基于 Java 与 Leaflet 的湖南省道路长度 WebGIS 系统构建

2. Mapper 空间检索查询

在 Mapper 接口中直接定义 SQL 片段，支持按省份代码聚合统计各地市路网长度：

package com.yelang.project.extend.earthquake.mapper;

import java.util.List;
import org.apache.ibatis.annotations.Param;
import org.apache.ibatis.annotations.Select;
import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.yelang.project.extend.earthquake.domain.UrbanRoadMileageInfo;
import com.yelang.project.extend.earthquake.domain.UrbanRoadMileageInfoVO;

public interface UrbanRoadMileageInfoMapper extends BaseMapper<UrbanRoadMileageInfo> {

    /**
     * 查询省级以下地市路网长度 SQL
     */
    static final String LIST_BYPROVINCE_SQL = "SELECT t1.city_code, MAX(t1.city_name) AS city_name," +
        " SUM(CASE WHEN r.fclass IN ('motorway', 'motorway_link') THEN ST_Length(r.geom::geography) ELSE 0 END) AS highway_length, " +
        " SUM(CASE WHEN r.fclass IN ('trunk', 'trunk_link') THEN ST_Length(r.geom::geography) ELSE 0 END) AS trunk_length, " +
        " SUM(CASE WHEN r.fclass IN ('primary', 'primary_link') THEN ST_Length(r.geom::geography) ELSE 0 END) AS primary_length, " +
        " SUM(CASE WHEN r.fclass IN ('secondary', 'secondary_link') THEN ST_Length(r.geom::geography) ELSE 0 END) AS secondary_length," +
        " SUM(CASE WHEN r.fclass IN ('tertiary', 'tertiary_link') THEN ST_Length(r.geom::geography) ELSE 0 END) AS tertiary_length, " +
        " SUM(CASE WHEN r.fclass IN ('residential', 'living_street') THEN ST_Length(r.geom::geography) ELSE 0 END) AS residential_length, " +
        " SUM(CASE WHEN r.fclass IN ('service', 'unclassified') THEN ST_Length(r.geom::geography) ELSE 0 END) AS service_length, " +
        " SUM(CASE WHEN r.fclass IN ('footway', 'pedestrian', 'path') THEN ST_Length(r.geom::geography) ELSE 0 END) AS pedestrian_length, " +
        " SUM(CASE WHEN r.fclass = 'cycleway' THEN ST_Length(r.geom::geography) ELSE 0 END) AS cycleway_length, " +
        " SUM(CASE WHEN r.fclass = 'track' THEN ST_Length(r.geom::geography) ELSE 0 END) AS track_length," +
        " SUM(CASE WHEN r.fclass in ('steps', 'footway') THEN ST_Length(r.geom::geography) ELSE 0 END) AS steps_length," +
        " SUM(ST_Length(r.geom::geography)) AS total_length " +
        " FROM biz_road_network r JOIN biz_city t1 ON ST_Contains(t1.geom, r.geom) WHERE t1.province_code = #{province_code} " +
        " GROUP BY t1.city_code ORDER BY total_length DESC ";

    @Select(LIST_BYPROVINCE_SQL)
    List<UrbanRoadMileageInfo> getListByProvinceCode(@Param("province_code") String provinceCode);

    final static String GET_ROADMILEAGELIST_BY_PROVINCECODE = "<script>" +
        " SELECT t1.*,T3.province_code,t3.province_name,st_asgeojson(t3.geom) geomJson, " +
        " st_x(t2.geom) lon,st_y(t2.geom) lat " +
        " FROM biz_urban_road_mileage_info t1,biz_geographic_name t2,biz_city t3 " +
        " WHERE t1.parent_code = #{provinceCode} AND t1.city_code = t3.city_code " +
        " AND T1.city_name = t2.NAME AND st_contains(t3.geom, t2.geom) " +
        "</script>";

    @Select(GET_ROADMILEAGELIST_BY_PROVINCECODE)
    List<UrbanRoadMileageInfoVO> getRoadMileageList(@Param("provinceCode") String provinceCode);
}

3. 控制层 API

Controller 主要负责页面跳转与数据接口暴露，逻辑相对简单：

package com.yelang.project.extend.earthquake.controller;

import java.util.List;
import org.apache.shiro.authz.annotation.RequiresPermissions;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.ModelMap;
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.ResponseBody;
import com.yelang.framework.web.controller.BaseController;
import com.yelang.framework.web.domain.AjaxResult;
import com.yelang.project.extend.earthquake.domain.UrbanRoadMileageInfoVO;
import com.yelang.project.extend.earthquake.service.IUrbanRoadMileageInfoService;

@Controller
@RequestMapping("/eq/urbanroadmileageinfo")
public class UrbanRoadMileageInfoController extends BaseController {
    private String prefix = "earthquake/urbanroadmileageinfo";

    @Autowired
    private IUrbanRoadMileageInfoService urbanRoadMileageInfoService;

    @RequiresPermissions("eq:urbanroadmileageinfo:map")
    @GetMapping("/")
    public String main(ModelMap mmap) {
        return prefix + "/main";
    }

    @RequiresPermissions("eq:urbanroadmileageinfo:list")
    @GetMapping("/data/{pcode}")
    @ResponseBody
    public AjaxResult ewsnProvinceList(@PathVariable("pcode") String pcode) {
        List<UrbanRoadMileageInfoVO> dataList = urbanRoadMileageInfoService.getRoadMileageList(pcode);
        return AjaxResult.success().put("data", dataList);
    }
}

三、WebGIS 界面实现

前端使用 Leaflet 渲染地图，重点在于图例配置与 GeoJSON 数据的交互。

1. 里程图例及初始化

根据道路总长度设定颜色阈值，直观区分不同量级的路网规模。注意修正原逻辑中的颜色描述错误，确保 RGB 值与 Hex 码一致：

// 里程颜色配置
var colorList = [
    {name:"5千公里以下",color:"#00FF00",rgb:new Color(0, 255, 0),colorDesc:"绿色"},
    {name:"5千 -8 千公里",color:"#FFFF00",rgb:new Color(255, 255, 0),colorDesc:"黄色"},
    {name:"8 千 -1.1 万公里",color:"#FFA500",rgb:new Color(255, 165, 0),colorDesc:"橙色"},
    {name:"1.1 万 -1.4 万公里",color:"#113fc1",rgb:new Color(17, 63, 193),colorDesc:"蓝色"},
    {name:"1.4 万 -1.6 万公里",color:"#800080",rgb:new Color(128, 0, 128),colorDesc:"紫色"},
    {name:"1.6 万以上",color:"#FF0000",rgb:new Color(255, 0, 0),colorDesc:"红色"}
];

function getColorByLength(length){
    if(length >= 0 && length <= 5000) return "#00FF00";
    if(length >= 5001 && length <= 8000) return "#FFFF00";
    if(length >= 8001 && length <= 11000) return "#FFA500";
    if(length >= 11001 && length <= 14000) return "#113fc1";
    if(length >= 14001 && length <= 16000) return "#800080";
    if(length >= 16001) return "#FF0000";
}

2. 各地市信息展示

数据库中存储单位为米，前端展示需转换为万公里。通过 AJAX 获取数据后，解析 GeoJSON 并添加到地图图层：

function buildShowInfo(index, color, data){
    var length = parseFloat(data.totalLength) / (1000.0 * 10000);
    var result = "<div style='" + color + ";' animation-spaceInDown onclick='showDetails("+data.cityCode+")'><div>" + data.cityName;
    result += "<span>:" + length.toFixed(2) + "万公里</span></div></div>";
    return result;
}

function previewRoadMap(pid, provinceCode, name){
    previewProvince(pid, name);
    $.ajax({
        type: "get",
        url: ctx + "eq/urbanroadmileageinfo/data/" + provinceCode,
        dataType: "json",
        success: function(result){
            if(result.code == web_status.SUCCESS){
                collisionLayer.clearLayers();
                var dataArray = result.data;
                if(dataArray != null && dataArray.length > 1){
                    for(var i = 0; i < dataArray.length; i++){
                        var areaData = dataArray[i];
                        var tempTotalLength = parseFloat(areaData.totalLength) / 1000.0;
                        var color = getColorByLength(tempTotalLength);
                        
                        // 绘制区域面
                        var areaLayer = L.geoJSON(JSON.parse(areaData.geomJson),{
                            style: {color: color, fillColor: color, weight: 3, opacity: 0.65, fillOpacity: 0.65}
                        }).addTo(mymap);
                        
                        // 添加行政中心标记
                        var myIcon = L.divIcon({
                            iconSize: null,
                            className: '',
                            popupAnchor: [5, 5],
                            shadowAnchor: [5, 5],
                            html: buildShowInfo(i, color, areaData)
                        });
                        L.marker([areaData.lat, areaData.lon], { icon: myIcon }).addTo(collisionLayer);
                    }
                    collisionLayer.addTo(showLayerGroup);
                }
            }
        },
        error: function(){
            $.modal.alertWarning("获取空间信息失败");
        }
    });
}

点击标记可调用 showDetails(cityCode) 展开更详细的分级统计，此处预留了扩展入口。

四、成果展示

系统运行后，可直观查看湖南省各地市道路里程排名。按降序排列如下：

1. 长沙市 (430100): 约 1775 万公里
2. 衡阳市 (430400): 约 1443 万公里
3. 岳阳市 (430600): 约 1422 万公里
4. 益阳市 (430900): 约 1307 万公里
5. 常德市 (430700): 约 1193 万公里 ...

从空间分布来看，路网密集区主要集中在东部和东南部，如长沙、衡阳、岳阳等地。湘西北山区因地形限制，道路里程相对较少，这符合地理环境特征。南部地区除衡阳外，邵阳、永州等地仍有较大发展空间。

五、总结

本实践完成了一个功能完善的湖南省道路长度 WebGIS 系统。通过 Java 后端处理空间 SQL 查询，配合 Leaflet 前端进行动态渲染，实现了数据的高效管理与直观展示。未来可进一步集成实时路况监测或大数据预测模块，提升系统的智能化水平。