毫无疑问,Google Maps KmlLayer 是为了让你把数据发送给他们而设计的。
https://developers.google.com/maps/documentation/javascript/kml
请看以下日志。
var src = 'https://developers.google.com/maps/documentation/javascript/examples/kml/westcampus.kml';
var kmlLayer = new google.maps.KmlLayer(src, {
suppressInfoWindows: true,
preserveViewport: false,
map: your_gmap_object
});
创建标记、多边形,它们都是浏览器端解析和渲染。
从下一个网络日志中可以看出,KmlLayer类将源URL发送到Google服务器进行解析并(在其端执行某些操作),然后将解析结果发送回您的浏览器进行渲染。
//REQUEST from browser
https://maps.googleapis.com/maps/api/js/KmlOverlayService.GetOverlays?1shttps%3A%2F%2Fdevelopers.google.com%2Fmaps%2Fdocumentation%2Fjavascript%2Fexamples%2Fkml%2Fwestcampus.kml&callback=_xdc_._lidt3k&key=AIzaSyBeLTP20qMgxsQFz1mwLlzNuhrS5xD_a_U&token=103685
//RESPONSE from google server
/**/_xdc_._lidt3k && _xdc_._lidt3k( [0,"kml:cXOw0bjKUSmlnTN2l67v0Sai6WfXhSSWuyNaDD0mAzh6xfi2fYnBo78Y2Eg","|ks:;dc:tg;ts:51385071|kv:3|api:3",...
["KmlFile"],[[37.423017,-122.0927],[37.424194,-122.091498]],[["g74cf1503d602f2e5"],["g58e8cf8fd6da8d29"],["ge39d22e72437b02e"]],1,[["client","2"]],-21505,[["ks",";dc:tg;ts:51385071"],["kv","3"],["api","3"]]] )
如@capdragon所述,最好自己解析KML。
更新
这里是紧凑的KML解析器代码。仅适用于Google.maps标记和多边形。
HTML
<input type='file' accept=".kml,.kmz" onchange="fileChanged()">
脚本,我使用TypeScript,但它与JavaScript非常相似
file: any
fileChanged(e) {
this.file = e.target.files[0]
this.parseDocument(this.file)
}
parseDocument(file) {
let fileReader = new FileReader()
fileReader.onload = async (e: any) => {
let result = await this.extractGoogleCoords(e.target.result)
console.log(result)
}
fileReader.readAsText(file)
}
async extractGoogleCoords(plainText) {
let parser = new DOMParser()
let xmlDoc = parser.parseFromString(plainText, "text/xml")
let googlePolygons = []
let googleMarkers = []
if (xmlDoc.documentElement.nodeName == "kml") {
for (const item of xmlDoc.getElementsByTagName('Placemark') as any) {
let placeMarkName = item.getElementsByTagName('name')[0].childNodes[0].nodeValue.trim()
let polygons = item.getElementsByTagName('Polygon')
let markers = item.getElementsByTagName('Point')
for (const polygon of polygons) {
let coords = polygon.getElementsByTagName('coordinates')[0].childNodes[0].nodeValue.trim()
let points = coords.split(" ")
let googlePolygonsPaths = []
for (const point of points) {
let coord = point.split(",")
googlePolygonsPaths.push({ lat: +coord[1], lng: +coord[0] })
}
googlePolygons.push(googlePolygonsPaths)
}
for (const marker of markers) {
var coords = marker.getElementsByTagName('coordinates')[0].childNodes[0].nodeValue.trim()
let coord = coords.split(",")
googleMarkers.push({ lat: +coord[1], lng: +coord[0] })
}
}
} else {
throw "error while parsing"
}
return { markers: googleMarkers, polygons: googlePolygons }
}
输出
markers: Array(3)
0: {lat: 37.42390182131783, lng: -122.0914977709329}
...
polygons: Array(1)
0: Array(88)
0: {lat: -37.79825999283025, lng: 144.9165994157198}
...