C#判断是否连接外网

[DllImport(“winInet.dll”)]
        private static extern bool InternetGetConnectedState(ref int dwFlag, int dwReserved);
        private const int INTERNET_CONNECTION_MODEM = 1;
        private const int INTERNET_CONNECTION_LAN = 2;
        /// <summary>
        /// 判断本机是否联网
        /// </summary>
        /// <returns></returns>
        public static bool IsConnectNetwork()
        {
            try
            {
                int dwFlag = 0;

                //false表示没有连接到任何网络,true表示已连接到网络上
                if (!InternetGetConnectedState(ref dwFlag, 0))
                {

                    //if (!InternetGetConnectedState(ref dwFlag, 0))
                    //     Console.WriteLine(“未连网!”);
                    //else if ((dwFlag & INTERNET_CONNECTION_MODEM) != 0)
                    //    Console.WriteLine(“采用调治解调器上网。”);
                    //else if ((dwFlag & INTERNET_CONNECTION_LAN) != 0)
                    //    Console.WriteLine(“采用网卡上网。”); 
                    return false;
                }

                //判断当前网络是否可用
                IPAddress[] addresslist = Dns.GetHostAddresses(www.baidu.com);
                if (addresslist[0].ToString().Length <= 6)
                {
                    return false;
                }
            }
            catch (Exception ex)
            {
                return false;
            }
            return true;
        }