本文基于腾讯课堂老胡的课《跟我学Openlayers--基础实例详解》做的学习笔记，使用的openlayers 5.3.x api。
源码 见 1044.html ，对应的 官网示例 https://openlayers.org/en/latest/examples/geojson.html?q=geojson
image.png
image.png
<!DOCTYPE html>
<html>
<head>
<title>geojson</title>
<link rel="stylesheet" href="../include/ol.css" type="text/css" />
<script src="../include/ol.js"></script>
</head>
<body>
<div id="map" class="map"></div>
<script>
var image = new ol.style.Circle({
radius: 5,
fill: null,
stroke: new ol.style.Stroke({ color: 'red', width: 1 })
});
//用颜色来区分各种geometry：点和多点是红色；直线和多线是绿色，多个多边形集合是黄色；单个多边形是蓝色
//geometry集合的颜色是洋红色。
var styles = {
'Point': new ol.style.Style({
image: image
}),
'LineString': new ol.style.Style({
stroke: new ol.style.Stroke({
color: 'green',
width: 1
})
}),
'MultiLineString': new ol.style.Style({
stroke: new ol.style.Stroke({
color: 'green',
width: 1
})
}),
'MultiPoint': new ol.style.Style({
image: image
}),
'MultiPolygon': new ol.style.Style({
stroke: new ol.style.Stroke({
color: 'yellow',
width: 1
}),
fill: new ol.style.Fill({
color: 'rgba(255, 255, 0, 0.1)'
})
}),
'Polygon': new ol.style.Style({
stroke: new ol.style.Stroke({
color: 'blue',
lineDash: [4],
width: 3
}),
fill: new ol.style.Fill({
color: 'rgba(0, 0, 255, 0.1)'
})
}),
'GeometryCollection': new ol.style.Style({
stroke: new ol.style.Stroke({
color: 'magenta',
width: 2
}),
fill: new ol.style.Fill({
color: 'magenta'
}),
image: new ol.style.Circle({
radius: 10,
fill: null,
stroke: new ol.style.Stroke({
color: 'magenta'
})
})
}),
'Circle': new ol.style.Style({
stroke: new ol.style.Stroke({
color: 'red',
width: 2
}),
fill: new ol.style.Fill({
color: 'rgba(255,0,0,0.2)'
})
})
};
var styleFunction = function (feature) {
return styles[feature.getGeometry().getType()];
};
var geojsonObject = {
'type': 'FeatureCollection',
'crs': {
'type': 'name',
'properties': {
'name': 'EPSG:3857'
}
},
'features': [{
'type': 'Feature',
'geometry': {
'type': 'Point',
'coordinates': [0, 0]
}
}, {
'type': 'Feature',
'geometry': {
'type': 'LineString',
'coordinates': [[4e6, -2e6], [8e6, 2e6]]
}
}, {
'type': 'Feature',
'geometry': {
'type': 'LineString',
'coordinates': [[4e6, 2e6], [8e6, -2e6]]
}
}, {
'type': 'Feature',
'geometry': {
'type': 'Polygon',
'coordinates': [[[-5e6, -1e6], [-4e6, 1e6], [-3e6, -1e6]]]
}
}, {
'type': 'Feature',
'geometry': {
'type': 'MultiLineString',
'coordinates': [
[[-1e6, -7.5e5], [-1e6, 7.5e5]],
[[1e6, -7.5e5], [1e6, 7.5e5]],
[[-7.5e5, -1e6], [7.5e5, -1e6]],
[[-7.5e5, 1e6], [7.5e5, 1e6]]
]
}
}, {
'type': 'Feature',
'geometry': {
'type': 'MultiPolygon',
'coordinates': [
[[[-5e6, 6e6], [-5e6, 8e6], [-3e6, 8e6], [-3e6, 6e6]]],
[[[-2e6, 6e6], [-2e6, 8e6], [0, 8e6], [0, 6e6]]],
[[[1e6, 6e6], [1e6, 8e6], [3e6, 8e6], [3e6, 6e6]]]
]
}
}, {
'type': 'Feature',
'geometry': {
'type': 'GeometryCollection',
'geometries': [{
'type': 'LineString',
'coordinates': [[-5e6, -5e6], [0, -5e6]]
}, {
'type': 'Point',
'coordinates': [4e6, -5e6]
}, {
'type': 'Polygon',
'coordinates': [[[1e6, -6e6], [2e6, -4e6], [3e6, -6e6]]]
}]
}
}]
};
var vectorSource = new ol.source.Vector({
features: (new ol.format.GeoJSON()).readFeatures(geojsonObject)
});
//标准的geojson中是没有圆形几何类型的，所以需要用OL的API特殊处理
vectorSource.addFeature(new ol.Feature(new ol.geom.Circle([5e6, 7e6], 1e6)));
var vectorLayer = new ol.layer.Vector({
source: vectorSource,
style: styleFunction
});
var map = new ol.Map({
layers: [
new ol.layer.Tile({
source: new ol.source.OSM()
}),
vectorLayer
],
target: 'map',
view: new ol.View({
center: [0, 0],
zoom: 2
})
});
console.log(vectorSource.getFeatures())
</script>
</body>
</html>
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