#region ---判断网络连接是否正常的方法---------
private const int INTERNET_CONNECTION_MODEM = 1;
private const int INTERNET_CONNECTION_LAN = 2;
[DllImport("winInet.dll")]
private static extern bool InternetGetConnectedState(ref int dwFlag, int dwReserved);//调用的方法(Winform为例,放一个按钮,单击即可):

private void button6_Click(object sender, EventArgs e)
{
System.Int32 dwFlag = new int();
if (!InternetGetConnectedState(ref dwFlag, 0))
MessageBox.Show("未连网!");
else if ((dwFlag & INTERNET_CONNECTION_MODEM) != 0)
MessageBox.Show("采用调治解调器上网。");
else if ((dwFlag & INTERNET_CONNECTION_LAN) != 0)
MessageBox.Show("采用网卡上网。");
}
#endregion