openlayer4中使用geojson数据
<html>
<head>
<title>GeoJSONtitle>
<link rel="stylesheet" href="https://openlayers.org/en/v4.5.0/css/ol.css" type="text/css">
<script src="https://cdn.polyfill.io/v2/polyfill.min.js?features=requestAnimationFrame,Element.prototype.classList,URL">script>
<script src="https://openlayers.org/en/v4.5.0/build/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})
});
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, 0.5)'
})
}),
'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 = //geojson数据
var vectorSource = new ol.source.Vector({
features: (new ol.format.GeoJSON({featureProjection: 'EPSG:3857'})).readFeatures(geojsonObject),
//将EPSG:4326坐标系修改为EPSG:3857（根据数据格式来）
});
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',
controls: ol.control.defaults({
attributionOptions: /** @type {olx.control.AttributionOptions} */ ({
collapsible: false
})
}),
view: new ol.View({
center: ol.proj.transform([117.2736, 31.8646], 'EPSG:4326', 'EPSG:3857'),
//地图中心为117.2736, 31.8646，并把坐标投影转换为3857（web 墨卡托投影）
zoom: 5 // 并且定义地图显示层级为5
})
});
script>
body>
html>注意：ol.format.GeoJSON默认参考坐标系为 EPSG:4326.，根据实际需要进行更改。
