使用java生成mapbox-gl可读的vector tile

Posted 2020-10-14 李雷

概述

mapbox-gl主要数据源来自mapbox vector tile，本文就是要阐述怎样把postgresql中的地理空间数据转换成vector tile，流程图如下：

 

配置

该工程采用spring boot+maven，所以第一步少不了pom.xml配置：

<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>

		<!-- 数据库 -->
		<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>
		</dependency>

	</dependencies>

	<build>
		<plugins>
			<plugin>
				<groupId>org.springframework.boot</groupId>
				<artifactId>spring-boot-maven-plugin</artifactId>
			</plugin>
		</plugins>
	</build>


</project>

添加墨卡托投影转换工具类：

 

　　

核心内容

解析地理数据，转换成vector tile：

@Override
	public byte[] getContents(String type, int x, int y, int z) {
		
		String sql = null;
		
		if (type.equals("link")){
			sql = "select 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_geomfromtext(?,4326)) "
							+ "";
		}
		

		try {

			String tile = TileUtils.parseXyz2Bound(x, y, z);
			
			List<Map<String, Object>> results = jdbc.queryForList(sql, tile);

			VectorTileEncoder vte = new VectorTileEncoder(4096, 16, 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关联程序

程序已上传github，地址为：https://github.com/lileialg/mvt

mapbox-gl解析后效果