Question

I have made a program that takes the longitude and latitude from several properties on a london property portal.

What I am to do next is send those long+lat to geocode and return the full formatted address. The below code works for a majority of URLs that I have in my geocodeURL list, but occasionally it returns a null reference exception.

When I check the URL that failed and returned the exception manually in a browser, it works fine.

If that is the case, what am I doing wrong?

for (int i = 0; i < longitude.Count; i++)
        {
            Console.WriteLine(longitude[i]);
            Console.WriteLine(latitude[i]);
            //Console.WriteLine("http://maps.google.com/maps/api/geocode/xml?latlng=" + latitude[i] + "," + longitude[i] + "&sensor=false");
            geocodeURL.Add("https://maps.googleapis.com/maps/api/geocode/xml?latlng=" + latitude[i] + "," + longitude[i] + "&key=0000");
        }

        foreach (string i in geocodeURL)
        {

            try
            {
                var requestUri = string.Format(i);

                var request = WebRequest.Create(requestUri);
                var response = request.GetResponse();
                var xdoc = XDocument.Load(response.GetResponseStream());

                var result = xdoc.Element("GeocodeResponse").Element("result");
                var fullAddy = result.Element("formatted_address").Value;
                address.Add(fullAddy);
                Console.WriteLine(fullAddy);
            }
            catch (Exception e)
            {
                Console.WriteLine(i);
                Console.WriteLine(e);
            }       
        }

The XMl response looks like this:

<GeocodeResponse>
<status>OK</status>
 <result>
  <type>street_address</type>
  <formatted_address>4 Sydenham Ave, London SE26 6UH, UK</formatted_address>

One such example of the exception, and you can see the URL seems to be fine, but it throws an exception regardless... (I have blacked out the key fyi)

Answer 1

Google限制了您可以在一定时间内发送的结果数量。由于您一次发送数百个请求，因此您可能正在遇到此限制，并且错误是谷歌告诉您要么咳嗽现金或gtfo的错误。

如果您不想付款，可以每隔几个请求设置一个Thread.Sleep(2000)（或其他一些等待期）以达到限制。

Google Geocode null reference exception

1 个答案: