Geotools中Geometry对象与GeoJson的相互转换

maven依赖

<geotools.version>17.1geotools.version>

        <dependency>
            <groupId>org.geotoolsgroupId>
            <artifactId>gt-geojsonartifactId>
            <version>${geotools.version}version>
        dependency>
        
        <dependency>
            <groupId>org.geotoolsgroupId>
            <artifactId>gt-mainartifactId>
            <version>${geotools.version}version>
        dependency>
        <dependency>
            <groupId>org.geotoolsgroupId>
            <artifactId>gt-apiartifactId>
            <version>${geotools.version}version>
        dependency>
        <dependency>
            <groupId>org.geotoolsgroupId>
            <artifactId>gt-opengisartifactId>
            <version>${geotools.version}version>
        dependency>
        <dependency>
            <groupId>org.geotoolsgroupId>
            <artifactId>gt-dataartifactId>
            <version>${geotools.version}version>
        dependency>
        <dependency>
            <groupId>org.geotoolsgroupId>
            <artifactId>gt-referencingartifactId>
            <version>${geotools.version}version>
        dependency>
        

引用情况

import com.fasterxml.jackson.databind.ObjectMapper;
import com.vividsolutions.jts.geom.*;
import com.vividsolutions.jts.geom.Point;
import com.vividsolutions.jts.io.ParseException;
import com.vividsolutions.jts.io.WKTReader;
import com.vividsolutions.jts.operation.linemerge.LineMerger;
import org.geotools.data.DataUtilities;
import org.geotools.feature.SchemaException;
import org.geotools.feature.simple.SimpleFeatureBuilder;
import org.geotools.geojson.feature.FeatureJSON;
import org.geotools.geojson.geom.GeometryJSON;
import org.geotools.geometry.jts.JTSFactoryFinder;
import org.opengis.feature.simple.SimpleFeature;
import org.opengis.feature.simple.SimpleFeatureType;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
import org.springframework.util.StringUtils;

import java.io.IOException;
import java.io.StringReader;
import java.io.StringWriter;
import java.util.*;

Geometry的子类主要有Point, LineString和Polygon. 基本操作类似。所以此处以LineString为例说明

LineString–>geojson

// 由wkt字符串构造LineString对象
WKTReader reader = new WKTReader( geometryFactory );
LineString lineString = (LineString)reader.read("LINESTRING (254058.76074485347 475001.2186020431, 255351.04293761664 474966.9279243938)");
// 设置保留6位小数，否则GeometryJSON默认保留4位小数
GeometryJSON geometryJson = new GeometryJSON(6);
StringWriter writer = new StringWriter();
geometryJson.write(lineString, writer);
System.out.println(writer.toString());
writer.close();

geojson–>LineString

LineString lineString = (LineString) geometryJson.read(new StringReader("{\n" +
                "                \"type\": \"LineString\",\n" +
                "                \"coordinates\": [\n" +
                "                    [\n" +
                "                        120.6584555,\n" +
                "                        30.45144\n" +
                "                    ],\n" +
                "                    [\n" +
                "                        120.1654515,\n" +
                "                        30.54848\n" +
                "                    ]\n" +
                "                ]\n" +
                "            }"));

geojson还定义了带属性的Feature和表示Geometry对象集合的FeatureCollection，构造方法更加复杂，写两个示例备忘吧。

LineString转Feature

// geometry是必须的，其他属性可根据需求自定义，但是支持的类型有限，例如这个版本中double是不支持的，只支持float
final SimpleFeatureType TYPE = DataUtilities.createType("Link",
                "geometry:LineString," + // <- the geometry attribute: Point type
                        "gid:String," +   // <- a String attribute
                        "direction:Integer," +   // a number attribute
                        "orientation:Integer"
        );
SimpleFeatureBuilder featureBuilder = new SimpleFeatureBuilder(TYPE);
GeometryFactory geometryFactory = JTSFactoryFinder.getGeometryFactory();
WKTReader reader = new WKTReader( geometryFactory );
FeatureJSON fjson = new FeatureJSON();
LineString lineString = (LineString)reader.read("LINESTRING (254058.76074485347 475001.2186020431, 255351.04293761664 474966.9279243938)");
// 按照TYPE中声明的顺序为属性赋值就可以，其他方法我暂未尝试
featureBuilder.add(lineString);
featureBuilder.add("123456");
featureBuilder.add(2);
featureBuilder.add(0);
SimpleFeature feature = featureBuilder.buildFeature(null);
StringWriter writer = new StringWriter();
fjson.writeFeature(feature, writer);
System.out.println(writer.toString());

执行结果如下：

{“type”:”Feature”,”geometry”:{“type”:”LineString”,”coordinates”:[[254058.7607,475001.2186],[255351.0429,474966.9279]]},”properties”:{“gid”:”123456”,”direction”:2,”orientation”:0},”id”:”fid–5b8f258_15e04bda4b8_-8000”}

Feature转LineString

应该与GeometryJson中的方法类似，因暂未遇到此需求，就先空着吧。随缘。。。。

LineString转FeatureCollection

String[] WKTS = { "LINESTRING (255351.04293761664 474966.9279243938, 255529.29662365236 474272.4599921228)",
                "LINESTRING (255529.29662365236 474272.4599921228, 256166.05830998957 473979.44920198264)"};
final SimpleFeatureType TYPE = DataUtilities.createType("Link",
                "geometry:LineString," + // <- the geometry attribute: Point type
                        "gid:String," +   // <- a String attribute
                        "direction:Integer," +   // a number attribute
                        "orientation:Integer"
);
SimpleFeatureBuilder featureBuilder = new SimpleFeatureBuilder(TYPE);
GeometryFactory geometryFactory = JTSFactoryFinder.getGeometryFactory();
WKTReader reader = new WKTReader( geometryFactory );
FeatureJSON fjson = new FeatureJSON();
List features = new ArrayList<>();
SimpleFeatureCollection collection = new ListFeatureCollection(TYPE, features);
for (String wkt : WKTS) {
    LineString lineString = (LineString)reader.read(wkt);
    featureBuilder.add(lineString);
    featureBuilder.add("123456");
    featureBuilder.add(2);
    featureBuilder.add(1);
    SimpleFeature feature = featureBuilder.buildFeature(null);
    features.add(feature);
}
StringWriter writer = new StringWriter();
fjson.writeFeatureCollection(collection, writer);
System.out.println(writer.toString());

打印结果如下：

{“type”:”FeatureCollection”,”features”:[{“type”:”Feature”,”geometry”:{“type”:”LineString”,”coordinates”:[[255351.0429,474966.9279],[255529.2966,474272.46]]},”properties”:{“gid”:”123456”,”direction”:2,”orientation”:1},”id”:”fid-67c46b85_15e0778dd81_-8000”},{“type”:”Feature”,”geometry”:{“type”:”LineString”,”coordinates”:[[255529.2966,474272.46],[256166.0583,473979.4492]]},”properties”:{“gid”:”123456”,”direction”:2,”orientation”:1},”id”:”fid-67c46b85_15e0778dd81_-7fff”}]}

对于FeatureCollection中包含不同类型Geometry对象的情况，等遇到再研究吧。