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Question

是否可以从OpenLayers编写和保存KML？有人知道出口一个的例子吗？

Answer 1

您只能将矢量要素导出为KML。

function GetKMLFromFeatures(features) {
    var format = new OpenLayers.Format.KML({
        'maxDepth':10,
        'extractStyles':true,
        'internalProjection': map.baseLayer.projection,
        'externalProjection': new OpenLayers.Projection("EPSG:4326")
    });

    return format.write(features);
}

更新

为了强制浏览器将KML字符串作为KML文件下载，您需要将该字符串发送回服务器端，以便将其作为要下载的文件返回到浏览器。

您尚未指定您在服务器端使用的语言/平台/等等。但这是我在C＃中所做的。

我创建了一个处理程序，它从查询字符串中获取文件名，从textarea表单中获取KML。

<强> KMLDownload.ashx：

<%@ WebHandler Language="C#" Class="KMLDownload" %>

using System;
using System.Web;

public class KMLDownload : IHttpHandler
{

    public void ProcessRequest(HttpContext context)
    {


        HttpResponse response = context.Response;

        string kml = context.Request["kml"];
        string filename = context.Request.QueryString["filename"];

        if (String.IsNullOrEmpty(kml))
        {
            context.Response.ContentType = "text/plain";
            context.Response.Write("{\"error\":\"No files recevied\"}");
        }
        else
        {

            if (String.IsNullOrEmpty(filename)){
                filename = "Features_KML.kml";
            }

            // force a download of the kml file.
            response.Clear();
            response.ContentType = "application/kml";
            response.AddHeader("Content-Disposition", "attachment; filename=" + filename);
            response.AddHeader("content-legth", kml.Length.ToString());
            response.Write(kml.ToString());
            response.End();
        }

    }

    public bool IsReusable
    {
        get
        {
            return false;
        }
    }

}

然后从我的JavaScript方面，我只是打电话给它开始下载：

var filename = "NameofKMLfileI_WANT.kml";

var url = "secure/KMLDownload.ashx";
if (filename) {
    url += "?filename=" + filename;
}

var input = '<TEXTAREA name="kml">' + kml + '</TEXTAREA>';

//send request
jQuery('<form action="' + url + '" method="post">' + input + '</form>').appendTo('body').submit().remove();

Answer 2

以下是一些要保存的JQuery操作：

$('#saveKML').click(function() {
 var kmlFormat = new OpenLayers.Format.KML();
 var newWindow = window.open('', 
  'KML Export ' + (new Date()).getTime(), "width=300,height=300");
   newWindow.document.write('<textarea id="kml" style="width: 100%; height: 100%">' + 
   kmlFormat.write(features) + '</textarea>');
});

Answer 3

如果您使用Openlayers 3或4，您会发现之前（2012）答案的语法不再有效。

这样做：

        function GetKMLFromFeatures(features) {
            var format = new ol.format.KML();
            var kml = format.writeFeatures(features, {featureProjection: 'EPSG:3857'});
            return kml;
        }
        function GetGeoJSONFromFeatures(features) {
            var format = new ol.format.GeoJSON();
            var geoJSON = format.writeFeatures(features, {featureProjection: 'EPSG:3857'});
            return geoJSON;
        }
        function GetFeaturesFromLayer(layer) {
            var source = layer.getSource();
            var features = source.getFeatures();
            return features;
        }

Openlayers根据您的地图编写并保存KML

3 个答案:

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