TreeView保存当前节点展开状态

 由于微软的TreeView设计成提交式的，所以有的人写程序的时候喜欢在把node.NavigateUrl写成本页再加上一个参数（我原来也喜欢这么做）,这样做的后果是一提交之后，treeView又回到原来的样式，原来点的节点又缩回去，让用户不知道点了哪一个节点，网上有很多人给了思路，以下是解决方法。

一：首先在给节点赋值的时候不要给NavigateUrl赋值。把整个TreeView的TreeView1.ExpandDepth设成1级或者二级，看你的情况而定，默认为全部展开。

二：给TreeView添加SelectedNodeChanged事件，如下：

     protected void TreeView1_SelectedNodeChanged(object sender, EventArgs e)
    {
        string typeId = TreeView1.SelectedNode.Value;
        string typeName = TreeView1.SelectedNode.Text;
        string path = "Default.aspx?typeId=" + typeId + "&typeName=" + Server.UrlEncode(typeName);
        Context.Items["path"] = TreeView1.SelectedNode.ValuePath;
        Server.Transfer(path);
    }

三：在Page_load事件加入以下代码：

     if (!IsPostBack)
     {

               if (Context.Items["path"] != null)
                {
                      TreeNode node = TreeView1.FindNode(Context.Items["path"].ToString()) as TreeNode;
                    if (node != null)
                    {
                        expand(node);
                        node.Selected = true;
                    }
                }
           
        }

四：另外写一个方法 expand(TreeNode node)

   private void expand(TreeNode node)
    {
        if (node.Parent != null)
        {
            node.Parent.Expanded = true;
            expand(node.Parent);
        }
    }

五：设置一下SelectNodeStyle，使选择的节点满足您的要求。

  

注意:

关于TreeView的OnSelectedNodeChanged事件

只有节点(Node)的SelectAction被设定为Select时才能够触发该事件，而TreeView的DataSource如果为siteMap则默认该属性值为None,并且如果节点(Node)的Target属性被设定为一个url则会忽略OnSelectedNodeChanged，而直接跳转到该url

因此使用siteMap作为TreeView的数据源时，添加OnTreeNodeDataBound事件的回调方法，将上诉2个属性进行变更

 

<asp:TreeView ID="tvAcc" runat="server" ShowLines="True" ExpandDepth="1" NodeIndent="0"
    LeafNodeStyle-Width="100%" NodeStyle-Width="100%" ParentNodeStyle-Width="100%"
    RootNodeStyle-Width="100%" SelectedNodeStyle-Width="100%" OnSelectedNodeChanged="tvAcc_SelectedNodeChanged">
    <Nodes>
        <asp:TreeNode Text="Test1" Value="Test1">
            <asp:TreeNode Text="Test11" Value="Test11">
                <asp:TreeNode Text="Test111" Value="Test111"></asp:TreeNode>
            </asp:TreeNode>
        </asp:TreeNode>
        <asp:TreeNode Text="Test2" Value="Test2">
            <asp:TreeNode Text="Test11" Value="Test11">
                <asp:TreeNode Text="Test111" Value="Test111"></asp:TreeNode>
            </asp:TreeNode>
            <asp:TreeNode Text="Test22" Value="Test22">
                <asp:TreeNode Text="Test221" Value="Test221"></asp:TreeNode>
                <asp:TreeNode Text="Test222" Value="Test222"></asp:TreeNode>
            </asp:TreeNode>
        </asp:TreeNode>
        <asp:TreeNode Text="Test3" Value="Test3">
            <asp:TreeNode Text="Test31" Value="Test31">
                <asp:TreeNode Text="Test311" Value="Test311"></asp:TreeNode>
            </asp:TreeNode>
        </asp:TreeNode>
        <asp:TreeNode Text="Test4" Value="Test4">
            <asp:TreeNode Text="Test41" Value="Test41"></asp:TreeNode>
        </asp:TreeNode>
    </Nodes>
</asp:TreeView>

后台代码：

protected void Page_Load(object sender, EventArgs e)
        {
            if (!IsPostBack)
            {
                if (Context.Items["path"] != null)
                {
                    TreeNode node = tvAcc.FindNode(Context.Items["path"].ToString()) as TreeNode;
                    if (node != null)
                    {
                        expand(node);
                        node.Selected = true;
                    }
                }
            }
        }

        private void expand(TreeNode node)
        {
            if (node.Parent != null)
            {
                node.Parent.Expanded = true;
                expand(node.Parent);
            }
        }


        protected void tvAcc_SelectedNodeChanged(object sender, EventArgs e)
        {
            string typeId = tvAcc.SelectedNode.Value;
            string typeName = tvAcc.SelectedNode.Text;
            string path = "Default.aspx?typeId=" + typeId + "&typeName=" + Server.UrlEncode(typeName);
            //在Node.Value中保存NavigationUrl信息，通过Server.Transfer跳转到指定页面。替换掉此处Sample用的Default.aspx
            Context.Items["path"] = tvAcc.SelectedNode.ValuePath;
            Server.Transfer(path);//Response.Redirect(path);
        }

Backup for 动态绑定TreeView后台Sample：

        private void BindDocNode()
        {
            TreeNode rootDoc = new TreeNode("Document Center", "Document Center", "", "#", "");
            rootDoc.Expanded = false;
            tvAcc.Nodes.Add(rootDoc);

            DocBLL docBLL = new DocBLL();
            DataTable dtDoc = new DataTable();
            dtDoc = docBLL.GetItems();

            for (int i = 0; i < dtDoc.Rows.Count; i++)
            {
                string itemID = dtDoc.Rows[i]["ID"].ToString();
                string itemTitle = dtDoc.Rows[i]["itemTitle"].ToString();
                TreeNode treeDoc = new TreeNode(itemTitle, "DocumentCenter.aspx?did=" + itemID, "", "", "");
                rootDoc.ChildNodes.Add(treeDoc);
            }
        }