Extract coordinates from KML file in Java
Following the javadocs (unofficial) you need to check - using instanceof - each Feature whether is is a Placemark, if yes cast to it and get the Geometry which itself needs to be checked whether it is a Polygon, if yes then cast to it. After that the path to the coordinates is the following (just as it come in the kml-file):
getOuterBoundaryIs > getlinearRing > getCoordinates
Here is how it looks like in code:
@Test
public void parseKml() {
String src = "misctests/stackoverflow/kml/labasa.kml";
try(InputStream is = getClass().getClassLoader().getResourceAsStream(src)) {
Assert.assertNotNull(is);
Kml kml = Kml.unmarshal(is);
Feature feature = kml.getFeature();
parseFeature(feature);
}
}
private void parseFeature(Feature feature) {
if(feature != null) {
if(feature instanceof Document) {
Document document = (Document) feature;
List<Feature> featureList = document.getFeature();
for(Feature documentFeature : featureList) {
if(documentFeature instanceof Placemark) {
Placemark placemark = (Placemark) documentFeature;
Geometry geometry = placemark.getGeometry();
parseGeometry(geometry);
}
}
}
}
}
private void parseGeometry(Geometry geometry) {
if(geometry != null) {
if(geometry instanceof Polygon) {
Polygon polygon = (Polygon) geometry;
Boundary outerBoundaryIs = polygon.getOuterBoundaryIs();
if(outerBoundaryIs != null) {
LinearRing linearRing = outerBoundaryIs.getLinearRing();
if(linearRing != null) {
List<Coordinate> coordinates = linearRing.getCoordinates();
if(coordinates != null) {
for(Coordinate coordinate : coordinates) {
parseCoordinate(coordinate);
}
}
}
}
}
}
}
private void parseCoordinate(Coordinate coordinate) {
if(coordinate != null) {
System.out.println("Longitude: " + coordinate.getLongitude());
System.out.println("Latitude : " + coordinate.getLatitude());
System.out.println("Altitude : " + coordinate.getAltitude());
System.out.println("");
}
}
With respect to A4L answer , thank you so much while i have added some more extraction methods which will get data from folder and document with point line and polygon extraction with spring MVC using javaapi4kml using package
<dependency>
<groupId>de.micromata.jak</groupId>
<artifactId>JavaAPIforKml</artifactId>
<version>2.2.0</version>
</dependency>
@RequestMapping(value = "/testKml", method = RequestMethod.POST)
public Map<String, Object> parseKml(@RequestBody Map<String, Object> data){
Map<String, Object> response = new HashMap<String, Object>();
List<Map<String, Object>> wktObjrow = new ArrayList<Map<String, Object>>();
String src = data.get("kmlfile").toString();
try {
URL url;
url = new URL(src);
URLConnection conn = url.openConnection();
InputStream is = url.openStream();
Assert.notNull(is);
Kml kml = Kml.unmarshal(is);
Feature feature = kml.getFeature();
Map<String, Object> geodata = new HashMap<String, Object>();
if(feature != null) {
if(feature instanceof Document) {
Document document = (Document) feature;
List<Feature> featureList = document.getFeature();
for(Feature documentFeature : featureList) {
if(documentFeature instanceof Placemark) {
geodata = new HashMap<String, Object>();
Placemark placemark = (Placemark) documentFeature;
Geometry geometry = placemark.getGeometry();
geodata = parseGeometry(geometry, documentFeature.getName().toString());
if(!geodata.isEmpty())
{
wktObjrow.add(geodata);
}
}
else if(documentFeature instanceof Folder)
{
Folder folder = (Folder) documentFeature;
List<Feature> folderfeaturList = folder.getFeature();
for(Feature folderfeature : folderfeaturList)
{
geodata = new HashMap<String, Object>();
if(folderfeature instanceof Placemark) {
Placemark placemark = (Placemark) folderfeature;
Geometry geometry = placemark.getGeometry();
//push each of return store in list
geodata = parseGeometry(geometry, placemark.getName().toString());
if(!geodata.isEmpty())
{
wktObjrow.add(geodata);
}
}
else
{
System.err.println("folderfeatures was not of type Placemark");
}
}
}
else
{
System.err.println("Was not instance of Placemark or Folder");
}
}
System.out.println("wktObjrow : "+wktObjrow);
}
else
{
System.err.println("instance of feature was Not Document");
if(feature instanceof Folder) {
Folder folder = (Folder) feature;
List<Feature> featureList = folder.getFeature();
geodata = new HashMap<String, Object>();
for(Feature documentFeature : featureList) {
if(documentFeature instanceof Placemark) {
Placemark placemark = (Placemark) documentFeature;
Geometry geometry = placemark.getGeometry();
if(documentFeature.getName().toString().length() > 0)
{
geodata = parseGeometry(geometry, documentFeature.getName().toString());
if(!geodata.isEmpty())
{
wktObjrow.add(geodata);
}
}
else
{
geodata = parseGeometry(geometry, placemark.getName().toString());
if(!geodata.isEmpty())
{
wktObjrow.add(geodata);
}
}
}else
{
System.err.println("Was not instance of Placemark");
}
}
System.out.println("wktObjrow : "+wktObjrow);
}
}
}
else
{
System.err.println("Feature was null");
response.put("Null", "Feature was null");
}
}
catch (Exception e) {
// TODO: handle exception
System.err.println("Exception @ : "+ e);
}
if(!wktObjrow.isEmpty() && wktObjrow != null)
{
response.put("data", wktObjrow);
}
return response;
}
public Map<String, Object> parseGeometry(Geometry geometry,String name) {
// <Point> <LinearRing> <Geometry> <Model> <LineString> <Polygon> <MultiGeometry>
Map<String, Object> response = new HashMap<String, Object>();
List<Map<String, Object>> wktObjrow = new ArrayList<Map<String, Object>>();
if(geometry != null) {
if(geometry instanceof Polygon) {
Polygon polygon = (Polygon) geometry;
Boundary outerBoundaryIs = polygon.getOuterBoundaryIs();
if(outerBoundaryIs != null) {
LinearRing linearRing = outerBoundaryIs.getLinearRing();
if(linearRing != null) {
List<Coordinate> coordinates = linearRing.getCoordinates();
if(coordinates != null) {
Map<String, Object> map = new HashMap<String, Object>();
ArrayList<String> wkt_lonlat = new ArrayList<String>();
for(Coordinate coordinate : coordinates) {
wkt_lonlat.add(coordinate.getLongitude()+" "+coordinate.getLatitude());
}
response.put("name",name);
response.put("category","POLYGON");
response.put("row","POLYGON(("+String.join(",", wkt_lonlat)+"))");
}
else
{
System.err.println("coordinate was null");
}
}
}
}
else if(geometry instanceof Point)
{
Point point = (Point) geometry;
List<Coordinate> coordinates = point.getCoordinates();
if(coordinates != null && !coordinates.isEmpty())
{
if(coordinates != null) {
for(Coordinate coordinate : coordinates) {
Map<String, Object> map = new HashMap<String, Object>();
response.put("lon",coordinate.getLongitude());
response.put("lat",coordinate.getLatitude());
response.put("name",name);
response.put("category","POINT");
}
}
}
}
else if(geometry instanceof LineString)
{
LineString line = (LineString) geometry;
List<Coordinate> coordinates = line.getCoordinates();
if(coordinates != null && !coordinates.isEmpty())
{
if(coordinates != null) {
Map<String, Object> map = new HashMap<String, Object>();
ArrayList<String> wkt_lonlat = new ArrayList<String>();
for(Coordinate coordinate : coordinates) {
wkt_lonlat.add(coordinate.getLongitude()+" "+coordinate.getLatitude());
}
response.put("name",name);
response.put("category","LINESTRING");
response.put("row","LINESTRING("+String.join(",", wkt_lonlat)+")");
}
}
}
else if(geometry instanceof MultiGeometry)
{
MultiGeometry multigeometry = (MultiGeometry) geometry;
for (int j = 0; j < multigeometry.getGeometry().size(); j++) {
if(multigeometry.getGeometry().get(j) instanceof LineString)
{
LineString line = (LineString) multigeometry.getGeometry().get(j);
List<Coordinate> coordinates = line.getCoordinates();
if(coordinates != null && !coordinates.isEmpty())
{
if(coordinates != null) {
Map<String, Object> map = new HashMap<String, Object>();
ArrayList<String> wkt_lonlat = new ArrayList<String>();
for(Coordinate coordinate : coordinates) {
wkt_lonlat.add(coordinate.getLongitude()+" "+coordinate.getLatitude());
}
response.put("name",name);
response.put("category","LINESTRING");
response.put("row","LINESTRING("+String.join(",", wkt_lonlat)+")");
}
}
}
else if(multigeometry.getGeometry().get(j) instanceof Point)
{
Point point = (Point) multigeometry.getGeometry().get(j);
List<Coordinate> coordinates = point.getCoordinates();
if(coordinates != null && !coordinates.isEmpty())
{
if(coordinates != null) {
for(Coordinate coordinate : coordinates) {
Map<String, Object> map = new HashMap<String, Object>();
response.put("lon",coordinate.getLongitude());
response.put("lat",coordinate.getLatitude());
response.put("name",name);
response.put("category","POINT");
}
}
}
}
else if(multigeometry.getGeometry().get(j) instanceof Polygon)
{
Polygon polygon = (Polygon) multigeometry.getGeometry().get(j);
Boundary outerBoundaryIs = polygon.getOuterBoundaryIs();
if(outerBoundaryIs != null) {
LinearRing linearRing = outerBoundaryIs.getLinearRing();
if(linearRing != null) {
List<Coordinate> coordinates = linearRing.getCoordinates();
if(coordinates != null) {
Map<String, Object> map = new HashMap<String, Object>();
ArrayList<String> wkt_lonlat = new ArrayList<String>();
for(Coordinate coordinate : coordinates) {
wkt_lonlat.add(coordinate.getLongitude()+" "+coordinate.getLatitude());
}
response.put("name",name);
response.put("category","POLYGON");
response.put("row","POLYGON(("+String.join(",", wkt_lonlat)+"))");
}
else
{
System.err.println("coordinate was null");
}
}
}
}
}
}
}
else
{
System.err.println("geometry was null");
response.put("Null", "geometry was null");
}
return response;
}