如何判断网络连接状态和获取网络IP地址
问题1：如何判断网络已经连接(50)
问题2：获取网络IP地址(50)
要求能适应拨号上网和通过局域网上网。两种上网方式

[解决办法]
IPHostEntry获取IP
你尝试连一个公共的网站，连通就可以说明网络是已经连接的了。
[解决办法]
//获取IP地址
public string GetIPAddress()
{
IPAddress ip = new IPAddress(Dns.GetHostByName(Dns.GetHostName()).AddressList[0].Address);
return ip.ToString();
}
[解决办法]
判断网络已经连接

C# code

[DllImport("wininet.dll")]        private extern static bool InternetGetConnectedState(out int connectionDescription, int reservedValue);        public bool IsInternetConnected()        {            int i = 0;            return InternetGetConnectedState(out i, 0);        }
[解决办法]
AutoResetEvent waiter = new AutoResetEvent(false);
           Ping myPing = new Ping();
           myPing.PingCompleted += new PingCompletedEventHandler(myPing_PingCompleted);
           string data = "OK";  
           byte[] buffer = Encoding.ASCII.GetBytes(data);
           int timeout = 10000;
           PingOptions options = new PingOptions(64, true);
           myPing.SendAsync(_AppState.ServerName, timeout, buffer, options, waiter);  
或
IPGlobalProperties properties = IPGlobalProperties.GetIPGlobalProperties();
           TcpConnectionInformation[] connections = properties.GetActiveTcpConnections();
           foreach (TcpConnectionInformation info in connections) {
               if (info.RemoteEndPoint.Equals(targetEndPoint)) {
                   _AppState.OnlineStatus = Constant.ONLINE_STATUS_ONLINE;
                   isOnline = true;
                   break;
               }
           }
或
   [DllImport("wininet.dll")]
   private extern static bool InternetGetConnectedState(out int connectionDescription, int reservedValue);


  System.Net.IPAddress[] addressList = Dns.GetHostByName(Dns.GetHostName()).AddressList; 
           for (int i = 0; i < addressList.Length; i ++)  
           {  
               s += addressList[i].ToString();  
           }  

[解决办法]
 string st = "";
               ManagementClass mc = new ManagementClass("Win32_NetworkAdapterConfiguration");
               ManagementObjectCollection moc = mc.GetInstances();
               foreach (ManagementObject mo in moc)
               {
                   if ((bool)mo["IPEnabled"] == true)
                   {
                       System.Array ar;
                       ar = (System.Array)(mo.Properties["IpAddress"].Value);
                       st = ar.GetValue(0).ToString();
                       break;
                   }
               }
               moc = null;
               mc = null;

[解决办法]
照顾楼主不认识VB.NET的语法,转换为C#  
C# code
using System;using System.Collections.Generic;using System.ComponentModel;using System.Data;using System.Drawing;using System.Linq;using System.Text;using System.Text.RegularExpressions;using System.Windows.Forms;using System.Net;namespace WindowsFormsApplication1{    public partial class Form1 : Form    {        public Form1()        {            InitializeComponent();        }        private void button1_Click(object sender, EventArgs e)        {            WebClient wb = new WebClient();            String strIP = "";            String strContent = "";            Regex regIP = new Regex("\\d{1,3}.\\d{1,3}.\\d{1,3}.\\d{1,3}");            try            {                strContent = wb.DownloadString("http://www.ip138.com/ips8.asp");                if (strContent.IndexOf("IP地址查询") >= 1)                {                    textBox1.Text = "爽,可以上网!";                    strIP = regIP.Match(strContent).ToString();                    if (strIP.Trim() != "")                    {                        textBox2.Text = "俺的IP是:" + strIP;                    }                    else                    {                        textBox2.Text = "虽然俺上网了,但是俺是黑户,没IP!";                    }                }            }            catch            {                textBox1.Text = "真不爽,不能上网,我去炸了电信!";                textBox2.Text = "不能上网,没IP!";            }        }    }} 
 
[解决办法]
C# code
private static string getIPAddress ( ) {    System.Net.IPAddress addr;    // 获得本机局域网IP地址    addr = new System.Net.IPAddress ( Dns.GetHostByName ( Dns.GetHostName ( ) ) .AddressList [0].Address ) ;    return addr.ToString ( ) ; } }
[解决办法]
DNS.GetHost("www.sohu.com")可以Get出来就证明上网了