Using Java to generate MAPBOX-GL-readable vector tiles

Overview

MAPBOX-GL main data source from Mapbox vector tile, this article is to explain how to convert the geospatial data in PostgreSQL into vector tile, the flowchart is as follows:

Configuration

The project uses spring Boot+maven, so the first step is the Pom.xml configuration:

<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.lilei.mvt</groupid><artifactid> vector-server</artifactid><version>0.0.1-snapshot</version><packaging>jar</ Packaging><name>vector-server</name><url>http://maven.apache.org</url><parent ><groupid>org.springframework.boot</groupid><artifactid>spring-boot-starter-parent</ Artifactid><version>1.4.0.release</version><relativepath/> <!--lookup parent from Repository--></parent><repositories><repository><id>ecc</id><url>https ://github.com/electronicchartcentre/ecc-mvn-repo/raw/master/releases</url></repository></ Repositories><properties><projecT.build.sourceencoding>utf-8</project.build.sourceencoding><project.reporting.outputencoding> Utf-8</project.reporting.outputencoding><java.version>1.8</java.version></properties> <dependencies><dependency><groupid>org.springframework.boot</groupid><artifactid >spring-boot-devtools</artifactId></dependency><dependency><groupId> Org.springframework.boot</groupid><artifactid>spring-boot-starter-freemarker</artifactid> </dependency><dependency><groupid>org.webjars</groupid><artifactid>jquery</ artifactid><version>2.1.4</version></dependency><!--Database--><dependency>< groupid>org.springframework.boot</groupid><artifactid>spring-boot-starter-data-jpa</ Artifactid></dependency><dependency><groupid>org.postgresql</groupid><artifactid >postgresql</artifactid><version>42.1.1</version></dependency><dependency><groupid>org.springframework.boot</ groupid><artifactid>spring-boot-starter-test</artifactid><scope>test</scope></ dependency><dependency><groupid>com.vividsolutions</groupid><artifactid>jts</ Artifactid><version>1.13</version></dependency><dependency><groupid> com.google.protobuf</groupid><artifactid>protobuf-java</artifactid><version>2.6.1</ version></dependency><!--https://mvnrepository.com/artifact/com.google.protobuf.nano/ Protobuf-javanano--><dependency><groupid>com.google.protobuf.nano</groupid><artifactid >protobuf-javanano</artifactId><version>3.0.0-alpha-4</version></dependency>< dependency><groupid>no.ecc.vectortile</groupid><artifactid>java-vector-tile</ artifactid><version>1.2.1</version>&Lt;/dependency></dependencies><build><plugins><plugin><groupid> org.springframework.boot</groupid><artifactid>spring-boot-maven-plugin</artifactid></ Plugin></plugins></build></project>

Add the Mercator Projection transformation Tool class:

　　

Core content

Parse geographic data and convert it into vector tiles:

@Overridepublic byte[] getcontents (string type, int x, int y, int z) {String sql = Null;if (type.equals ("link")) {sql = "se Lect Link_pid,name,st_astext (Geom) as Geom from Beijing_link "+" where "+" st_intersects (Geom,st_geomfromtext (?, 4326)) " + "";} else if (type.equals ("poi")) {sql = "select Pid,st_astext (Geom) as Geom from poi5" + "where" + "st_intersects (Geom,st_geom Fromtext (?, 4326)) "+" ";} try {String tile = Tileutils.parsexyz2bound (x, y, z); List<map<string, object>> results = jdbc.queryforlist (sql, tile); Vectortileencoder VTE = new Vectortileencoder (4096, +, false); for (map<string, object> m:results) {String wkt = ( String) m.get ("Geom"); Geometry geom = new Wktreader (). read (wkt); Tileutils.convert2piexl (x, Y, Z, Geom), M.remove ("Geom"); Vte.addfeature (Type, M, Geom);} return Vte.encode ();} catch (ParseException e) {e.printstacktrace ();} return null;}

　　

GitHub Affiliate Program

The program has been uploaded to GitHub at address: HTTPS://GITHUB.COM/LILEIALG/MVT

MAPBOX-GL Post-Parse effect

Using Java to generate MAPBOX-GL-readable vector tiles