获取当前Civil3D文档中的图层信息，并保存到文件

[CommandMethod("GetLayerNames")]
public void GetLayerNames()
{
    var list = new List<string>();
    using (var tr = db.TransactionManager.StartTransaction())
    {
        var lt = tr.GetObject(db.LayerTableId, OpenMode.ForRead) as LayerTable;
        foreach (var id in lt)
        {
            var ltr = tr.GetObject(id, OpenMode.ForRead) as LayerTableRecord;
            list.Add($"{ltr.Name},{ltr.Color},{ltr.Description}");
        }
        tr.Commit();
    }
    var sfd = new SaveFileDialog();
    sfd.InitialDirectory = @"C:\Users\Administrator\Desktop";
    sfd.Title = "请选择要保存的位置：";
    sfd.Filter = "TXT文件|*.txt|所有文件|*.*";
    sfd.ShowDialog();
    var path = sfd.FileName;
    if (path == "") return;
    using (var fsWrite = new FileStream(path, FileMode.Create, FileAccess.ReadWrite))
    {
        var sw = new StreamWriter(fsWrite);
        foreach (var s in list) sw.WriteLine(s);
    }
    MessageBox.Show("保存成功！");
}