其实就是使用了百度的IP库的功能接口，然后处理下就行了，效果图如下：
准备工作：
1.注册成为开度开发者，创建应用获得百度API调用的AK秘钥，百度开发中心地址：http://developer.baidu.com/
2.API 地址： http://developer.baidu.com/map/index.php?title=webapi/ip-api#.E4.BD.BF.E7.94.A8.E6.96.B9.E6.B3.95
3.准备开发咯，步骤如下：
(1)获取客户端IP
/// <summary>获取客户端IP地址（无视代理）</summary>
/// <returns>若失败则返回回送地址</returns>
public static string GetHostAddress()
{
string userHostAddress = HttpContext.Current.Request.UserHostAddress;
if (string.IsNullOrEmpty(userHostAddress))
{
userHostAddress = HttpContext.Current.Request.ServerVariables["REMOTE_ADDR"];
}
//最后判断获取是否成功，并检查IP地址的格式（检查其格式非常重要）
if (!string.IsNullOrEmpty(userHostAddress) && IsIP(userHostAddress))
{
return userHostAddress;
}
return "127.0.0.1";
}
/// <summary>
/// 检查IP地址格式
/// </summary>
/// <param name="ip"></param>
/// <returns></returns>
public static bool IsIP(string ip)
{
return System.Text.RegularExpressions.Regex.IsMatch(ip, @"^((2[0-4]\d|25[0-5]|[01]?\d\d?)\.){3}(2[0-4]\d|25[0-5]|[01]?\d\d?)$");
(2)获取编码服务地址
private const string THE_KEY = "***************"; //你的AK密钥
/// <summary>返回UTF-8编码服务地址</summary>
/// <returns>服务地址</returns>
public string GetPostUrl(string theIP)
{
string postUrl = "http://api.map.baidu.com/location/ip?ak=" + THE_KEY + "&ip=" + theIP + "&coor=bd09ll";
return postUrl;
}
(3)通过服务地址，得到地址解析结果
/// <summary> 返回结果（地址解析的结果） </summary>
public static string GetInfoByUrl(string url)
{
//调用时只需要把拼成的URL传给该函数即可。判断返回值即可
string strRet = null;
if (url == null || url.Trim().ToString() == "")
{
return strRet;
}
string targeturl = url.Trim().ToString();
try
{
HttpWebRequest hr = (HttpWebRequest)WebRequest.Create(targeturl);
hr.UserAgent = "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1)";
hr.Method = "GET";
hr.Timeout = 30 * 60 * 1000;
WebResponse hs = hr.GetResponse();
Stream sr = hs.GetResponseStream();
StreamReader ser = new StreamReader(sr, Encoding.Default);
strRet = ser.ReadToEnd();
}
catch (Exception ex)
{
strRet = null;
}
return strRet;
}
(4)最后简单的调用上面的方法，然后转换下字符串中转义字符
string theIP = YMethod.GetHostAddress();
string msg = YMethod.GetInfoByUrl(GetPostUrl(theIP));
msg = System.Text.RegularExpressions.Regex.Unescape(msg);
Response.Write(msg);
原文：http://www.cnblogs.com/zix1314/p/5084114.html