treeview展开一个节点就关闭其他节点

前台代码: 
<asp:TreeView ID="TreeView1" runat="server" ExpandDepth="0" OnTreeNodeExpanded="TreeView1_TreeNodeExpanded" ShowLines="True"> 
要害是:OnTreeNodeExpanded="TreeView1_TreeNodeExpanded" 

后台代码: 

  protected void TreeView1_TreeNodeExpanded(object sender, TreeNodeEventArgs e) 
        { 
            TreeNodeCollection ts = null; 
            if (e.Node.Parent == null) 
            { 
                ts = ((TreeView)sender).Nodes; 
            } 
            else 
                ts = e.Node.Parent.ChildNodes; 
            foreach (TreeNode node in ts) 
            { 
                if (node != e.Node) 
                { 
                    node.Collapse(); 
                } 
            } 
        } 
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