Get IP geolocation using C# & WPF

问题

I am doing a module which can display my city, state, latitude and longitude, using IP address of the device I am using. However, I can't get it right. Below, there is my code which I referred to another website:

internal GeoLoc GetMyGeoLocation()
{
    try
    {
        //create a request to geoiptool.com
        var request = WebRequest.Create(new Uri("http://geoiptool.com/data.php")) as HttpWebRequest;


    if (request != null)
    {
        //set the request user agent
        request.UserAgent = "Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.0; SLCC1; .NET CLR 2.0.50727)";

        //get the response
        using (var webResponse = (request.GetResponse() as HttpWebResponse))
            if (webResponse != null)
                using (var reader = new StreamReader(webResponse.GetResponseStream()))
                {

                    //get the XML document
                    var doc = new XmlDocument();
                    doc.Load(reader);

                    //now we parse the XML document
                    var nodes = doc.GetElementsByTagName("marker");

                    Guard.AssertCondition(nodes.Count > 0,"nodes",new object());
                    //make sure we have nodes before looping
                    //if (nodes.Count > 0)
                    //{
                        //grab the first response
                        var marker = nodes[0] as XmlElement;

                        Guard.AssertNotNull(marker, "marker");

                        //get the data and return it
                        _geoLoc.City = marker.GetAttribute("city");
                        _geoLoc.Country = marker.GetAttribute("country");
                        _geoLoc.Code = marker.GetAttribute("code");
                        _geoLoc.Host = marker.GetAttribute("host");
                        _geoLoc.Ip = marker.GetAttribute("ip");
                        _geoLoc.Latitude = marker.GetAttribute("lat");
                        _geoLoc.Lognitude = marker.GetAttribute("lng");
                        _geoLoc.State = GetMyState(_geoLoc.Latitude, _geoLoc.Lognitude);

                        return _geoLoc;
                    //}
                }
    }

    // this code would only be reached if something went wrong 
    // no "marker" node perhaps?
    return new GeoLoc();
}
catch (Exception ex)
{
    throw;
}

}

All the code has no problem. The only problem would be the _geoLoc, it keep prompt out red lines below each of them. What does it mean? Thank you.

回答1:

As others have pointed out, _geoLoc isn't defined. Try something like this

internal GeoLoc GetMyGeoLocation()
{
    try
    {
        //create a request to geoiptool.com
        var request = WebRequest.Create(new Uri("http://geoiptool.com/data.php")) as HttpWebRequest;


    if (request != null)
    {
        //set the request user agent
        request.UserAgent = "Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.0; SLCC1; .NET CLR 2.0.50727)";

        //get the response
        using (var webResponse = (request.GetResponse() as HttpWebResponse))
            if (webResponse != null)
                using (var reader = new StreamReader(webResponse.GetResponseStream()))
                {

                    //get the XML document
                    var doc = new XmlDocument();
                    doc.Load(reader);

                    //now we parse the XML document
                    var nodes = doc.GetElementsByTagName("marker");

                    Guard.AssertCondition(nodes.Count > 0,"nodes",new object());
                    //make sure we have nodes before looping
                    //if (nodes.Count > 0)
                    //{
                        //grab the first response
                        var marker = nodes[0] as XmlElement;

                        Guard.AssertNotNull(marker, "marker");

                        var _geoLoc = new GeoLoc();
                        //get the data and return it
                        _geoLoc.City = marker.GetAttribute("city");
                        _geoLoc.Country = marker.GetAttribute("country");
                        _geoLoc.Code = marker.GetAttribute("code");
                        _geoLoc.Host = marker.GetAttribute("host");
                        _geoLoc.Ip = marker.GetAttribute("ip");
                        _geoLoc.Latitude = marker.GetAttribute("lat");
                        _geoLoc.Lognitude = marker.GetAttribute("lng");
                        _geoLoc.State = GetMyState(_geoLoc.Latitude, _geoLoc.Lognitude);

                        return _geoLoc;
                    //}
                }
           }

        // this code would only be reached if something went wrong 
        // no "marker" node perhaps?
        return new GeoLoc();
    }
    catch (Exception ex)
    {
        throw;
    }
}

回答2:

Seems like you dont have instenciated _geoLoc this should be instenciatted before you use it. try something like.

namespace MyNamespace
{
    public class GeoLoc
    {
        public string City { get; set; }

        public string Country { get; set; }

        public string Code { get; set; }

        public string Host { get; set; }

        public string Ip { get; set; }

        public string Latitude { get; set; }

        public string Lognitude { get; set; }

        public object State { get; set; }
    }
    public class TestGEO
    {
        internal GeoLoc GetMyGeoLocation()
        {
            GeoLoc _geoLoc = new GeoLoc();
            try
            {
                //create a request to geoiptool.com
                var request = WebRequest.Create(new Uri("http://geoiptool.com/data.php")) as HttpWebRequest;


                if (request != null)
                {
                    //set the request user agent
                    request.UserAgent = "Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.0; SLCC1; .NET CLR 2.0.50727)";

                    //get the response
                    using (var webResponse = (request.GetResponse() as HttpWebResponse))
                        if (webResponse != null)
                            using (var reader = new StreamReader(webResponse.GetResponseStream()))
                            {

                                //get the XML document
                                var doc = new XmlDocument();
                                doc.Load(reader);

                                //now we parse the XML document
                                var nodes = doc.GetElementsByTagName("marker");

                                // Guard.AssertCondition(nodes.Count > 0, "nodes", new object());
                                //make sure we have nodes before looping
                                //if (nodes.Count > 0)
                                //{
                                //grab the first response
                                var marker = nodes[0] as XmlElement;

                                //  Guard.AssertNotNull(marker, "marker");

                                //get the data and return it
                                _geoLoc.City = marker.GetAttribute("city");
                                _geoLoc.Country = marker.GetAttribute("country");
                                _geoLoc.Code = marker.GetAttribute("code");
                                _geoLoc.Host = marker.GetAttribute("host");
                                _geoLoc.Ip = marker.GetAttribute("ip");
                                _geoLoc.Latitude = marker.GetAttribute("lat");
                                _geoLoc.Lognitude = marker.GetAttribute("lng");
                                _geoLoc.State = GetMyState(_geoLoc.Latitude, _geoLoc.Lognitude);

                                return _geoLoc;
                                //}
                            }
                }

                // this code would only be reached if something went wrong 
                // no "marker" node perhaps?
                return _geoLoc;
            }
            catch (Exception ex)
            {
                throw;
            }
        }

        private object GetMyState(string p, string p_2)
        {
            ///do somting 
            return "State Name";
            //return you data;
        }
    }
}

来源：https://stackoverflow.com/questions/20117294/get-ip-geolocation-using-c-sharp-wpf