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C#中判断本地系统的网络连接状态的方法

  • 时间:2020-07-06 16:24 编辑: 来源: 阅读:
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摘要:C#中判断本地系统的网络连接状态的方法
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:
[b][i]lpdwFlags[/i][out][/b]
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。
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.
[b][i]dwReserved[/i][in][/b]
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[b]GetLastError[/b]来接收错误代码。
 
示例:
[u]复制代码[/u] 代码如下:
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: [img]http://files.jb51.net/file_images/article/201310/2013100916280811.jpg[/img]
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