使用InternetGetConnectedState判断本地网络状态（C#举例）

函数原型：函数InternetGetConnectedState返回本地系统的网络连接状态。

语法：

BOOL InternetGetConnectedState(

__out LPDWORD lpdwFlags,

__in DWORD dwReserved

);

参数：

lpdwFlags[out]

指向一个变量，该变量接收连接描述内容。该参数在函数返回FLASE时仍可以返回一个有效的标记。该参数可以为下列值的一个或多个

值	含义
INTERNET_CONNECTION_CONFIGURED   0x40(64)	Local system has a valid connection to the Internet, but it might or might not be currently connected.
INTERNET_CONNECTION_LAN                   0x02(2)	Local system uses a local area network to connect to the Internet.
INTERNET_CONNECTION_MODEM0             x01(1)	Local system uses a modem to connect to the Internet.
INTERNET_CONNECTION_MODEM_BUSY0   x08(8)	No longer used.
INTERNET_CONNECTION_OFFLINE             0x20(16)	Local system is in offline mode.
INTERNET_CONNECTION_PROXY                0x04(4)	Local system uses a proxy server to connect to the Internet.
INTERNET_RAS_INSTALLED                        0x10(8)	Local system has RAS installed.

dwReserved[in]

保留值。必须为0。

当存在一个modem或一个LAN连接时，返回TRUE，当不存在internet连接或所有的连接当前未被激活时，返回false。

当该函数返回false时，程序可以调用 GetLastError来接收错误代码。

运行效果：

代码：

using System;

using System.Collections.Generic;

using System.Text;

using System.Net.NetworkInformation;



namespace ConsoleApplication1

{

    class Program

    {

        public static void Main(string[] args)

        {

            string url = "www.baidu.com;www.sina.com;www.cnblogs.com;www.google.com;www.163.com;www.csdn.com";

            string[] urls = url.Split(new char[] { ';' });

            CheckServeStatus(urls);



            Console.ReadKey();

        }

        

        /// <summary>

        /// 检测网络连接状态

        /// </summary>

        /// <param name="urls"></param>

        public static void CheckServeStatus(string[] urls)

        {

            int errCount = 0;//ping时连接失败个数



            if (!LocalConnectionStatus())

            {

                Console.WriteLine("网络异常~无连接");

            }

            else if (!MyPing(urls, out errCount))

            {

                if ((double)errCount / urls.Length >= 0.3)

                {

                    Console.WriteLine("网络异常~连接多次无响应");

                }

                else

                {

                    Console.WriteLine("网络不稳定");

                }

            }

            else

            {

                Console.WriteLine("网络正常");

            }

        }



        #region 网络检测



         private const int INTERNET_CONNECTION_MODEM = 1;

        private const int INTERNET_CONNECTION_LAN = 2;



        [System.Runtime.InteropServices.DllImport("winInet.dll")]

        private static extern bool InternetGetConnectedState(ref int dwFlag, int dwReserved);



        /// <summary>

        /// 判断本地的连接状态

         /// </summary>

        /// <returns></returns>

        private static bool LocalConnectionStatus()

        {

            System.Int32 dwFlag = new Int32();

            if (!InternetGetConnectedState(ref dwFlag, 0))

            {

                Console.WriteLine("LocalConnectionStatus--未连网!");

                return false;

            }

            else

            {

                if ((dwFlag & INTERNET_CONNECTION_MODEM) != 0)

                {

                    Console.WriteLine("LocalConnectionStatus--采用调制解调器上网。");

                    return true;

                }

                else if ((dwFlag & INTERNET_CONNECTION_LAN) != 0)

                {

                    Console.WriteLine("LocalConnectionStatus--采用网卡上网。");

                    return true;

                }

            }

            return false;

        }



        /// <summary>

        /// Ping命令检测网络是否畅通

        /// </summary>

        /// <param name="urls">URL数据</param>

        /// <param name="errorCount">ping时连接失败个数</param>

        /// <returns></returns>

        public static bool MyPing(string[] urls, out int errorCount)

        {

            bool isconn = true;

            Ping ping = new Ping();

            errorCount = 0;

            try

            {

                PingReply pr;

                for (int i = 0; i < urls.Length; i++)

                {

                    pr = ping.Send(urls[i]);

                    if (pr.Status != IPStatus.Success)

                    {

                        isconn = false;

                        errorCount++;

                    }

                    Console.WriteLine("Ping " + urls[i] + "    " + pr.Status.ToString());

                }

            }

            catch

            {

                isconn = false;

                errorCount = urls.Length;

            }

            //if (errorCount > 0 && errorCount < 3)

            //  isconn = true;

            return isconn;

        }



        #endregion

    }

}