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net判断网络是否有链接

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Runtime.InteropServices;

namespace Pinyin
{
    public partial class Form4 : Form
    {
        // 定义常量
        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.
        public Form4()
        {
            InitializeComponent();
        }
        //定义(引用)API函数
        [DllImport("wininet.dll")]
        public static extern bool InternetGetConnectedState(out   long lpdwFlags, long dwReserved);

        private void button1_Click(object sender, EventArgs e)
        {
            long lfag;
            string strConnectionDev = "";
            if (InternetGetConnectedState(out lfag, 0))
                strConnectionDev = "网络连接正常!";//程正伟的博客 http://www.webczw.com/
            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";
            MessageBox.Show(strConnectionDev);   
        }  
    }
}
 

作者:Wilber 类别:编程学习 时间:2010/10/15 1:40:47 评论:0 点击119
标签:  webczw,伟博小城
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