RegionsApplication.kt

package com.regions

import org.geotools.geojson.feature.FeatureJSON
import org.geotools.geometry.jts.JTS
import org.geotools.referencing.CRS
import org.locationtech.jts.geom.Polygon
import org.slf4j.LoggerFactory
import org.springframework.boot.autoconfigure.SpringBootApplication
import org.springframework.boot.runApplication
import org.springframework.scheduling.annotation.EnableScheduling
import org.springframework.scheduling.annotation.Scheduled
import org.springframework.stereotype.Component
import java.nio.charset.StandardCharsets

@Component
class RegionStuff {

    private val log = LoggerFactory.getLogger(this::class.java)

    @Scheduled(fixedRateString = "1000")
    fun testRegion() {
        val json = FeatureJSON()
        val geojsonString =
            "{\"type\":\"FeatureCollection\",\"features\":[{\"type\":\"Feature\",\"properties\":{},\"geometry\":{\"type\":\"Polygon\",\"coordinates\":[[[-162.1,69.5],[-111.8,46.8],[-71.4,69.5],[-162.1,69.5]]]}}]}"
        val featureCollection = json.readFeatureCollection(
            geojsonString.byteInputStream(StandardCharsets.UTF_8)
        )
        assert(featureCollection.size() == 1)

        val polygon = featureCollection.features().next().defaultGeometryProperty.value as Polygon

        // Project WGS84 to UTM
        val sourceCrs = CRS.decode("EPSG:4326", true)
        val targetCrs = if (CRS.getAxisOrder(sourceCrs) == CRS.AxisOrder.EAST_NORTH) {
            CRS.decode("AUTO:42001,${polygon.centroid.x},${polygon.centroid.y}")
        } else {
            CRS.decode("AUTO:42001,${polygon.centroid.y},${polygon.centroid.x}")
        }
        val transform = CRS.findMathTransform(sourceCrs, targetCrs)
        val projectedPolygon = JTS.transform(polygon, transform) as Polygon

        log.info("original  $polygon")
        log.info("projected $projectedPolygon")
        log.info("original-area  ${polygon.area}")
        log.info("projected-area ${projectedPolygon.area}")
    }
}

@SpringBootApplication
@EnableScheduling
class RegionsApplication

fun main(args: Array<String>) {
    runApplication<RegionsApplication>(*args)
}