如何记住ASPxTreeView节点的展开状态

最新推荐文章于 2025-05-29 17:00:00 发布

原创最新推荐文章于 2025-05-29 17:00:00 发布 · 2.7k 阅读

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#string #session #callback #menu #server #服务器

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本文介绍如何在ASP.NET应用程序中使用ASPxTreeView组件记录并应用节点的展开状态，通过客户端事件和服务器端合并Session数据实现用户体验的连续性。

如果在MasterPage放一个ASPxTreeView来表示整个系统的作业树，从用户体验来说，在每个页面切换时记住这棵树的节点的展开状态比较好，如何记录呢？

在ASPxTreeView的客户端事件ExpandedChanged里面，借助ASPxCallback，把节点的展开/收拢信息传回服务器。

<Script>
 function doTreeExpandedChanged(s, e) {
    Callback_TreeState.PerformCallback(e.node.name + "|" + e.node.GetExpanded());
 }
 </Script>
 <dx:ASPxTreeView ID="Menu_TreeList" runat="server" 
   AllowSelectNode="True" ClientInstanceName="Menu_TreeList">
    <ClientSideEvents ExpandedChanged="function(s,e){doTreeExpandedChanged(s,e);}" />
 </dx:ASPxTreeView>
 <dx:ASPxCallback runat="server" ID="Callback_TreeState" 
   OnCallback="Callback_TreeStateCallback">
 </dx:ASPxCallback>

服务器收到节点的展开/收拢信息后，与Session中的信息合并：

（我这里的Node.Name是int类型的）。

    private const string SessionTreeStateName = "ProcessTreeState";
    protected override void OnLoad(EventArgs e)
    {
        base.OnLoad(e);
        string vPageName = Page.Request.RawUrl;
        if (!Page.IsPostBack)
        {
            BuildProcessTree();
        }
        if (!this.Callback_TreeState.IsCallback)
        {
            ApplyTreeState();
        }
    }
    private void ApplyTreeState()
    {
        string vTreeState = (string)Session[SessionTreeStateName];
        if (!string.IsNullOrEmpty(vTreeState))
        {
            string[] vArray = vTreeState.Split(',');
            foreach (TreeViewNode vNode in Menu_TreeList.Nodes)
            {
                ScanTreeNodeState(vNode, vArray);
            }
        }
        else
        {
            if (Menu_TreeList.Nodes.Count > 0)
            {
                Menu_TreeList.Nodes[0].Expanded = true;
                string[] vList = new string[int.Parse(Menu_TreeList.Nodes[0].Name) + 1];
                vList[vList.Length - 1] = true.ToString();
                Session[SessionTreeStateName] = string.Join(",", vList);
            }
        }
    }
    /// <summary>
    /// 合并节点展开状态到Session
    /// </summary>
    /// <param name="ANativeSate"></param>
    private void MergeTreeState(string ANativeSate)
    {
        string vState = (string)Session[SessionTreeStateName];
        if (!string.IsNullOrEmpty(vState))
        {
            if (!String.IsNullOrEmpty(ANativeSate))
            {
                string[] vArray = vState.Split(',');
                string[] vArray2 = ANativeSate.Split(',');
                List<string> vList = vArray.ToList();
                for (int i = 0; i < vArray2.Length; i++)
                {
                    for (int j = vList.Count - 1; j < i; j++)
                        vList.Add("");
                    if (!string.IsNullOrEmpty(vArray2[i]))
                        vList[i] = vArray2[i];
                }
                string vNewState=string.Join(",", vList.ToArray());
                Session[SessionTreeStateName] = vNewState;
            }
        }
        else
            Session[SessionTreeStateName] = ANativeSate;
    }
    private void ScanTreeNodeState(TreeViewNode ANode,string[] ATreeState)
    { 
        int vIndex = int.Parse(ANode.Name);
        if (vIndex < ATreeState.Length)
        {
            if (!String.IsNullOrEmpty(ATreeState[vIndex]))
            {
                ANode.Expanded = bool.Parse(ATreeState[vIndex]);
            }
        }
        foreach (TreeViewNode vNode in ANode.Nodes)
        {
            ScanTreeNodeState(vNode, ATreeState);
        }
    }
    protected void Callback_TreeStateCallback(object source, DevExpress.Web.ASPxCallback.CallbackEventArgs e)
    {
        ///把节点的展开状态合并到Session中
        string[] vParams = e.Parameter.Split('|');
        string[] vList=new string[int.Parse(vParams[0])+1];
        vList[vList.Length - 1] = vParams[1];
        MergeTreeState(string.Join(",",vList));
    }