Arcengine geometric network 流向代码（转载）

转自：http://www.thinkgis.cn/topic/54203518d97a20db38e59101/

以前学习几何网络时，对效用网络流向进行了总结，原理与效果图见：http://thinkgis.duapp.com/topic/542034b0d97a20db38e59100 但是代码一直没贴出来，因为网上有很多类似的代码，这几天一个网友想交流一下，自己也好久没看这个代码了，在这里把显示流向的代码贴出来分享下，如果你有更好的方法，可以的话也请你分享一下，谢谢。

/// <summary>
    /// 得到IGeometricNetwork
    /// </summary>
    /// <param name="layer"></param>
    /// <returns></returns>
    public static IGeometricNetwork GetGeometricNetwork(ILayer layer)
    {
        IFeatureClass featureClass = ((IFeatureLayer)layer).FeatureClass;
        IFeatureDataset featureDataset = featureClass.FeatureDataset;
        INetworkCollection networkCollection = featureDataset as INetworkCollection;
        IGeometricNetwork geometricNetwork = networkCollection.get_GeometricNetworkByName(GN_NAME);
        return geometricNetwork;
    }

    /// <summary>
    /// 显示网络流向
    /// </summary>
    /// <param name="map"></param>
    public static void ShowFlowDirection(IMap map)
    {
        IGeometricNetwork geometricNetwork = GetGeometricNetwork(map.get_Layer(0));

        IFeatureClass featureClass = ((IFeatureLayer)map.get_Layer(0)).FeatureClass;
        IFeatureDataset featureDataset = featureClass.FeatureDataset;
        IWorkspace workspace = featureDataset.Workspace;
        IWorkspaceEdit workspaceEdit = workspace as IWorkspaceEdit;
        workspaceEdit.StartEditing(false);
        workspaceEdit.StartEditOperation();


        ILayer netLayer = null;

        //得到网络图层
        for (int i = 0; i < map.LayerCount; i++)
        {
            if (map.get_Layer(i).Name == NET_NAME)
            {
                netLayer = map.get_Layer(i);
                break;
            }
        }

        if (netLayer != null)
        {
            IFeatureClass netFeatureClass = ((IFeatureLayer)netLayer).FeatureClass;
            IFeatureCursor featureCursor =