asp.net 2.0中TREEVIEW中动态增加结点

发布: 2007-6-30 18:56 | 作者: admin | 来源: | 查看: 31次 | 进入软件测试论坛讨论

     在asp.net 2.0中，要动态从数据库中取出内容，动态增加结点，其实不难，比如以SQL SERVER 2000的PUBS数据库为例子，要以树型列表方式，取出作者，做为根结点，然后取出每位作者写过什么书，作为子结点，可以这样

  <%@ Page Language="C#"%>
  <%@ Import Namespace="System.Data"%>
  <%@ Import Namespace="System.Data.SqlClient"%>
  <%@ Import Namespace="System.Configuration"%>

  <!DOCTYPE htmlPUBLIC"-//W3C//DTD XHTML 1.1//EN""http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">

  <html xmlns="http://www.w3.org/1999/xhtml">
  <head runat="server">
   <title>Dynamic Population of the TreeView Control</title>
   <script runat=server>
  void Node_Populate(object sender,
   System.Web.UI.WebControls.TreeNodeEventArgs e)
   {
   if(e.Node.ChildNodes.Count == 0)
   {
   switch( e.Node.Depth )
   {
   case 0:
   FillAuthors(e.Node);
   break;
   case 1:
   FillTitlesForAuthors(e.Node);
   break;
   }
   }
   }

   void FillAuthors(TreeNode node)
   {
   string connString = System.Configuration.ConfigurationSettings.
  ConnectionStrings["NorthwindConnnection"].ConnectionString;
   SqlConnection connection = new SqlConnection(connString);
   SqlCommand command = new SqlCommand("Select * From
   authors",connection);
   SqlDataAdapter adapter = new SqlDataAdapter(command);
   DataSet authors = new DataSet();
   adapter.Fill(authors);
   if (authors.Tables.Count > 0)
   {
   foreach (DataRow row in authors.Tables[0].Rows)
   {
   TreeNode newNode = new
   TreeNode(row["au_fname"].ToString() + " " +
   row["au_lname"].ToString(),
   row["au_id"].ToString());
   newNode.PopulateOnDemand = true;
   newNode.SelectAction = TreeNodeSelectAction.Expand;
   node.ChildNodes.Add(newNode);
   }
   }
   }

   void FillTitlesForAuthors(TreeNode node)
   {
   string authorID = node.Value;
   string connString = System.Configuration.ConfigurationSettings.
  ConnectionStrings["NorthwindConnnection"].ConnectionString;
   SqlConnection connection = new SqlConnection(connString);
   SqlCommand command = new SqlCommand("Select T.title,
  T.title_id From titles T" +
  " Inner Join titleauthor TA on
  T.title_id = TA.title_id " +
  " Where TA.au_id = " + authorID + " ", connection);
   SqlDataAdapter adapter = new SqlDataAdapter(command);
   DataSet titlesForAuthors = new DataSet();
   adapter.Fill(titlesForAuthors);
   if (titlesForAuthors.Tables.Count > 0)
   {
   foreach (DataRow row in titlesForAuthors.Tables[0].Rows)
   {
   TreeNode newNode = new TreeNode(
  row["title"].ToString(), row["title_id"].ToString());
   newNode.PopulateOnDemand = false;
   newNode.SelectAction = TreeNodeSelectAction.None;
   node.ChildNodes.Add(newNode);
   }
   }
   }

   </script>
  </head>
  <body>
   <form id="form1" runat="server">
   <div>
   <asp:TreeViewRunat="Server" ExpandImageUrl="Images/closed.gif"
   CollapseImageUrl="Images/open.gif"
   OnTreeNodePopulate="Node_Populate" ID="tvwauthors">
   <Nodes>
   <asp:TreeNodeText="Authors" PopulateOnDemand=true
  Value="0"/>
   </Nodes>
   </asp:TreeView>
   </div>
   </form>
  </body>
  </html>
   其中，注意ontreenodepopulate事件，是在展开树的结点时发生的，这里定义了自定义的NODE_POPULATE,在node_populate中，检查当前结点的深度，如果是0，就是根结点，于是就调用FillAuthors过程，取出所有的作者，如果深度是1，则是叶子结点，调用FillTitlesForAuthors过程。其中，要注意它们中的动态建立树结点的过程，如：
   TreeNode newNode = new TreeNode(row["au_fname"].ToString() + " " +
   row["au_lname"].ToString(),

   row["au_id"].ToString());

   newNode.PopulateOnDemand = true;

   newNode.SelectAction = TreeNodeSelectAction.Expand;

   node.ChildNodes.Add(newNode);
  其中， popluateondemand属性表明，该结点会动态扩展。