判断网络类型的代码(收藏)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Xml.Linq;
using System.Runtime.InteropServices;

namespace ConsoleApplication1
{
    class Program
    {
        private const long INTERNET_CONNECTION_MODEM = 1;//Local system uses a modem to connect to the Internet.
        private const long INTERNET_CONNECTION_LAN = 2; //Local system uses a local area network to connect to the Internet.
        private const long INTERNET_CONNECTION_PROXY = 4;//Local system uses a proxy server to connect to the Internet.
        private const long INTERNET_CONNECTION_MODEM_BUSY = 8;   //No longer used.
        private const long INTERNET_CONNECTION_CONFIGURED = 64; //Local system has a valid connection to the Internet, but it might or might not be currently connected.
        private const long INTERNET_CONNECTION_OFFLINE = 32; // Local system is in offline mode.
        private const long INTERNET_RAS_INSTALLED = 16; //Local system has RAS installed.

        [DllImport("wininet.dll")]
        public static extern bool InternetGetConnectedState(out   long lpdwFlags, long dwReserved);

        static void Main(string[] args)
        {
            long lfag;
            string strConnectionDev = "";
            if (InternetGetConnectedState(out lfag, 0))
                strConnectionDev = "网络连接正常!";
            else
                strConnectionDev = "网络连接不可用!";
            if ((lfag & INTERNET_CONNECTION_OFFLINE) > 0)
                strConnectionDev += "OFFLINE 本地系统处于离线模式。";
            if ((lfag & INTERNET_CONNECTION_MODEM) > 0)
                strConnectionDev += "Modem 本地系统使用调制解调器连接到互联网。";
            if ((lfag & INTERNET_CONNECTION_LAN) > 0)
                strConnectionDev += "LAN 本地系统使用的局域网连接到互联网。";
            if ((lfag & INTERNET_CONNECTION_PROXY) > 0)
                strConnectionDev += "a   Proxy";
            if ((lfag & INTERNET_CONNECTION_MODEM_BUSY) > 0)
                strConnectionDev += "Modem   but   modem   is   busy";
            //this.Response.Write("<script>alert('" + strConnectionDev + "');</script>");
            Console.WriteLine(strConnectionDev);
            Console.Read();
        }
    }
}