java GeoPackage

Java GeoPackage是在OGC OWS-10测试平台下开发的一个Java库和客户端，用于创建、插入、查询和更新SQLite数据库中的记录。它可以通过直接编写代码或使用SimpleFeature和SimpleFeatureType接口来操作数据库。Java GeoPackage客户端适用于各种地理空间应用，并且可以在其上进行扩展和定制。

以下是一个使用Java GeoPackage库创建和查询记录的示例：

import org.geotools.data.DataStore;
import org.geotools.data.DataStoreFinder;
import org.geotools.data.simple.SimpleFeatureSource;
import org.geotools.feature.simple.SimpleFeatureTypeBuilder;
import org.geotools.feature.simple.SimpleFeatureBuilder;
import org.opengis.feature.simple.SimpleFeature;
import org.opengis.feature.simple.SimpleFeatureType;

import java.io.File;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;

public class GeoPackageExample {
    public static void main(String[] args) {
        // 创建GeoPackage文件
        File file = new File("example.gpkg");

        // 设置GeoPackage参数
        Map<String, Object> params = new HashMap<>();
        params.put("dbtype", "geopkg");
        params.put("database", file);

        try {
            // 创建GeoPackage数据存储
            DataStore dataStore = DataStoreFinder.getDataStore(params);

            // 创建要素类型
            SimpleFeatureTypeBuilder typeBuilder = new SimpleFeatureTypeBuilder();
            typeBuilder.setName("Example");
            typeBuilder.add("name", String.class);
            typeBuilder.add("population", Integer.class);
            SimpleFeatureType featureType = typeBuilder.buildFeatureType();

            // 创建要素
            SimpleFeatureBuilder featureBuilder = new SimpleFeatureBuilder(featureType);
            featureBuilder.add("City A");
            featureBuilder.add(1000000);
            SimpleFeature feature = featureBuilder.buildFeature(null);

            // 插入要素
            dataStore.createSchema(featureType);
            dataStore.getFeatureSource("Example").addFeatures(DataUtilities.collection(feature));

            // 查询要素
            SimpleFeatureSource featureSource = dataStore.getFeatureSource("Example");
            Filter filter = CQL.toFilter("population > 500000");
            FeatureCollection<SimpleFeatureType, SimpleFeature> features = featureSource.getFeatures(filter);
            try (FeatureIterator<SimpleFeature> iterator = features.features()) {
                while (iterator.hasNext()) {
                    SimpleFeature resultFeature = iterator.next();
                    System.out.println(resultFeature.getAttribute("name"));
                }
            }

            // 关闭数据存储
            dataStore.dispose();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

这个示例演示了如何使用Java GeoPackage库创建一个名为"Example"的要素类型，并向其中插入一条记录。然后，通过查询获取人口超过500,000的城市名称。