有没有办法将 OpenLayers 功能保存到另一个文件？

如何解决有没有办法将 OpenLayers 功能保存到另一个文件？

我使用了两张地图，一张是有人可以添加或删除功能的地方（管理文件），另一张是最终用户可以看到的（用户文件）。但是，在浏览器中刷新时，我无法保存在管理文件中添加的功能。

我想知道是否有办法保存特征并再次提取它们（对于两个文件）？

//the main map of the app
  var map = new ol.Map({
    target: 'map',layers: [
      new ol.layer.Tile({
        source: new ol.source.OSM()
      })
    ],view: new ol.View({
      center: ol.proj.fromLonLat([-90.055,35.147]),zoom: 17,})
  });
//---------------------------------------------------------
//---------------------------------------------------------
///this creates the markers for the map

  var iconFeature = new ol.Feature({
    geometry: new ol.geom.Point(ol.proj.fromLonLat([-90.055,35.147])),name: 'Somewhere else'
  });


  iconStyle = new ol.style.Style({
    image: new ol.style.Icon({
      anchor: [0.5,46],anchorXUnits: 'fraction',anchorYUnits: 'pixels',src: 'icon.png',})
  });

  //Sets specific style for that one point
  iconFeature.setStyle(new ol.style.Style({
    image: new ol.style.Icon({
      anchor: [0.5,})
  }));

  eventFeature.setStyle(new ol.style.Style({
    image: new ol.style.Icon({
      anchor: [0.5,})
  }));

  var eventLayerSource = new ol.source.Vector({
    features: [iconFeature]
  });

//individual layers for the user to switch through based on selection
  var event_Layer = new ol.layer.Vector({
    source: eventLayerSource,// style for all elements on a layer
    style: new ol.style.Style({
      image: new ol.style.Icon({
        anchor: [0.5,src: 'icon.png'
      })
    }),visible: true,tab_name: 'event'
  });

// display popup on click
  map.on('click',function (evt) {
    var coordinate = evt.coordinate;
    console.log(evt.coordinate);
    console.log(ol.proj.transform(evt.coordinate,'EPSG:3857','EPSG:4326'));
  });

  map.on('singleclick',function (evt) {
    var lonLat = ol.proj.transform(evt.coordinate,'EPSG:4326');
    var clickFeature = new ol.Feature({
      geometry: new ol.geom.Point(ol.proj.fromLonLat(lonLat)),name: window.prompt("Enter name of event","Event name"),});
    clickFeature.setStyle(iconStyle);
    clickFeature.setId(clickFeature.get('name'));
    eventLayerSource.addFeature(clickFeature);
  });
  map.on('dblclick',function(evt){
    eventLayerSource.removeFeature(
      eventLayerSource.getFeatureById(prompt("Enter name")));
  })

这是我的管理文件代码。由于我是 Openlayers 的新手，我很感激任何见解。

解决方法

您可以通过以 GeoJSON 或 KML 等格式编写已绘制的要素，然后将它们作为文本文件下载到计算机来保存已绘制的要素（只需在 HTML 中添加按钮即可保存/下载）

  function download(data,filename) {
    var blob = new Blob([data],{type: 'text/plain'});
    if (navigator.msSaveBlob) {
      navigator.msSaveBlob(blob,filename);
    } else {
      var link = document.createElement('a');
      link.href = URL.createObjectURL(blob);
      link.download = filename;
      link.click();
    }
  }

  document.getElementById('download-geojson').addEventListener('click',function () {
    var text = new ol.format.GeoJSON().writeFeatures(
      source.getFeatures(),{
        featureProjection: 'EPSG:3857',dataProjection: 'EPSG:4326'
      }
    );
    download(text,'features.json');
  });

  document.getElementById('download-kml').addEventListener('click',function () {
    var text = new ol.format.KML().writeFeatures(
      source.getFeatures(),'features.kml');
  });

文件中的数据可以像https://openlayers.org/en/latest/examples/drag-and-drop.html一样使用拖放功能再次显示