/// <summary>
        /// 方法说明:根据根节点加载子节点
        /// 作    者:jason.tang
        /// 完成时间:2013-03-06
        /// </summary>
        /// <param name="parentNode">父节点</param>
        private void LoadMaterialChildNode(TreeNode parentNode)
        {
            if (parentNode == null)
            {
                return;
            }

            parentNode.Nodes.Clear();

            //查找根节点(产品文件夹)下的子节点
            List <Model.MaterialRelationModule> relationModuleList =
                MaterialModuleBLL.GetMaterialVersionModuleListByVersionId(parentNode.Name);

            if (relationModuleList.Count <= 0)
            {
                return;
            }

            relationModuleList.ForEach((o) =>
            {
                TreeNode node = new TreeNode();
                node.Text     = o.name;
                node.Tag      = o.ChildVerId;
                node.Name     = o.ChildVerId;
                node.ImageKey = "materialG";

                List <Model.MaterialRelationModule> childRelationModuleList =
                    MaterialModuleBLL.GetMaterialVersionModuleListByVersionId(node.Name);
                if (childRelationModuleList.Count > 0)
                {
                    LoadPBomChildNode(node);
                }

                parentNode.Nodes.Add(node);
            });
        }