PostGis+GeoServer+OpenLayers最短路径分析

使用PostGis存储路线数据，在GeoServer中发布路网图层和最短路径图层，通过OpenLayers建立路网和展示图层。

1、PostGis：PostgreSQL 12.4,
2、GeoServer：geoserver-2.17.2
3、OpenLayers：6.4.3

一、做成路网数据

1、在PostGis建立路网数据表，主键使用sequence，路网geom 使用geometry(LineString,4326)

CREATE SEQUENCE public.my_roads_id_seq
    INCREMENT 1
    START 1
    MINVALUE 1
    MAXVALUE 2147483647
    CACHE 1;
    
ALTER SEQUENCE public.my_roads_id_seq OWNER TO postgres;

CREATE TABLE public.my_roads
(
    id integer NOT NULL DEFAULT nextval('my_roads_id_seq'::regclass),
    name character varying(32) COLLATE pg_catalog."default",
    geom geometry(LineString,4326),
    CONSTRAINT my_roads_pkey PRIMARY KEY (id)
)TABLESPACE pg_default;

ALTER TABLE public.my_roads OWNER to postgres;

2、在GeoServer中发布路网图层

建立工作区，建立postgis的数据存储，发布my_roads图层。

EPSG使用4326，边框及经纬度为：【-180，-90 】【180，90】即可。

3、OpenLayers中建立路网

使用vue开发路网编辑画面。

实现方式，请参考：OpenLayers 在Vue中增删改

注意点：新增的线不再是newFeature.setGeometry(new MultiLineString([geometry.getCoordinates()]))

// 转换坐标
 let geometry = this.drewFeature.getGeometry().clone();
 geometry.applyTransform(function (flatCoordinates, flatCoordinates2, stride) {
   
   
     for (let j = 0; j < flatCoordinates.length; j += stride) {
   
   
         let y = flatCoordinates[j];
         let x = flatCoordinates[j + 1];
         flatCoordinates[j] = x;
         flatCoordinates[j + 1] = y;
     }
 });

 // 设置feature对应的属性，这些属性是根据数据源的字段来设置的
 let newFeature = new Feature();
 newFeature.setId('nyc_roads.new.' + this.newId);
 newFeature.setGeometryName('the_geom');
 newFeature.set('the_geom', null);
 newFeature.set('name', newFeature.getId());
 newFeature.setGeometry(new MultiLineString([geometry.getCoordinates()]));

而是newFeature.setGeometry(geometry);

// 转换坐标
let geometry = this.drewFeature.