GeoJson的生成与解析
环境
gt-geojson-14.2.jar，json-simple-1.1.1.jar，jts-1.8.jar
一、wkt格式的geometry转成json格式
public String evaluate(String wkt) {
String ret = null;
try {
Geometry geometry = reader.read(wkt);
StringWriter writer = new StringWriter();
GeometryJSON g = new GeometryJSON();
g.write(geometry, writer);
ret = writer.toString();
} catch (Exception e) {
LOGGER.error(e.getMessage(), e);
}
return ret;
}
二、json格式转wkt格式
public String evaluate(String geoJson) {
String ret = null;
GeometryJSON gjson = new GeometryJSON();
Reader reader = new StringReader(geoJson);
try {
Geometry geometry = gjson.read(reader);
ret = geometry.toText();
} catch (IOException e) {
LOGGER.error(e.getMessage(), e);
}
return ret;
}
三、json格式的数据进行解析
数据格式如下：
{
"_id" : "b454e650cb1a4fa4a2f2bd6899fbfa73",
"bb" : "116.2451019,39.8486099,116.2451019,39.8486099",
"pts" : [{
"1" : 0,
"2" : 39.8486099,
"3" : 116.2451019,
"4" : 0.0,
"5" : 0.0,
"6" : "2012-03-07 14:25:08",
"7" : "2012-03-07 14:25:10",
"8" : "2",
"9" : 0.0,
"10" : 1
}, {
"1" : 1,
"2" : 39.8486099,
"3" : 116.2451019,
"4" : 0.0,
"5" : 0.0,
"6" : "2012-03-07 14:25:16",
"7" : "2012-03-07 14:25:17",
"8" : "1",
"9" : 0.0,
"10" : 1
}, {
"1" : 2,
"2" : 39.8486099,
"3" : 116.2451019,
"4" : -1.0,
"5" : 0.0,
"6" : "2012-03-07 14:25:18",
"7" : "2012-03-07 14:25:20",
"8" : "1",
"9" : 0.0,
"10" : 1
}]
}
获取“_id”值和“bb”属性值（两点的经纬度坐标），获取“pts”属性中第一个标签6的值（起始时间）和最后一个标签7的属性值（终止时间），并根据经纬度计算两点之间的距离，根据起始时间和终止时间计算其时间差，得到每个“_id”的对应的距离和时间差
private final double PI = 3.1415926; //圆周率
private final static double earthRadius = 6371; //地球半径，单位为KM
public static void parseJson(BufferedReader bufferedReader)
throws IOException, ParseException, java.text.ParseException{
String line = ""; //一行一行的形式读取文件
String[] pts6FirstTime =null;//第一个坐标点标签6的时间
String pts6Time ="";
String ptsTime7 = "";
String reslut = ""; //计算最终结果
double betweenTime = 0.0d;//轨迹点之间的时间差，以小时（h）为单位
//longitude1、longitude2、dimension1、dimension2分别为经度坐标和维度坐标
double longitude1 = 0.0d;
double dimension1 = 0.0d;
double longitude2 = 0.0d;
double dimension2 = 0.0d;
//设置时间格式
DateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
//创建json解析对象
JSONParser jsonParser = new JSONParser();
//创建一个distanceAndTime对象
DistanceAndTime distanceAndTime = new DistanceAndTime();
while((line = bufferedReader.readLine())!=null){
//开始解析
JSONObject jsonObject = (JSONObject)jsonParser.parse(line);
String _id = (String) jsonObject.get("_id");//得到轨迹的id号
String bb = (String) jsonObject.get("bb");//得到轨迹的经纬度坐标bb
//经纬度坐标是以","进行分割的
String[] longitudeDismension = bb.split(",");
//Double.valueOf()把string类型转换为double类型
longitude1 = Double.valueOf(longitudeDismension[0]);
dimension1 = Double.valueOf(longitudeDismension[1]);
longitude2 = Double.valueOf(longitudeDismension[2]);
dimension2 = Double.valueOf(longitudeDismension[3]);
//计算具有经纬度的两坐标间的距离
double bbDistance = distanceAndTime.
getDistance(longitude1, dimension1, longitude2, dimension2);
//解析pts中的内容
JSONArray ptsjsonArray = (JSONArray)jsonObject.get("pts");
Iterator iterator = ptsjsonArray.iterator();
//解析pts中标签6的内容，并得到第一个标签6的内容
while(iterator.hasNext()){
JSONObject pts6JSONObject = (JSONObject)iterator.next();
pts6Time = pts6JSONObject.get("6").toString();
pts6FirstTime = pts6Time.split("
");
break;//对于标签6的时间，只要第一个时间
}
//解析pts中标签7的内容，并得到最后一个标签7的内容
while(iterator.hasNext()){
JSONObject pts7jsonobject = (JSONObject)iterator.next();
ptsTime7 = pts7jsonobject.get("7").toString();
}
//计算轨迹的时间差，单位为小时（H）
Date date1 = dateFormat.parse(ptsTime7);
Date date2 = dateFormat.parse(pts6FirstTime[0]);
betweenTime = (date1.getTime()-date2.getTime())/1000.0/3600.0;
reslut = _id+" "+bbDistance+" "+betweenTime;
writeToLocal(reslut);
// System.out.println(reslut);
}
}
//已知经纬度的轨迹点，计算两个轨迹点之间的距离，单位为KM
public double getDistance(double longitude1,double dimension1,double longitude2,double dimension2){
double x,y,distance;
x = (longitude1 - longitude2)*PI*earthRadius*
Math.cos(((dimension1+dimension2)/2)*PI/180)/180;
y = (dimension1-dimension2)*PI*earthRadius/180;
distance = Math.hypot(x, y);
return distance;
}
//计算结果输出
public static void writeToLocal(String string) throws IOException{
File outFile = new File("D://0820--Study//轨迹点数据//result.json");
if (!outFile.exists()) {
outFile.createNewFile();
}
//FileOutputStream设置为true，是为了后一条结果记录覆盖前一条结果记录
FileOutputStream fileOutputStream = new FileOutputStream(outFile,true);
OutputStreamWriter outputStreamWriter = new OutputStreamWriter(fileOutputStream);
BufferedWriter bufferedWriter = new BufferedWriter(outputStreamWriter);
bufferedWriter.write(string);
bufferedWriter.newLine();
bufferedWriter.flush();
bufferedWriter.close();
outputStreamWriter.close();
fileOutputStream.close();
}
四、Java读写geojson
/** 读 **/
public Map<Integer, SiteEntity> getSiteMap() {
Map<Integer, SiteEntity> map = new HashMap<Integer, SiteEntity>();
URL dataUrl = this.getClass().getClassLoader().getResource("public\station.json"); // 259
try{
BufferedReader br =new BufferedReader(new FileReader(new File(dataUrl.toURI())));
String s = null;
while((s = br.readLine()) != null){ // s 为原生的json串
// System.out.println("00=="+s);
JSONObject jo = new JSONObject(s); // 创建一个包含原始json串的json对象
JSONArray features = jo.getJSONArray("features"); //找到features的json数组
for (int i = 0; i < features.length(); i++) {
SiteEntity siteEntity = new SiteEntity();
JSONObject info = features.getJSONObject(i); // 获得features的第i个对象
JSONObject geometry = info.getJSONObject("geometry");
JSONObject properties = info.getJSONObject("properties");
siteEntity.setSite_stano(properties.getString("stano")); // 获得站名
List list = geometry.getJSONArray("coordinates").toList(); // 获得经纬度
siteEntity.setSite_longitude(Double.parseDouble(list.get(0).toString()));
siteEntity.setSite_latitude(Double.parseDouble(list.get(1).toString()));
// System.out.println(siteEntity.getSite_longitude()+"
"+siteEntity.getSite_latitude());
map.put(i,siteEntity);
}
}
}catch (Exception e){
e.printStackTrace();
}
return map;
}
/**写**/
public void jsonOutPut(Map map) {
ObjectMapper mapper = new ObjectMapper();
try{
mapper.writeValue(new File("D:/river-site.json"), map);
}catch (Exception e){
e.printStackTrace();
}
}
五、geotools读取shp文件
5.1 pom.xml
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.jjxliu.geotools</groupId>
<artifactId>geotools_t1</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>
<name>geotools_t1</name>
<url>http://maven.apache.org</url>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<geotools.version>20-SNAPSHOT</geotools.version>
</properties>
<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.11</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.geotools</groupId>
<artifactId>gt-shapefile</artifactId>
<version>${geotools.version}</version>
</dependency>
<dependency>
<groupId>org.geotools</groupId>
<artifactId>gt-swing</artifactId>
<version>${geotools.version}</version>
</dependency>
<dependency>
<groupId>org.geotools</groupId>
<artifactId>gt-jdbc</artifactId>
<version>${geotools.version}</version>
</dependency>
<dependency>
<groupId>org.geotools.jdbc</groupId>
<artifactId>gt-jdbc-postgis</artifactId>
<version>${geotools.version}</version>
</dependency>
<dependency>
<groupId>org.geotools</groupId>
<artifactId>gt-epsg-hsql</artifactId>
<version>${geotools.version}</version>
</dependency>
</dependencies>
<repositories>
<repository>
<id>maven2-repository.dev.java.net</id>
<name>Java.net repository</name>
<url>http://download.java.net/maven/2</url>
</repository>
<repository>
<id>osgeo</id>
<name>Open Source Geospatial Foundation Repository</name>
<url>http://download.osgeo.org/webdav/geotools/</url>
</repository>
<repository>
<snapshots>
<enabled>true</enabled>
</snapshots>
<id>boundless</id>
<name>Boundless Maven Repository</name>
<url>http://repo.boundlessgeo.com/main</url>
</repository>
</repositories>
<build>
<plugins>
<plugin>
<inherited>true</inherited>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<configuration>
<source>1.8</source>
<target>1.8</target>
</configuration>
</plugin>
</plugins>
</build>
</project>
5.2 读取shp文件
public static SimpleFeatureCollection readShp(String path ){
return readShp(path, null);
}
public static SimpleFeatureCollection readShp(String path , Filter filter){
SimpleFeatureSource featureSource = readStoreByShp(path);
if(featureSource == null) return null;
try {
return filter != null ? featureSource.getFeatures(filter) : featureSource.getFeatures() ;
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return null ;
}
public static SimpleFeatureSource readStoreByShp(String path ){
File file = new File(path);
FileDataStore store;
SimpleFeatureSource featureSource = null;
try {
store = FileDataStoreFinder.getDataStore(file);
((ShapefileDataStore) store).setCharset(Charset.forName("UTF-8"));
featureSource = store.getFeatureSource();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return featureSource ;
}
测试一段读取的代码，打印所有读取到的simplefeature
String path1 = "G:/work/china_map/shp/BOUNT_poly.shp" ;
//读取shp
SimpleFeatureCollection colls1 = readShp(path1);
//拿到所有features
SimpleFeatureIterator iters = colls1.features();
//遍历打印
while(iters.hasNext()){
SimpleFeature sf = iters.next();
System.out.println(sf.getID() + " , " + sf.getAttributes());
}
六、Geotools中Geometry对象与GeoJson的相互转换
6.1 pom.xml
<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-->
import包
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：
6.2 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();
6.3 geojson–>LineString
LineString lineString = (LineString) geometryJson.read(new StringReader("{
" +
" "type": "LineString",
" +
" "coordinates": [
" +
" [
" +
" 120.6584555,
" +
" 30.45144
" +
" ],
" +
" [
" +
" 120.1654515,
" +
" 30.54848
" +
" ]
" +
" ]
" +
" }"));
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。
6.4 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”}
6.5 Feature转LineString
6.6 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<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());
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”}]}