获取用户电脑的上网IP地址

在项目中经常要获取用户的上网的IP地址，如何获取用户的IP地址，方法很多，现在介绍以下2种。

/// <summary>
/// 获取本机在局域网的IP地址
/// </summary>
/// <returns></returns>
private string GetLocalIPAddress()
{
System.Net.IPAddress[] addressList = Dns.GetHostEntry(Dns.GetHostName()).AddressList;
string strNativeIP = "";
string strServerIP = "";
if (addressList.Length > 1)
{
strNativeIP = addressList[0].ToString();
strServerIP = addressList[1].ToString();
}
else if(addressList.Length==1)
{
strServerIP = addressList[0].ToString();
}
return strServerIP;
}

另外一种就是抓取网页中查询到的上网地址的IP来实现的。实现如下：

/// <summary>
/// 获取本机的上网IP
/// </summary>
/// <returns></returns>
private string GetConnectNetAddress()
{
string strUrl = "http://www.ip138.com/ip2city.asp"; //获得IP的网址
Uri uri = new Uri(strUrl);
WebRequest webreq = WebRequest.Create(uri);
Stream s = webreq.GetResponse().GetResponseStream();
StreamReader sr = new StreamReader(s, Encoding.Default);
string all = sr.ReadToEnd(); //读取网站返回的数据 格式：您的IP地址是：[x.x.x.x]
int i = all.IndexOf("[") + 1;
string tempip = all.Substring(i, 15);
string ip = tempip.Replace("]", "").Replace(" ", "").Replace("<", "");
return ip;
}