#### # new FeatureLayer()

要素图层(Leaflet)

##### 示例

混合开发模式

    // ES5引入方式
    const { IGSTileLayer, IGSFeatureLayer } = zondy.Layer
    const { SimpleFillSymbol } = zondy.Symbol
    const { initializeCRS, initializeOptions, FeatureLayerUtil } = zondy.leaflet
    // ES6引入方式
    import { IGSTileLayer, IGSFeatureLayer, SimpleFillSymbol } from "@mapgis/webclient-common"
    import "@mapgis/webclient-leaflet-plugin"
    const { initializeCRS, initializeOptions, FeatureLayerUtil } = zondy.leaflet

    // 构造一个瓦片图层对象作为底图
    const layer = new IGSTileLayer({
      // 服务基地址
      url: "http://{ip}:{port}/arcgis/rest/services/{服务名}/TileServer"
    });
    // 加载瓦片图层元数据
    layer.load().then(function () {
      // 通过瓦片图层元数据构造地图视图的初始化参数
      const crs = initializeCRS(layer)
      const mapViewOptions = {
        // 地图视图参考系
        crs: crs,
        // 初始化中心点
        center: [31.147781205532336,112.21905099757561],
        // 初始化级数
        zoom: 6
      }
      // 构造Leaflet地图视图对象
      const map = L.map('地图视图容器ID', mapViewOptions)
      // 构造瓦片图层的初始化参数
      const layerOptions = initializeOptions(layer)
      // 添加瓦片图层到地图视图中
      new zondy.leaflet.IGSTileLayer(layer.url, layerOptions).addTo(map)
      // 构造要素图层
      const featureLayer = new IGSFeatureLayer({
        // 服务基地址
        url: 'http://{ip}:{port}/igs/rest/services/{服务名}/FeatureServer'
      })
      // 查询要素
      featureLayer.queryFeatures({
        // 指定要查询的子图层
        layerId: '0',
        // 指定返回数据的坐标系
        outSrs: 'EPSG:4326',
        // 指定查询数量
        resultRecordCount: 100000
      }).then((result) => {
        // 创建Leaflet的要素图层
        const featureLayerLeaflet = new zondy.leaflet.FeatureLayer()
        // 添加要素图层
        featureLayerLeaflet.addTo(map)
        // 获取查询到的要素集合
        const features = result.features
        // 循环遍历要素，将要素转为Leaflet的几何对象并绘制
        features.forEach((feature) => {
          // 设置要素符号
          feature.symbol = new SimpleFillSymbol({
            color: 'rgba(244, 122, 31, 0.5)'
          })
          // 将要素转为Leaflet几何对象
          const graphic = FeatureLayerUtil.convertFeature(feature)
          // 添加并绘制要素
          featureLayerLeaflet.addLayer(graphic)
        })
      })
    })