根据当前IP获取当时所在信息

　　现在很多系统，都要在登录时候，确定当前用户所在的位置。这里记录一个C#使用Http的方式获取当前IP所在的位置信息。主要使用的api是新浪的接口。

 public partial class sina : System.Web.UI.Page
 {
     protected string ip = "171.216.18.89";
     protected void Page_Load(object sender, EventArgs e)
     {
         //if (IPOperation.GetIP() != "127.0.0.1")
         //{
         //    ip = IPOperation.GetIP();
         //}
         this.ClientScript.RegisterStartupScript(this.GetType(), "message", "<script language='javascript' defer>alert('" + GetCityByIP(ip).ToString() + "');</script>");

     }
     private string GetCityByIP(string ip)
     {
         string cityName = "成都";
         if (!string.IsNullOrEmpty(ip))
         {
             string url = "http://int.dpool.sina.com.cn/iplookup/iplookup.php?format=js&ip=" + ip;
             HttpWebRequest request = WebRequest.Create(url) as HttpWebRequest;
             request.Method = "POST";
             request.ContentType = "application/json;charset=utf-8";
             Stream stream = request.GetResponse().GetResponseStream();
             StreamReader sr = new StreamReader(stream, Encoding.UTF8);
             string str = sr.ReadToEnd().Split('=')[].ToString().TrimEnd(';');

             IPArea list = new JavaScriptSerializer().Deserialize<IPArea>(str);
             cityName = list.city;
         }
         return cityName;
     }
 }
 class IPArea
 {
     public int ret { get; set; }
     public string start { get; set; }
     public string end { get; set; }
     public string country { get; set; }
     public string province { get; set; }
     public string city { get; set; }
     public string district { get; set; }
     public string isp { get; set; }
     public string type { get; set; }
     public string desc { get; set; }
 }

　　主要先创建一个HttpWebRequest，定义请求方式及返回数据的结构和编码。这里使用JavaScriptSerializer将返回的json对象反序列化为对象。关于对象的信息就不记载了。