微软提供的函数不能再多网卡的情况下，判断指定网卡的网线连接状态。以下代码刚好能够解决这个问题。

 
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Net.NetworkInformation;
using System.Threading;
  
namespace NetworkAdapterTestEvent
{
    class Program
    {
        static void Main(string[] args)
        {
            NetworkAdapterAvailable newtest = new NetworkAdapterAvailable();
  
            newtest.Subscribe("本地连接",new NetworkAdapterAvailable.NetworkAdapterChangedEventHandler(NetowrkAdapter_changed));
            newtest.StartMonitor();
  
            Console.ReadLine();
            newtest.StopMonitor();
            newtest.Unsubscribe("本地连接", new NetworkAdapterAvailable.NetworkAdapterChangedEventHandler(NetowrkAdapter_changed));
        }
  
        static void NetowrkAdapter_changed(object sender, NetworkAdapterChangedArgument e)
        {
            Console.WriteLine("Name:{0}\\tStatus:{1}", e.AdapterName, e.AdapterStatus.ToString());
        }
    }
  
    public class NetworkAdapterAvailable
    {
        public delegate void NetworkAdapterChangedEventHandler(object send , NetworkAdapterChangedArgument e);
          
        public event NetworkAdapterChangedEventHandler NetworkAdapterChanged;
  
        private Thread _AdapterCheckThread;
        private string _AdapterName;
        private bool _Stop = false;
        private NetworkInterface[] _adapters;
  
        public NetworkAdapterAvailable()
        {
            _adapters = NetworkInterface.GetAllNetworkInterfaces();
        }
  
        /// <summary>
        /// 订阅
        /// </summary>
        /// <param name="_adaptername_"></param>
        /// <param name="_EventHandler_"></param>
        public void Subscribe(string _adaptername_ , NetworkAdapterChangedEventHandler _EventHandler_)
        {
            _AdapterName = _adaptername_;
  
            if (_EventHandler_ != null)
            {
                NetworkAdapterChanged += _EventHandler_;
            }
        }
  
        /// <summary>
        /// 取消订阅
        /// </summary>
        /// <param name="_adaptername_"></param>
        /// <param name="_EventHandler_"></param>
        public void Unsubscribe(string _adaptername_, NetworkAdapterChangedEventHandler _EventHandler_)
        {
            if (_EventHandler_ != null)
            {
                NetworkAdapterChanged -= _EventHandler_;
            }
        }
  
        /// <summary>
        /// 开始监控
        /// </summary>
        public void StartMonitor()
        {
            _AdapterCheckThread = new Thread(new ThreadStart(AdapterCheckHandler));
            _AdapterCheckThread.IsBackground = true;
            _AdapterCheckThread.Start();
        }
  
        public void StopMonitor()
        {
            _Stop = true;
  
            if (_AdapterCheckThread != null)
            {
                _AdapterCheckThread.Join();
            }
  
        }
  
        private void AdapterCheckHandler()
        {
            while (!_Stop)
            {
                NetworkInterface[] __adapters = NetworkInterface.GetAllNetworkInterfaces();
  
                for (int i = 0; i < __adapters.Length; i++)
                {
                    if (_adapters[i].Name == _AdapterName)
                    {
                        if (_adapters[i].OperationalStatus != __adapters[i].OperationalStatus)
                        {
                            NetworkAdapterChanged(this, new NetworkAdapterChangedArgument(_AdapterName, __adapters[i].OperationalStatus));
                            _adapters[i] = __adapters[i];
                        }
                    }
                }
  
                Thread.Sleep(100);
            }
        }
    }
  
    public class NetworkAdapterChangedArgument : EventArgs
    {
        private string _AdapterName;
        private OperationalStatus _AdapterStatus;
  
        public NetworkAdapterChangedArgument(string _adaptername_, OperationalStatus _adapterstatus_)
        {
            _AdapterName = _adaptername_;
            _AdapterStatus = _adapterstatus_;
        }
  
        public string AdapterName
        {
            get { return _AdapterName; }
        }
  
        public OperationalStatus AdapterStatus
        {
            get { return _AdapterStatus; }
        }
    }
}