已被阅读 2861 次 | 文章分类:OpenLayers | 2021-06-30 21:12
空间查询是GIS的最基本和常用的功能;通过空间几何对象查询出对应范围内的数据
1 基本思路
(1) 首先利用鼠标交互或者自定义的坐标创建空间几何对象;
(2)拼接查询参数 利用new format.WFS().writeGetFeature方法拼接查询参数,其中的参数都来自于geoserver发布的wfs服务当中,可以在geoserver服务管理中查看,并填写
// 拼接查询参数
var featureRequest = new format.WFS().writeGetFeature({
srsName: 'EPSG:4326',
featureNS: 'http://localhost:8080', //命名空间
featurePrefix: 'sldDemo', //工作区域
featureTypes: ['province'], //图层名
outputFormat: 'application/json',
geometryName: "the_geom",
filter: new format.filter.Intersects('the_geom', geometry)
});
其中空间查询最重要的部分是 filter参数,这里调用的是相交查询命令:new format.filter.Intersects('the_geom', geometry)
(3) 执行post请求,得到查询结果
(4) 将查询的json数据生成要素,并添加到地图就可以显示了
// 从geojson数据生成feature
var features = new ol.format.GeoJSON().readFeatures(json);
source1.addFeatures(features);
2 全部代码
import * as ol from 'ol';
import * as layer from 'ol/layer';
import * as source from 'ol/source';
import * as style from 'ol/style';
import * as format from 'ol/format'
import 'ol/ol.css';
var map = new ol.Map({
target: 'map',
layers: [
new layer.Tile({
source: new ol.source.OSM()
}),
],
view: new ol.View({
center: [121.478815, 31.24161],
zoom: 10,
projection: 'EPSG:4326'
})
});
var source1 = new source.Vector({
wrapX: false
});
var vector1 = new layer.Vector({
source: source1,
style: new style.Style({
fill: new style.Fill({
color: 'rgba(37,241,239,0.2)'
}),
stroke: new style.Stroke({
color: '#264df6',
width: 2
})
})
});
map.addLayer(vector1);
var draw = new ol.interaction.Draw({
source: source,
type: 'Polygon',
/*用于交互绘制图形时所设置的样式*/
style: new ol.style.Style({
fill: new ol.style.Fill({
color: 'yellow'
}),
stroke: new ol.style.Stroke({
color: '#ffcc33',
width: 2
}),
image: new ol.style.Circle({
radius: 5,
stroke: new ol.style.Stroke({
color: 'red'
}),
fill: new ol.style.Fill({
color: 'rgba(255, 255, 255, 0.2)'
})
})
})
});
map.addInteraction(draw);
draw.on("drawend", function (evt) {
source.clear();
var feature = evt.feature;
var inputGeometry = feature.getGeometry();
specialQuery(inputGeometry);
});
function specialQuery(geometry) {
// 拼接查询参数
var featureRequest = new format.WFS().writeGetFeature({
srsName: 'EPSG:4326',
featureNS: 'http://localhost:8080', //命名空间
featurePrefix: 'sldDemo', //工作区域
featureTypes: ['province'], //图层名
outputFormat: 'application/json',
geometryName: "the_geom",
filter: new format.filter.Intersects('the_geom', geometry)
});
fetch('http://localhost:8080/geoserver/wfs', {
method: 'POST',
body: new XMLSerializer().serializeToString(featureRequest)
}).then(function (response) {
console.log(response.json());
return response.json();
}).then(function (json) {
// 从geojson数据生成feature
var features = new ol.format.GeoJSON().readFeatures(json);
source1.addFeatures(features);
map.getView().fit(source1.getExtent());
});
}
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