GIS动态矢量切片

前言

有关矢量切片以及MVT(MapBox Vector Tile)自行搜索了解，不再赘述。

接口格式http://domain:port/map/vector/tile/{z}/{x}/{y}，其中z代表缩放层级，x、y代表当前行列号

一、方法

采用postgis的函数ST_AsMVT、ST_AsMVTGeom、ST_TileEnvelope函数，实现此功能。

简单讲ST_TileEnvelope函数用于计算行列并返回对应的矩形范围，ST_AsMVTGeom返回图层中对应行的坐标，ST_AsMVT返回二进制的Mapbox Vector Tile数据。

函数解释

ST_AsMVT：返回一个二进制Mapbox Vector Tile

二、环境

Postresql 12.x + Postgis + Spring Boot

三、实现

MapBoxVectorTile

package com.osgeo.vectortile.domain;import lombok.Data;@Datapublic class MapBoxVectorTile {private byte[] tile;}

MapBoxVectorTileMapper

package com.osgeo.vectortile.mapper;import com.baomidou.mybatisplus.annotation.SqlParser;import com.osgeo.vectortile.domain.MapBoxVectorTile;import org.apache.ibatis.annotations.Mapper;import org.apache.ibatis.annotations.Param;@Mapperpublic interface MapBoxVectorTileMapper {@SqlParser(filter=true)MapBoxVectorTile vectorTitle2(@Param("z") Integer z, @Param("x") Integer x, @Param("y") Integer y, @Param("dpi") Integer dpi);}

MapBoxVectorTileMapper.xml

<?xml version="1.0" encoding="UTF-8" ?><!DOCTYPE mapperPUBLIC "-////DTD Mapper 3.0//EN""/dtd/mybatis-3-mapper.dtd"><mapper namespace="com.osgeo.vectortile.mapper.MapBoxVectorTileMapper"><resultMap type="com.osgeo.vectortile.domain.MapBoxVectorTile" id="MapBoxVectorTileResult"><result property="tile" column="tile"/></resultMap><select id="vectorTitle2" resultMap="MapBoxVectorTileResult">SELECT ST_AsMVT(tiletable.*, 'gb_title', #{dpi}) as tileFROM (SELECT id,project_name as name,approval_year as "year",build_address as poi,dept_id as dept,ST_AsMVTGeom(geo_rangeline, ST_Transform(ST_TileEnvelope(#{z}, #{x}, #{y}), 4326), #{dpi}) as geomfrom (select *from gbt_project_infowhere 1 = 1and ST_Intersects(ST_Transform(ST_TileEnvelope(#{z}, #{x}, #{y}), 4326),geo_rangeline)) ta) as tiletablewhere tiletable.geom is not null;</select></mapper>

MapBoxVectorTileServiceImpl

package com.osgeo.vectortile.service.impl;import com.osgeo.vectortile.mapper.MapBoxVectorTileMapper;import com.osgeo.vectortile.service.MapBoxVectorTileService;import com.osgeo.vectortile.utils.MapBoxVectorTileUtil;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.stereotype.Service;@Servicepublic class MapBoxVectorTileServiceImpl implements MapBoxVectorTileService {@AutowiredMapBoxVectorTileMapper mapper;@Overridepublic byte[] vectorTitle(Integer z, Integer x, Integer y) {Integer dpi = MapBoxVectorTileUtil.zoom2dpi(z);return mapper.vectorTitle2(z, x, y, dpi).getTile();}}

package com.osgeo.vectortile.utils;import com.osgeo.vectortile.domain.TileBox;import java.util.HashMap;import java.util.Map;public class MapBoxVectorTileUtil {private static Map<Integer, Integer> map;static {map = new HashMap<>();map.put(1, 2);map.put(2, 2);map.put(3, 2);map.put(5, 2);map.put(6, 2);map.put(7, 512);map.put(8, 512);map.put(9, 1024);map.put(10, 1024);map.put(11, 1024);map.put(12, 1024);map.put(13, 2048);map.put(14, 2048);map.put(15, 4096);map.put(16, 4096);map.put(17, 4096);map.put(18, 4096);map.put(19, 4096);map.put(20, 4096);}public static Integer zoom2dpi(Integer z) {return map.containsKey(z) ? map.get(z) : 2048;}}

MapBoxVectorTileService

package com.osgeo.vectortile.service;public interface MapBoxVectorTileService {byte[] vectorTitle(Integer z, Integer x, Integer y);}

MapBoxVectorTileController

package com.osgeo.vectortile.controller;import com.osgeo.vectortile.service.MapBoxVectorTileService;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.web.bind.annotation.GetMapping;import org.springframework.web.bind.annotation.PathVariable;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.RestController;import javax.servlet.http.HttpServletResponse;import java.io.*;@RestController@RequestMapping("/map/vector/tile")public class MapBoxVectorTileController {@AutowiredMapBoxVectorTileService service;@GetMapping("/new/{z}/{x}/{y}")public void vectorTitle2(@PathVariable("z")Integer z, @PathVariable("x") Integer x, @PathVariable("y") Integer y, HttpServletResponse response){response.setContentType("application/x-protobuf;type=mapbox-vector;chartset=UTF-8");byte[] tile = service.vectorTitle2(z, x, y);// 输出文件流OutputStream os = null;InputStream is = null;try {is = new ByteArrayInputStream(tile);os = response.getOutputStream();byte[] bytes = new byte[1024];int len;while ((len = is.read(bytes)) != -1) {os.write(bytes, 0, len);}os.flush();} catch (FileNotFoundException e) {e.printStackTrace();} catch (IOException e) {e.printStackTrace();} finally {try {is.close();os.close();} catch (IOException e) {e.printStackTrace();}}}}