Multi Layer

<!--
  示例：多图层叠加
  要点：底图 + 矢量面 + 矢量点三层共存，图层顺序与可见性控制
  依赖：OpenLayers 10.3.1 · jsDelivr CDN
-->
<!DOCTYPE html>
<html lang="zh-CN">
<head>
<meta name="robots" content="noindex,follow">
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>多图层叠加</title>
<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/ol@10.3.1/ol.css">
<style>
  html,body{height:100%;margin:0}
  body{display:flex;flex-direction:column;overflow:hidden;
       font:13px/1.6 -apple-system,"Segoe UI","PingFang SC",sans-serif}
  .bar{flex:0 0 auto;padding:8px 12px;background:#f6f7f9;border-bottom:1px solid #e3e6ea;
       display:flex;gap:12px;align-items:center;font-size:12px;color:#58606e;flex-wrap:wrap}
  .bar label{display:flex;gap:5px;align-items:center;cursor:pointer}
  #map{flex:1 1 auto;min-height:0;background:#eef0f3}
</style>
</head>
<body>
<div class="bar">
  <label><input type="checkbox" id="tglArea" checked> 区域面</label>
  <label><input type="checkbox" id="tglCity" checked> 城市点</label>
  <span>图层总数：<b id="count">3</b></span>
</div>
<div id="map"></div>
<script src="https://cdn.jsdelivr.net/npm/ol@10.3.1/dist/ol.js"></script>
<script>
(function () {
  'use strict';

  if (typeof ol === 'undefined') {
    document.getElementById('map').innerHTML =
      '<div style="padding:20px;color:#b42318">OpenLayers 加载失败，请检查能否访问 cdn.jsdelivr.net</div>';
    return;
  }

  var fromLonLat = ol.proj.fromLonLat;

  /* 视图可拖动范围要传 [minX, minY, maxX, maxY]，整体做一次投影转换 */
  var extent = ol.proj.transformExtent(
    [115.50, 39.30, 117.30, 40.60],
    'EPSG:4326',
    'EPSG:3857'
  );

  /* 第一层：底图 */
  var baseLayer = new ol.layer.Tile({
    source: new ol.source.XYZ({url: 'https://server.arcgisonline.com/ArcGIS/rest/services/World_Street_Map/MapServer/tile/{z}/{y}/{x}', attributions: 'Tiles © Esri'})
  });

  /* 第二层：区域面，半透明填充，压在底图之上 */
  var areaLayer = new ol.layer.Vector({
    source: new ol.source.Vector({
      features: [new ol.Feature({
        geometry: new ol.geom.Polygon([[
          fromLonLat([116.20, 40.02]),
          fromLonLat([116.60, 40.02]),
          fromLonLat([116.60, 39.80]),
          fromLonLat([116.20, 39.80]),
          fromLonLat([116.20, 40.02])
        ]])
      })]
    }),
    style: new ol.style.Style({
      fill: new ol.style.Fill({ color: 'rgba(31,95,208,0.16)' }),
      stroke: new ol.style.Stroke({ color: '#1f5fd0', width: 2, lineDash: [6, 4] })
    })
  });

  /* 第三层：城市点，最上层，带文字标注 */
  var cities = [
    [116.391263, 39.907359, '天安门'],
    [116.273000, 39.999000, '颐和园'],
    [116.603000, 40.077000, '首都机场'],
    [116.413000, 39.509000, '大兴机场']
  ];

  var cityFeatures = cities.map(function (c) {
    var f = new ol.Feature({
      geometry: new ol.geom.Point(fromLonLat([c[0], c[1]])),
      name: c[2]
    });
    f.setStyle(new ol.style.Style({
      image: new ol.style.Circle({
        radius: 5,
        fill: new ol.style.Fill({ color: '#d0453a' }),
        stroke: new ol.style.Stroke({ color: '#ffffff', width: 2 })
      }),
      text: new ol.style.Text({
        text: c[2],
        offsetY: -14,
        font: '500 12px sans-serif',
        fill: new ol.style.Fill({ color: '#16181d' }),
        stroke: new ol.style.Stroke({ color: '#ffffff', width: 3 })
      })
    }));
    return f;
  });

  var cityLayer = new ol.layer.Vector({
    source: new ol.source.Vector({ features: cityFeatures }),
    zIndex: 10
  });

  var map = new ol.Map({
    target: 'map',
    layers: [baseLayer, areaLayer, cityLayer],
    view: new ol.View({
      center: fromLonLat([116.391263, 39.907359]),
      zoom: 10,
      extent: extent
    })
  });

  document.getElementById('tglArea').addEventListener('change', function () {
    areaLayer.setVisible(this.checked);
  });

  document.getElementById('tglCity').addEventListener('change', function () {
    cityLayer.setVisible(this.checked);
  });

  document.getElementById('count').textContent = map.getLayers().getLength();
})();
</script>
</body>
</html>