maven依賴

<geotools.version>17.1</geotools.version>
<!-- for geotools begin -->
        <dependency>
            <groupId>org.geotools</groupId>
            <artifactId>gt-geojson</artifactId>
            <version>${geotools.version}</version>
 

        </dependency>
        <!-- https://mvnrepository.com/artifact/org.geotools/gt-main -->
        <dependency>
            <groupId>org.geotools</groupId>
            <artifactId>gt-main</artifactId>
            <version>${geotools.version}</version>
 

        </dependency>
        <dependency>
            <groupId>org.geotools</groupId>
            <artifactId>gt-api</artifactId>
            <version>${geotools.version}</version>
        </dependency>
        <dependency>
            <groupId
 
>org.geotools</groupId>
            <artifactId>gt-opengis</artifactId>
            <version>${geotools.version}</version>
        </dependency>
        <dependency>
            <groupId>org.geotools</groupId>
            <artifactId>gt-data</artifactId>
            <version>${geotools.version}</version>
        </dependency>
        <dependency>
            <groupId>org.geotools</groupId>
            <artifactId>gt-referencing</artifactId>
            <version>${geotools.version}</version>
        </dependency>
        <!--for geotools end-->

引用情況

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的子類主要有Point, LineString和Polygon. 基本操作類似。所以此處以LineString為例說明

LineString–>geojson

// 由wkt字串構造LineString物件
WKTReader reader = new WKTReader( geometryFactory );
LineString lineString = (LineString)reader.read("LINESTRING (254058.76074485347 475001.2186020431, 255351.04293761664 474966.9279243938)");
// 設定保留6位小數，否則GeometryJSON預設保留4位小數
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還定義了帶屬性的Feature和表示Geometry物件集合的FeatureCollection，構造方法更加複雜，寫兩個示例備忘吧。

LineString轉Feature

// geometry是必須的，其他屬性可根據需求自定義，但是支援的型別有限，例如這個版本中double是不支援的，只支援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中宣告的順序為屬性賦值就可以，其他方法我暫未嘗試
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());

執行結果如下：

{“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轉LineString

應該與GeometryJson中的方法類似，因暫未遇到此需求，就先空著吧。隨緣。。。。

LineString轉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<SimpleFeature> 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());

列印結果如下：

{“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”}]}

對於FeatureCollection中包含不同型別Geometry物件的情況，等遇到再研究吧。