defaultcs.aspx.cs

Telerik是很大的第三方软件制造商

using System;
using System.Collections;
using System.ComponentModel;
using System.Data;
using System.Data.OleDb;
using System.Drawing;
using System.Web;
using System.Web.SessionState;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.HtmlControls;

namespace Telerik.CallbackExamplesCSharp.Functionality.PreservingControlFocus
{
	/// <summary>
	/// Summary description for DefaultCS.
	/// </summary>
	public class DefaultCS : System.Web.UI.Page
	{
		protected Telerik.WebControls.CallbackTextBox CallbackTextBox1;
		protected System.Web.UI.WebControls.Label Label2;
		protected System.Web.UI.WebControls.Label Label3;
		protected Telerik.WebControls.CallbackCheckBox cbSetFocus;
		protected System.Web.UI.WebControls.Image Image1;
		protected Telerik.WebControls.LoadingPanel LoadingPanel1;
		protected Telerik.WebControls.CallbackDropDownList ddlContinents;
		protected Telerik.WebControls.CallbackDropDownList ddlCountries;
		protected Telerik.WebControls.CallbackDropDownList ddlCities;
		protected System.Web.UI.WebControls.Label lbPath;
		protected Telerik.WebControls.CallbackTextBox CallbackTextBox2;
	
		private void Page_Load(object sender, System.EventArgs e)
		{			
			if (!Page.IsPostBack)
			{				
				LoadContinents();
				ResetControls();				
			}
		}

		#region Web Form Designer generated code
		override protected void OnInit(EventArgs e)
		{
			//
			// CODEGEN: This call is required by the ASP.NET Web Form Designer.
			//
			InitializeComponent();
			base.OnInit(e);
		}
		
		/// <summary>
		/// Required method for Designer support - do not modify
		/// the contents of this method with the code editor.
		/// </summary>
		private void InitializeComponent()
		{    
			this.ddlCities.SelectedIndexChanged += new System.EventHandler(this.ddlCities_SelectedIndexChanged);
			this.ddlCountries.SelectedIndexChanged += new System.EventHandler(this.ddlCountries_SelectedIndexChanged);
			this.ddlContinents.SelectedIndexChanged += new System.EventHandler(this.ddlContinents_SelectedIndexChanged);
			this.Load += new System.EventHandler(this.Page_Load);

		}
		#endregion

		private void LoadContinents()
		{
			string path = Server.MapPath("~/Callback/Data/Countries.mdb");
			OleDbConnection dbCon = new OleDbConnection ("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + path); 
			dbCon.Open();
			
			OleDbDataAdapter adapter = new OleDbDataAdapter("SELECT * FROM Continents", dbCon); 
			DataTable dt = new DataTable();
			adapter.Fill(dt);
			dbCon.Close();

			ddlContinents.DataTextField = "Name";
			ddlContinents.DataValueField = "ID";
			ddlContinents.DataSource = dt;
			ddlContinents.DataBind();			

			ddlContinents.Items.Insert(0, new ListItem(" - Select a continent - "));

			if (ddlContinents.SelectedIndex == -1)
			{
				ddlContinents.SelectedIndex = 0;
			}
		}
	
		private void ddlContinents_SelectedIndexChanged(object sender, System.EventArgs e)
		{
			if (ddlContinents.SelectedIndex > 0)
			{
				LoadCountries(ddlContinents.SelectedItem.Value);
				LoadCities(ddlCountries.SelectedItem.Value);
				if (cbSetFocus.Checked)
				{
					ddlContinents.SetFocus(ddlCountries.ClientID);		
				}
			}
			else
			{	
				ddlCountries.Enabled = false;
				ddlCities.Enabled = false;
				ResetControls();				
			}
			UpdatePath();
		}

		private void ResetControls()
		{
			if (ddlCountries.Items.Count == 0)
			{				
				ddlCountries.Items.Insert(0, new ListItem("- Select a country - ", "-1"));
			}
			ddlCities.SelectedIndex = 0;
			if (ddlCities.Items.Count == 0)
			{				
				ddlCities.Items.Insert(0, new ListItem("- Select a city - ", "-1"));
			}
			ddlCities.SelectedIndex = 0;
		}

		private void UpdatePath()
		{
			lbPath.Text = string.Empty;
			if (ddlContinents.SelectedIndex > 0)
			{
				lbPath.Text += ddlContinents.SelectedItem.Text;
				if (ddlCountries.SelectedIndex > 0)
				{
					lbPath.Text += " > " + ddlCountries.SelectedItem.Text;

					if (ddlCities.SelectedIndex > 0)
					{
						lbPath.Text += " > " + ddlCities.SelectedItem.Text;
					}
				}
			}
		}

		private void LoadCountries(string selectedValue)
		{
			if (selectedValue != "-1") 
			{
				string path = Server.MapPath("~/Callback/Data/Countries.mdb");
				OleDbConnection dbCon = new OleDbConnection ("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + path); 
				dbCon.Open();
			
				OleDbDataAdapter adapter = new OleDbDataAdapter("SELECT * FROM Countries WHERE ContinentID = " + selectedValue, dbCon);
				DataTable dt = new DataTable();
				adapter.Fill(dt);
				dbCon.Close();

				ddlCountries.DataTextField = "Name";
				ddlCountries.DataValueField = "ID";
				ddlCountries.DataSource = dt;
				ddlCountries.DataBind();

				ddlCountries.Enabled = true;

				ddlCountries.Items.Insert(0, new ListItem("- Select a country -", "-1"));

				if (ddlCountries.SelectedIndex == -1)
				{
					ddlCountries.SelectedIndex = 0;
				}
			}
		}

		private void LoadCities(string selectedValue)
		{	
			if (selectedValue != "-1")
			{
				string path = Server.MapPath("~/Callback/Data/Countries.mdb");
				OleDbConnection dbCon = new OleDbConnection ("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + path); 
				dbCon.Open();
			
				OleDbDataAdapter adapter = new OleDbDataAdapter("SELECT * FROM Cities WHERE CountryID = " + selectedValue, dbCon); 
				DataTable dt = new DataTable();
				adapter.Fill(dt);
				dbCon.Close();

				ddlCities.DataTextField = "Name";
				ddlCities.DataValueField = "ID";
				ddlCities.DataSource = dt;
				ddlCities.DataBind();			

				ddlCities.Items.Insert(0, new ListItem("- Select a city - ", "-1"));

				ddlCities.Enabled = true;

				if (ddlCities.SelectedIndex == -1)
				{
					ddlCities.SelectedIndex = 0;
				}			
			}			
			else
			{
				if (ddlCities.Items.Count == 0)
				{				
					ddlCities.Items.Insert(0, new ListItem("- Select a city - ", "-1"));
				}
				ddlCities.SelectedIndex = 0;
				ddlCities.Enabled = false;
			}
		}

		private void ddlCountries_SelectedIndexChanged(object sender, System.EventArgs e)
		{
			if (ddlCountries.SelectedIndex > 0)
			{
				LoadCities(ddlCountries.SelectedItem.Value);
				if (cbSetFocus.Checked)
				{
					ddlContinents.SetFocus(ddlCities.ClientID);		
				}
			}
			UpdatePath();
		}

		private void ddlCities_SelectedIndexChanged(object sender, System.EventArgs e)
		{
			UpdatePath();			
			if (cbSetFocus.Checked)
			{
				ddlCities.SetFocus(ddlContinents.ClientID);		
			}
		}
		
	}
}