WMS Params

<!--
  示例：WMS 参数配置
  要点：TileWMS 的 params 与 updateParams，透明度与显隐独立控制
  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>WMS 参数配置</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}
  .bar label{display:flex;gap:5px;align-items:center;cursor:pointer}
  input[type=range]{width:100px}
  #map{flex:1 1 auto;min-height:0;background:#eef0f3}
</style>
</head>
<body>
<div class="bar">
  <label><input type="checkbox" id="visible" checked> 显示 WMS 图层</label>
  <label>透明度 <input type="range" id="opacity" min="0" max="1" step="0.1" value="0.7"></label>
  <label><input type="checkbox" id="tiled"> 使用 TILED 请求</label>
  <span id="info">—</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;
  }

  /* 公开演示服务，图层为美国各州边界 */
  var wmsSource = new ol.source.TileWMS({
    url: 'https://ahocevar.com/geoserver/wms',
    params: {
      LAYERS: 'topp:states',
      TILED: true,
      VERSION: '1.1.1',
      TRANSPARENT: true
    },
    serverType: 'geoserver',
    crossOrigin: 'anonymous'
  });

  var wmsLayer = new ol.layer.Tile({
    source: wmsSource,
    opacity: 0.7
  });

  new ol.Map({
    target: 'map',
    layers: [
      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'}) }),
      wmsLayer
    ],
    view: new ol.View({
      center: ol.proj.fromLonLat([-98.5, 39.5]),
      zoom: 4
    }),
    controls: ol.control.defaults.defaults({ attribution: false })
  });

  var info = document.getElementById('info');
  info.textContent = 'WMS 参数：' + wmsLayer.getSource().getParams().LAYERS;

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

  document.getElementById('opacity').addEventListener('input', function () {
    wmsLayer.setOpacity(Number(this.value));
  });

  /* 参数改变后必须 updateParams 才会重新发请求 */
  document.getElementById('tiled').addEventListener('change', function () {
    wmsSource.updateParams({ TILED: this.checked });
    info.textContent = 'TILED = ' + this.checked + '，已刷新请求';
  });
})();
</script>
</body>
</html>