如何使用c#查找经纬度

你可以试试NuGet包GoogleMaps。LocationServices，或者只是旋转它的源代码。它使用Google的REST API来获取给定地址的晚/长，反之亦然，而不需要API密钥。

你可以这样使用:

public static void Main()
{
    var address = "Stavanger, Norway";
    var locationService = new GoogleLocationService();
    var point = locationService.GetLatLongFromAddress(address);
    var latitude = point.Latitude;
    var longitude = point.Longitude;
    // Save lat/long values to DB...
}

如果你想使用谷歌地图API，看看他们的REST API，你不需要安装谷歌地图API，只需发送一个请求，如

http://maps.googleapis.com/maps/api/geocode/xml?address=1600+Amphitheatre+Parkway,+Mountain+View,+CA&sensor=true_or_false

，您将得到一个响应XML。

对于响应JSON:

https://maps.googleapis.com/maps/api/geocode/json?address=1600+Estância+Sergipe,&key=**YOUR_API_KEY**

更多信息请看

https://developers.google.com/maps/documentation/geocoding/index GeocodingRequests

     /*Ready to use code :  simple copy paste GetLatLong*/
    public class AddressComponent
    {
        public string long_name { get; set; }
        public string short_name { get; set; }
        public List<string> types { get; set; }
    }
    public class Northeast
    {
        public double lat { get; set; }
        public double lng { get; set; }
    }
    public class Southwest
    {
        public double lat { get; set; }
        public double lng { get; set; }
    }
    public class Bounds
    {
        public Northeast northeast { get; set; }
        public Southwest southwest { get; set; }
    }
    public class Location
    {
        public double lat { get; set; }
        public double lng { get; set; }
    }
    public class Northeast2
    {
        public double lat { get; set; }
        public double lng { get; set; }
    }
    public class Southwest2
    {
        public double lat { get; set; }
        public double lng { get; set; }
    }
    public class Viewport
    {
        public Northeast2 northeast { get; set; }
        public Southwest2 southwest { get; set; }
    }
    public class Geometry
    {
        public Bounds bounds { get; set; }
        public Location location { get; set; }
        public string location_type { get; set; }
        public Viewport viewport { get; set; }
    }
    public class Result
    {
        public List<AddressComponent> address_components { get; set; }
        public string formatted_address { get; set; }
        public Geometry geometry { get; set; }
        public string place_id { get; set; }
        public List<string> types { get; set; }
    }
    public class RootObject
    {
        public List<Result> results { get; set; }
        public string status { get; set; }
    }

    public static RootObject GetLatLongByAddress(string address)
    {
        var root = new RootObject();
        var url =
            string.Format(
                "http://maps.googleapis.com/maps/api/geocode/json?address={0}&sensor=true_or_false", address);
        var req = (HttpWebRequest)WebRequest.Create(url);
        var res = (HttpWebResponse)req.GetResponse();
        using (var streamreader=new StreamReader(res.GetResponseStream()))
        {
            var result = streamreader.ReadToEnd();
            if (!string.IsNullOrWhiteSpace(result))
            {
                root = JsonConvert.DeserializeObject<RootObject>(result);
            }
        }
        return root;

    }

          /* Call This*/
var destination_latLong = GetLatLongByAddress(um.RouteDestination);
var lattitude =Convert.ToString( destination_latLong.results[0].geometry.location.lat, CultureInfo.InvariantCulture);
 var longitude=Convert.ToString( destination_latLong.results[0].geometry.location.lng, CultureInfo.InvariantCulture);

您可以传递特定url的地址。你在返回值dt(datatable)

string url = "http://maps.google.com/maps/api/geocode/xml?address=" + address+ "&sensor=false";
WebRequest request = WebRequest.Create(url);
using (WebResponse response = (HttpWebResponse)request.GetResponse())
{
    DataTable dtCoordinates = new DataTable();
    using (StreamReader reader = new StreamReader(response.GetResponseStream(), Encoding.UTF8))
    {
        DataSet dsResult = new DataSet();
        dsResult.ReadXml(reader);
        dtCoordinates.Columns.AddRange(new DataColumn[4] { new DataColumn("Id", typeof(int)),
                    new DataColumn("Address", typeof(string)),
                    new DataColumn("Latitude",typeof(string)),
                    new DataColumn("Longitude",typeof(string)) });
        foreach (DataRow row in dsResult.Tables["result"].Rows)
        {
            string geometry_id = dsResult.Tables["geometry"].Select("result_id = " + row["result_id"].ToString())[0]["geometry_id"].ToString();
            DataRow location = dsResult.Tables["location"].Select("geometry_id = " + geometry_id)[0];
            dtCoordinates.Rows.Add(row["result_id"], row["formatted_address"], location["lat"], location["lng"]);
        }
    }
    return dtCoordinates;
}

除了Google之外，还有OpenStreetMap的nomatim api。

不像Google，他们没有每日限制，只要你不过度密集地使用它们(每秒超过一个请求)。下面的代码适用于Blazor服务器。

    [Inject] IJSRuntime _js { get; set; }
    public async Task<Coordinates> GetCoordinates(string city) {
        Coordinates coordinates = new Coordinates();
        string query= String.Format("https://nominatim.openstreetmap.org/search.php?q={0}&format=jsonv2", city);
        string result = GetRequest(query); //returns a stringified array of js objects
        IJSObjectReference objArray= await _js.InvokeAsync<IJSObjectReference>("JSON.parse", result); //parse the string to a js array
        IJSObjectReference obj = await objArray.InvokeAsync<IJSObjectReference>("shift"); //take the first element in the array
        string jsonResult = await _js.InvokeAsync<string>("JSON.stringify", obj);
        dynamic dynamicResult = JObject.Parse(jsonResult);
        coordinates.Latitude= dynamicResult.lat;
        coordinates.Longitude= dynamicResult.lon;
        return coordinates;
    }
    public string GetRequest(string url) {
        HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);
        request.AutomaticDecompression = DecompressionMethods.GZip | DecompressionMethods.Deflate;
        request.UserAgent = @"Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/51.0.2704.106 Safari/537.36";
        using (HttpWebResponse response = (HttpWebResponse)request.GetResponse())
        using (Stream stream = response.GetResponseStream())
        using (StreamReader reader = new StreamReader(stream))
        {
            return reader.ReadToEnd();
        }
    }
    public class Coordinates {
        public double Longitude { get; set; }
        public double Latitude { get; set; }
    }