C#判断本地系统的网络连接状态

转自：http://www.cnblogs.com/GaoHuhu/archive/2013/06/03/3114950.html

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_CONFIGURED0x40
Local system has a valid connection to the Internet, but it might or might not be currently connected.
INTERNET_CONNECTION_LAN 0x02
Local system uses a local area network to connect to the Internet.
INTERNET_CONNECTION_MODEM0x01
Local system uses a modem to connect to the Internet.
INTERNET_CONNECTION_MODEM_BUSY0x08
No longer used.
INTERNET_CONNECTION_OFFLINE 0x20
Local system is in offline mode.
INTERNET_CONNECTION_PROXY0x04
Local system uses a proxy server to connect to the Internet.
INTERNET_RAS_INSTALLED0x10
Local system has RAS installed.
dwReserved[in]
保留值。必须为0。
 
返回值：
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。
 
示例：
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using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Runtime.InteropServices;
 
namespace ConsoleApplication1
{
    class Program
    {
        private const int INTERNET_CONNECTION_MODEM = 1;
 
        private const int INTERNET_CONNECTION_LAN = 2;
 
        private const int INTERNET_CONNECTION_PROXY = 4;
 
        private const int INTERNET_CONNECTION_MODEM_BUSY = 8;
 
        [DllImport("winInet.dll ")]
 
        //声明外部的函数：
 
        private static extern bool InternetGetConnectedState(
            ref  int Flag,
            int dwReserved
        );
 
        static void Main(string[] args)
        {
            int Flag = 0;
 
            string netStates = "";
 
            if (!InternetGetConnectedState(ref Flag, 0))
            {
                Console.WriteLine("no！");
            }
            else
            {
 
                if ((Flag & INTERNET_CONNECTION_MODEM) != 0)
 
                    netStates += " Connect by MODEM /n";
 
                if ((Flag & INTERNET_CONNECTION_LAN) != 0)
 
                    netStates += "Connect by LAN  /n";
 
                if ((Flag & INTERNET_CONNECTION_PROXY) != 0)
 
                    netStates += "Connect by PROXY /n";
 
                if ((Flag & INTERNET_CONNECTION_MODEM_BUSY) != 0)
 
                    netStates += " MODEM is busy  /n";
 
            }
 
            Console.WriteLine(netStates);
            Console.ReadLine();
        }
    }
}

 

截图：

 

posted @ 2013-06-26 19:25  ADTL  阅读(480)  评论(0)    收藏  举报