如何返回KML內容

Question

我正在嘗試烹飪連接到數據庫的網絡api，獲取一些地理數據，然后返回將由網頁使用​​的KML內容（在Google Maps iframe / div上顯示信息）。

我正在使用SharpKML（而且我不知道這是否是正確的選擇）：

public class KmlController : ApiController
{
    public HttpResponseMessage Get()
    {
        Point point = new Point();
        point.Coordinate = new Vector(37.42052549, -122.0816695);

        Placemark placemark = new Placemark();
        placemark.Name = "Somewhere";
        placemark.Geometry = point;

        Kml kml = new Kml();
        kml.Feature = placemark;

        return Request.CreateResponse(HttpStatusCode.OK, kml, new XmlMediaTypeFormatter(), "application/vnd.google-earth.kml+xml");
    }
}

但是，當我致電http：//something.on.my.lan/api/kml時，出現此異常：

System.InvalidOperationException：“ ObjectContent`1”類型未能序列化內容類型為“ application / vnd.google-earth.kml + xml”的響應正文； 字符集= UTF-8' 。

我想念什么？

解

不幸的是，正如此答案所述，即使我設法即時創建KML內容，它也不會顯示在地圖上，因為該URL必須由Google公開訪問（出於緩存目的）。 我必須改變方法。

Answer 1

首先嘗試一下，我想知道任何對象的序列化是否存在問題：

private string SerializeObject<T>(this T toSerialize)
{
    XmlSerializer xmlSerializer = new XmlSerializer(toSerialize.GetType());
    StringWriter textWriter = new StringWriter();

    xmlSerializer.Serialize(textWriter, toSerialize);
    return textWriter.ToString();
}


public class KmlController : ApiController
{
    public string Get()
    {
        Point point = new Point();
        point.Coordinate = new Vector(37.42052549, -122.0816695);

        Placemark placemark = new Placemark();
        placemark.Name = "Somewhere";
        placemark.Geometry = point;

        Kml kml = new Kml();
        kml.Feature = placemark;

        return SerializeObject<Kml>(kml);;
    }
}

如果失敗，建議您參考序列化文檔，以便找到哪個對象未正確序列化。

http://msdn.microsoft.com/en-us/library/system.serializableattribute.aspx

Answer 2

這對我有用...

    public static byte[] SerializeKml(this KmlFile kml)
    {
        var serializer = new Serializer(); 
        serializer.Serialize(kml.Root); 
        var str = serializer.Xml;

        var bytes = new byte[str.Length * sizeof(char)];
        Buffer.BlockCopy(str.ToCharArray(), 0, bytes, 0, bytes.Length);
        return bytes;
    }

    public ActionResult GetKml()
    {
        Placemark placemark = new Placemark
        {
            Geometry = new Point { Coordinate = new Vector(-13.163959, -72.545992) },
            Name = "Machu Picchu",
        };

        var kml = KmlFile.Create(placemark, false);
        var fcResult = new FileContentResult(kml.SerializeKml(), "application/vnd.google-earth.kml+xml") { FileDownloadName = "MachuPicchu.kml" };
        return fcResult;
    }