工作需要做一个网站的导航.需要树结构的导航.
导航数中的节点是从数据库中读取(表相关联),并且数中的叶子节点是按照筛选的类型来显示.
如何实现动态的生成树节点,并且能按类型进行筛选叶子节点?
查看TreeView的属性，会发现其中有一项是"PopulatNodesFromClient",意思为:是否尝试从客户端填充节点.
那么看到了解释之后,当然是选择值为:"True".
在给"PopulatNodesFromClient"赋值为"True"之后,在TreeView的属性事件中就有一项为TreeNodePopulate事件,为:正在填充TreeNode时激发某事件,那么在给该事件写方法时,就可以写从数据库中读取相应的子节点内容了.
所以,每当TreeNode增加一个节点时,便激发该事件,以填充其子节点.
在本例子中，只显示2层树结构,
protected void TreeView1_TreeNodePopulate(object sender, TreeNodeEventArgs e)
{
if (e.Node.ChildNodes.Count == 0)
{
switch (e.Node.Depth)
{
case 0:
PopulateCategories(e.Node);
break;
case 1:
PopulateProducts(e.Node);
break;
}
}
}
并且,该树还可以进行复选框选择,TreeView中有一项属性为ShowCheckBoxes,选择值为Leaf,这样每个叶子节点就会显示一个复选框.
获取TreeView选择框中被选中的节点代码如下:
foreach (TreeNode node in TreeView1.CheckedNodes)
{
arraystr.Add(node);
}
该列子的整个代码如下:
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default3.aspx.cs" Inherits="_Default" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>无标题页</title>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:Label ID="labelStatus" runat="server" Font-Size="12pt" Text="测试测试。" Width="87px"></asp:Label>
<br />
<asp:DropDownList ID="DropDownList1" runat="server"
Width="119px" OnSelectedIndexChanged="Button1_Click" AutoPostBack="True" AppendDataBoundItems="True">
</asp:DropDownList>
<asp:Button ID="Button1" runat="server" Text="提交筛选" OnClick="Button1_Click" /><br />
<asp:Button ID="submitbtn" runat="server" OnClick="submitbtn_Click" Text="提交选择" />
<asp:Button ID="Button2" runat="server" OnClick="Button2_Click" Text="清空选择" /><br />
<asp:Label ID="Label1" runat="server" Text="Label" Width="368px"></asp:Label><br />
<asp:TreeView ID="TreeView1" runat="server" Font-Size="12pt" MaxDataBindDepth="2"
OnTreeNodePopulate="TreeView1_TreeNodePopulate" Width="371px" ShowCheckBoxes="Leaf">
<Nodes>
<asp:TreeNode PopulateOnDemand="True" Text="产品列表" Value="产品列表"></asp:TreeNode>
</Nodes>
</asp:TreeView>
</div>
</form>
</body>
</html>
using System;
using System.Data;
using System.Collections;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Data.SqlClient;
public partial class _Default : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
SqlCommand sqlQuery = new SqlCommand(
"Select CategoryName, CategoryID From Categories");
DataSet resultSet;
resultSet = RunQuery(sqlQuery);
DropDownList1.DataSource = resultSet.Tables[0].DefaultView;
DropDownList1.DataTextField = "CategoryName";
DropDownList1.DataValueField = "CategoryID";
DropDownList1.DataBind();
}
protected void TreeView1_TreeNodePopulate(object sender, TreeNodeEventArgs e)
{
if (e.Node.ChildNodes.Count == 0)
{
switch (e.Node.Depth)
{
case 0:
PopulateCategories(e.Node);
break;
case 1:
PopulateProducts(e.Node);
break;
}
}
}
void PopulateCategories(TreeNode node)
{
SqlCommand sqlQuery = new SqlCommand();
if ((Session["typeorder"] == null) || (Session["typeorder"].ToString() == "All"))
{
sqlQuery.CommandText = "Select CategoryName, CategoryID From Categories";
}
else
{
sqlQuery.CommandText = "Select CategoryName, CategoryID From Categories where CategoryID ='" + Session["typeorder"].ToString()+"'";
}
DataSet resultSet;
resultSet = RunQuery(sqlQuery);
if (resultSet.Tables.Count > 0)
{
foreach (DataRow row in resultSet.Tables[0].Rows)
{
TreeNode NewNode = new
TreeNode(row["CategoryName"].ToString(),
row["CategoryID"].ToString());
NewNode.PopulateOnDemand = true;
NewNode.SelectAction = TreeNodeSelectAction.Expand;
node.ChildNodes.Add(NewNode);
}
}
}
void PopulateProducts(TreeNode node)
{
SqlCommand sqlQuery = new SqlCommand();
if ((Session["typeorder"] == null) || (Session["typeorder"].ToString() == "All"))
{
sqlQuery.CommandText = "Select ProductName From Products " +
" Where CategoryID = @categoryid";
sqlQuery.Parameters.Add("@categoryid", SqlDbType.Int).Value =
node.Value;
}
else
{
sqlQuery.CommandText = "Select ProductName From Products " +
" Where CategoryID = @categoryid";
sqlQuery.Parameters.Add("@categoryid", SqlDbType.Int).Value =
node.Value;
}
DataSet ResultSet = RunQuery(sqlQuery);
if (ResultSet.Tables.Count > 0)
{
foreach (DataRow row in ResultSet.Tables[0].Rows)
{
TreeNode NewNode = new
TreeNode(row["ProductName"].ToString(),row["ProductName"].ToString(), null, "test.aspx?id=" + row["ProductName"].ToString(), "_blank");
NewNode.PopulateOnDemand = false;
NewNode.SelectAction = TreeNodeSelectAction.Expand;
node.ChildNodes.Add(NewNode);
}
}
}
private DataSet RunQuery(SqlCommand sqlQuery)
{
string connectionString =
ConfigurationManager.ConnectionStrings
["NorthwindConnectionString"].ConnectionString;
SqlConnection DBConnection =
new SqlConnection(connectionString);
SqlDataAdapter dbAdapter = new SqlDataAdapter();
dbAdapter.SelectCommand = sqlQuery;
sqlQuery.Connection = DBConnection;
DataSet resultsDataSet = new DataSet();
try
{
dbAdapter.Fill(resultsDataSet);
}
catch
{
labelStatus.Text = "Unable to connect to SQL Server.";
}
return resultsDataSet;
}
protected void submitbtn_Click(object sender, EventArgs e)
{
if (TreeView1.CheckedNodes.Count > 0)
{
Label1.Text = "你选择了:<br>";
ArrayList arraystr = new ArrayList();
foreach (TreeNode node in TreeView1.CheckedNodes)
{
arraystr.Add(node);
}
if (Session["selectednodes"] != null)
{
ArrayList arraystrswitch = new ArrayList();
arraystrswitch = (ArrayList)Session["selectednodes"];
for (int m = 0; m < arraystr.Count; m++)
{
arraystrswitch.Add((TreeNode)arraystr[m]);
}
Session["selectednodes"] = arraystrswitch;
}
else
{
Session["selectednodes"] = arraystr;
}
for(int k=0;k<arraystr.Count;k++)
{
Label1.Text += ((TreeNode)arraystr[k]).Value + "<br>";
}
}
else
{
if (Session["selectednodes"] != null)
{
//Label1.Text = Session["selectednodes"].ToString();
}
else
{
Label1.Text = "你没有选择任何内容！";
}
}
}
protected void Button1_Click(object sender, EventArgs e)
{
//DropDownList1.SelectedValue.ToString();
//TreeView1.CollapseAll();
Session["typeorder"] = DropDownList1.SelectedItem.Value;
Response.Redirect("Default3.aspx");
}
protected void Button2_Click(object sender, EventArgs e)
{
Session["selectednodes"] = "";
Label1.Text = "";
}
}