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WMS服务与WFS服务的优势互补例子之一（点击查询）

作者：互联网

假设在GeoServer服务器上，我有一个需求，需加载经过样式文件渲染过的图层，在这个图层上实现点击查询，并将查询结果要素用几何图形进行渲染并放到图层上，可以怎么实现呢？

思路：
1.样式文件渲染
那就是在服务端进行渲染后再加载到页面，这个用WMS服务可以实现

2.点击查询
WMS也能够实现点击查询

WMS输出格式 可以知道输出的格式有限，在开发者工具上查看点击图层时发送的请求，可以发现request为getFeatureInfo，就是只能够获取图层的属性表信息，不能获取几何信息

换成getMap

这就有问题了，我们不能获取几何信息，那就不能创建几何图形了鸭

所以，我们可以考虑WFS，因为它有一个请求为getFeature，经过测试，可以知道getFeature不仅可以返回属性表信息，还可以返回图层要素的几何信息。
cql_filter介绍

// ArcGIS for JS的js代码
view.on("click", (event) => {
  let url = "http://localhost:9090/geoserver/guangdong/wfs";
  let query = {
    SERVICE: "WFS",
    REQUEST: "GetFeature",
    VERSION: "2.0.0",
    TYPENAMES: "guangdong",
    OUTPUTFORMAT: "json",
    SRSNAME: "EPSG:4326",
    cql_filter: `INTERSECTS(the_geom,%20POINT%20(${event.mapPoint.latitude}%20${event.mapPoint.longitude}))`,
  };
  //发送请求
  get(url, query, callRes);
});

因此，整体思路就是，用WMS加载渲染过后的图层（因为图层数据是在GeoServer，正常没有关闭WFS服务的话，也是能用的），用WFS服务的getFeature过滤点击查询的点，返回点击的图层要素的图层属性和几何属性，再用Graphic进行创建及渲染成几何图形，添加至图层。

所有代码

点击查看代码 
<html>
<head>
  <meta charset="utf-8" />
  <meta name="viewport" content="initial-scale=1,maximum-scale=1,user-scalable=no" />
  <title>demo</title>
  <style>
    html,
    body,
    #viewDiv {
      padding: 0;
      margin: 0;
      height: 100%;
      width: 100%;
    }
  </style>

  <link rel="stylesheet" href="https://js.arcgis.com/4.22/esri/themes/light/main.css" />
  <script src="https://js.arcgis.com/4.22/"></script>

  <script>
    require([
      "esri/Map",
      "esri/views/SceneView",
      "esri/layers/WMSLayer",
      "esri/layers/SceneLayer",
      "esri/layers/GraphicsLayer",
      "esri/layers/WFSLayer",
      "esri/Graphic",
    ], (
      Map,
      SceneView,
      WMSLayer,
      SceneLayer,
      GraphicsLayer,
      WFSLayer,
      Graphic,
    ) => {
      const map = new Map({
        basemap: "topo-vector",
      });

      const view = new SceneView({
        container: "viewDiv",
        map: map,
      });

      // 加载wmsLayer
      let wmsLayer = new WMSLayer({
        url: "http://localhost:9090/geoserver/guangdong/wms",
        sublayers: [
          {
            name: "guangdong",
          },
        ],
      });
      console.log("wmsLayer", wmsLayer);
      map.add(wmsLayer);

      view.when(() => {
        view.goTo(wmsLayer.fullExtent);
      });

      // 创建一个GraphicLayer,用来绘制查询结果
      var graphicsLayer = new GraphicsLayer();
      map.add(graphicsLayer);

      view.on("click", (event) => {
        let url = "http://localhost:9090/geoserver/guangdong/wfs";
        let query = {
          SERVICE: "WFS",
          REQUEST: "GetFeature",
          VERSION: "2.0.0",
          TYPENAMES: "guangdong",
          OUTPUTFORMAT: "json",
          SRSNAME: "EPSG:4326",
          cql_filter: `INTERSECTS(the_geom,%20POINT%20(${event.mapPoint.latitude}%20${event.mapPoint.longitude}))`,
        };
        //发送请求
        get(url, query, callRes);
      });

      //回调函数
      function callRes(result) {
        console.log("result:", result);
        addGraphics(result.features);
      }

      //发送请求
      function get(url, query, callback) {
        // 如果有参数，先把参数拼接在url后面
        if (query) {
          url += "?";
          for (let key in query) {
            url += `${key}=${query[key]}&`;
          }
          // 去除最后多余的那一个&
          url = url.slice(0, -1);
        }
        let xhr = new XMLHttpRequest();
        xhr.responseType = "json";
        xhr.open("get", url);
        xhr.send();
        xhr.onreadystatechange = function () {
          if (xhr.readyState === 4) {
            if (xhr.status === 200) {
              // console.log("xhr",xhr)
              callback(xhr.response);
            }
          }
        };
      }

      //添加几何图形
      function addGraphics(result) {
        graphicsLayer.removeAll();
        result.forEach(function (item) {
          if (item.geometry.type === "point") {
          } else if (item.geometry.type === "polyline") {
          } else if (
            item.geometry.type === "polygon" ||
            item.geometry.type === "MultiPolygon"
          ) {
            const fillSymbol = {
              type: "simple-fill",
              color: [227, 227, 2, 0.8],
              outline: {
                color: [255, 255, 255],
                width: 1,
              },
            };
            var polygons = item.geometry.coordinates.map(ring => {
              return new Graphic({
                geometry: {
                  type: "polygon",
                  rings: ring,
                },
                symbol: fillSymbol,
                spatialReference: view.spatialReference,
              });
            })
          }
          graphicsLayer.addMany(polygons);
          view.goTo(polygons);
        });
      }
    });
  </script>
</head>

<body>
  <div id="viewDiv"></div>
</body>
</html>

标签：服务,xhr,WMS,url,let,query,WFS,图层,view
来源： https://www.cnblogs.com/echohye/p/16534009.html