);// System.Net.Dns.Resolve(url);

            //    return true;

            //}

            //catch //(System.Net.Sockets.SocketException se)

            //{

            //    //System.Diagnostics.Trace.Write(se.Message);

            //    return false;

            //}

            try

            {

                long lfag;

                if (InternetGetConnectedState(out lfag, 0))

                {                   

                    return true;   

                }

                return false;

            }

            catch

            {

                return false;

            }

        }

      }

}

 

 

 

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