【JSON】GeoJson和普通Json的使用

普通JSON

fastJson依赖

<!-- https://mvnrepository.com/artifact/com.alibaba/fastjson -->
<dependency>
   <groupId>com.alibaba</groupId>
   <artifactId>fastjson</artifactId>
   <version>1.2.73</version>
</dependency>

对象转Json

String s = JSON.toJSONString(obj);

解析Json字符串，获取值

JSONObject json= JSON.parseObject(geoJson);
Object where = json.get("name");

GeoJson

GeoJson转换Feature、FutureCollection

/**
     * 解析单个feature的geojson
     * @param geojson
     * @param geoSRS
     * @return
     * @throws IOException
     * @throws FactoryException
     */
    public static SimpleFeature jsonToFeature(String geojson,String geoSRS) throws IOException, FactoryException {
        //设置精度为15位
        FeatureJSON featureJSON = new FeatureJSON(new GeometryJSON(2));
        SimpleFeature simpleFeature = featureJSON.readFeature(geojson);
        //解决geojson的geometry定义的问题
        SimpleFeatureType newType = retype(simpleFeature.getFeatureType(),geoSRS);
        SimpleFeature newFeature = retypeFeature(simpleFeature,newType);
        return newFeature;
    }


    /**
     * 解析多个feature的geojson
     * @param geojson
     * @param geoSRS
     * @return
     * @throws IOException
     * @throws FactoryException
     * @throws SchemaException
     */
    public static FeatureCollection jsonToCollection(String geojson,String geoSRS) throws IOException, FactoryException, SchemaException {
        //设置精度为15位
        FeatureJSON featureJSON = new FeatureJSON(new GeometryJSON(2));
        // 读取为FeatureCollection
        FeatureCollection featureCollection = featureJSON.readFeatureCollection(geojson);
        // 获取SimpleFeatureType
        SimpleFeatureType simpleFeatureType = (SimpleFeatureType) featureCollection.getSchema();
        String srs = null;

        //如果有坐标系，转换坐标系的经纬度
        if(geoSRS != null){
            srs = geoSRS;
        } else if(simpleFeatureType.getCoordinateReferenceSystem() != null) {
            srs = CRS.lookupIdentifier(simpleFeatureType.getCoordinateReferenceSystem(),true);
            featureCollection = new ForceCoordinateSystemFeatureResults(featureCollection, CRS.decode(srs, true));
        }

        //解决geojson的geometry定义的问题
        SimpleFeatureType newType = retype(simpleFeatureType,geoSRS);
        //变换feature的type
        FeatureCollection listFeatureCollection = new ListFeatureCollection(newType);
        SimpleFeatureIterator iterator = (SimpleFeatureIterator) featureCollection.features();
        while (iterator.hasNext()){
            SimpleFeature newFeature = retypeFeature(iterator.next(),newType);
            ((ListFeatureCollection)listFeatureCollection).add(newFeature);
        }
        iterator.close();
        listFeatureCollection=new ForceCoordinateSystemFeatureResults(listFeatureCollection, CRS.decode(srs, true));
        return listFeatureCollection;
    }

Feature/Collection转GeoJson

public static String FeatureToJson(SimpleFeature simpleFeature) throws IOException {
    FeatureJSON featureJSON=new FeatureJSON();
    return featureJSON.toString(simpleFeature);
}

public static String FeatureCollectionToJson(SimpleFeatureCollection collection) throws IOException {
    FeatureJSON featureJSON=new FeatureJSON();
    return featureJSON.toString(collection);
}