在openlayer中当数据量比较大时可以放在一个layer上面-优快云博客

在实际情况中当遇见大量数据时openlyer加载会特别慢可以使用单图层批量加载 + 样式缓存 + 简化（在低缩放级别）

 		 drawList: [],
      tailwaterLayer: null,
      tailwaterStyleCache: {},

drawTailwaterArea(data) {
      const that = this;
      if (!Array.isArray(data) || data.length === 0) {
        if (that.tailwaterLayer && that.tailwaterLayer.getSource) {
          that.tailwaterLayer.getSource().clear(true);
        }
        that.drawList = [];
        return;
      }
      if (!that.tailwaterLayer) {
        that.tailwaterStyleCache = {};
        that.tailwaterLayer = new VectorLayer({
          source: new VectorSource(),
          zIndex: 9999,
          visible: true,
          updateWhileAnimating: false,
          updateWhileInteracting: false,
          declutter: true,
          // 样式函数：基于要素属性返回缓存的样式对象
          style: function(feature, resolution) {
            const params = feature.get("params") || {};
            const key = `${params.pondType}_${params.farmType}`;
            if (!that.tailwaterStyleCache[key]) {
              const c = {
            		color1: "rgba(85, 147, 255, 1)",
            		color2: "rgba(85, 147, 255, 0.7)"
          			}
              that.tailwaterStyleCache[key] = new Style({
                stroke: new Stroke({
                  color: c.color1,
                  width: 2
                }),
                fill: new Fill({
                  color: c.color2
                })
              });
            }
            return that.tailwaterStyleCache[key];
          }
        });
        if (that.map && that.map.addLayer) {
          that.map.addLayer(that.tailwaterLayer);
        }
      } else {
        // 复用已有图层：先清空要素
        that.tailwaterLayer.getSource().clear(true);
        // 如果该图层之前被移除（例如外部通过 map.removeLayer），确保重新添加到地图
        try {
          const layers =
            that.map && that.map.getLayers && that.map.getLayers().getArray();
          if (
            that.map &&
            Array.isArray(layers) &&
            layers.indexOf(that.tailwaterLayer) === -1
          ) {
            that.map.addLayer(that.tailwaterLayer);
          }
        } catch (e) {
          if (that.map && that.map.addLayer) {
            that.map.addLayer(that.tailwaterLayer);
          }
        }
      }

      // 记录单图层到 drawList（保持外部代码兼容性）
      that.drawList = [that.tailwaterLayer];

      const format = new GeoJSON();
      const features = [];
      const currentZoom =
        that.map && that.map.getView ? that.map.getView().getZoom() : null;

      data.forEach(item => {
        if (!item || !item.pondGeomJson) return;
        try {
          const feature = format.readFeature(item.pondGeomJson);
          feature.set("params", { ...item });

          // 可选：在较小缩放级别上进行几何简化以减少顶点
          if (currentZoom !== null && currentZoom < 12) {
            try {
              const geom = feature.getGeometry();
              if (geom && typeof geom.simplify === "function") {
                // tolerance 可根据需要调整
                const tolerance = 0.00005 * Math.pow(2, 12 - currentZoom);
                const simplified = geom.simplify(tolerance, true);
                feature.setGeometry(simplified);
              }
            } catch (e) {
            }
          }

          features.push(feature);
        } catch (e) {
        }
      });

      // 批量加入要素（比逐个 addFeature 更高效）
      if (features.length) {
        that.tailwaterLayer.getSource().addFeatures(features);
      }
    },