Create shapefile based on geojson data with geotools (Java)

Question

I'm using Geotools 14.0 for Java and I'm trying to generate shapefile based on data from GeoJSON. Here is my code:

try {
        String url = "geojson.json";
        File geojson = new File(url);

        File shpFile = new File("test.shp");
        ShapefileDataStoreFactory dataStoreFactory = new ShapefileDataStoreFactory();

        Map<String, Serializable> params = new HashMap<String, Serializable>();
        params.put("url", shpFile.toURI().toURL());
        params.put("create spatial index", Boolean.TRUE);

        ShapefileDataStore shpDataStore = (ShapefileDataStore) dataStoreFactory.createNewDataStore(params);

        InputStream in = new FileInputStream(geojson);
        int decimals = 15;
        GeometryJSON gjson = new GeometryJSON(decimals);
        FeatureJSON fjson = new FeatureJSON(gjson);

        FeatureCollection<SimpleFeatureType, SimpleFeature> fc = fjson.readFeatureCollection(in);

        SimpleFeatureType type = (SimpleFeatureType) fc.getSchema();

        shpDataStore.createSchema(type);
        Transaction transaction = new DefaultTransaction("create");

        String typeName = shpDataStore.getTypeNames()[0];

        SimpleFeatureSource featureSource = shpDataStore.getFeatureSource(typeName);

        if (featureSource instanceof FeatureStore) {
            SimpleFeatureStore featureStore = (SimpleFeatureStore) featureSource;

            featureStore.setTransaction(transaction);
            try {

                featureStore.addFeatures(fc);
                for(Object c : featureStore.getFeatures().toArray()){
                    System.out.println("C: " + ((SimpleFeatureImpl)c).toString());
                }
                transaction.commit();                    
            } catch (Exception ex) {
                ex.printStackTrace();
                transaction.rollback();

            } finally {
                transaction.close();
            }
        } else {
            System.out.println(typeName + " does not support read/write access");
        }
    } catch (Exception e) {
        return "Exception " + e.getLocalizedMessage();
    }

And after this, i get test.shp file but it does not contain any geometry data. If I convert it back to geojson I get this:

{   "type": "Feature",   "properties": {   },   "id": "test.1" }

And this is my original geojson file (geojson.json):

{
  "type": "FeatureCollection",
  "features": [
    {
      "properties": {
        "version": 0
      },
      "id": "1",
      "type": "Feature",
      "geometry": {
        "type": "Polygon",
        "coordinates": [
          [
            [
              1868732.467515988,
              6594375.3042187244
            ],
            [
              1868732.467515988,
              5165920.1196253505
            ],
            [
              3297187.6521093622,
              5165920.1196253505
            ],
            [
              3297187.6521093622,
              6594375.3042187244
            ],
            [
              1868732.467515988,
              6594375.3042187244
            ]
          ]
        ]
      }
    }
  ]       }

Is there any way to do this in a proper way?

Answer 1

Short answer: Your feature type doesn't match the Shapefile standard so the illegal bits get dropped by GeoTools. I have a utility class to fix this -

try {
        String url = "geojson.json";
        File geojson = new File(url);

        File shpFile = new File("test.shp");
        ShapefileDataStoreFactory dataStoreFactory = new ShapefileDataStoreFactory();

        Map<String, Serializable> params = new HashMap<String, Serializable>();
        params.put("url", shpFile.toURI().toURL());
        params.put("create spatial index", Boolean.TRUE);

        /*
         * ShapefileDataStore shpDataStore = (ShapefileDataStore)
         * dataStoreFactory.createNewDataStore(params);
         */
        InputStream in = new FileInputStream(geojson);
        int decimals = 15;
        GeometryJSON gjson = new GeometryJSON(decimals);
        FeatureJSON fjson = new FeatureJSON(gjson);

        FeatureCollection<SimpleFeatureType, SimpleFeature> fc = fjson.readFeatureCollection(in);
        fc.getSchema();

        WriteShapefile writer = new WriteShapefile(shpFile);
        writer.writeFeatures(fc);
    } catch (Exception e) {
        e.printStackTrace();

        // return "Exception " + e.getLocalizedMessage();
    }

Long answer: Shapefiles suck as a format! The first attribute in every feature must be the geometry and it must be called the_geom (hence my earlier suggestion to change the name of your geometry attribute). As featuretypes are immutable in GeoTools it is necessary to loop through the attributes and rename the geometry and then move it to first place while creating a new schema. DataUtilities.retype will reorder the attributes to match the new schema but as the geometry has changed name you have to copy the yourself. Then you can write the shapefile out as normal.