用ASP.NET AJAX实现无刷新多个DropDownList的动态联动

Posted on 2007-02-13 14:47 Eason 阅读(1949) 评论(0) 收藏举报

Default2.aspx

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="DDLajax.aspx.cs" Inherits="Default2" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<title>DDLajax</title>

</head>

<body>

<div>

<asp:ScriptManager ID="ScriptManager1" runat="server">

</asp:ScriptManager>

<br />

 </div>

<asp:UpdatePanel ID="UpdatePanel1" runat="server">

<asp:DropDownList ID="DropDownList1" runat="server" OnSelectedIndexChanged="DropDownList1_SelectedIndexChanged"

Width="233px">

</asp:DropDownList><br />

<asp:DropDownList ID="DropDownList2" runat="server" OnSelectedIndexChanged="DropDownList2_SelectedIndexChanged"

Width="233px">

</asp:DropDownList><br />

<br />

<asp:Label ID="Label1" runat="server" Text="Label" Width="234px"></asp:Label>

</ContentTemplate>

</asp:UpdatePanel>

<br />

<marquee>This is a trace message that marces across the bottom of the screen.</marquee>

</form>

</body>

</html>

Default2.cs

using System;

using System.Data;

using System.Configuration;

using System.Collections;

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 Default2 : System.Web.UI.Page

{

protected void Page_Load(object sender, EventArgs e)

{

DropDownList1.AutoPostBack = true;

DropDownList2.AutoPostBack = true;

if (!IsPostBack)

{

DropDownList1.Items.Add("Please Select Country");

DropDownList2.Items.Add("Please Select State");

DataRead("Select Country_ID, Country_Name from Country", DropDownList1);

DropDownList2.Enabled = false;

Label1.Text = "";

}

else if (DropDownList1.SelectedIndex == 0)

DropDownList2.Enabled = false;

}

protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)

{

DropDownList2.Items.Clear();

DropDownList2.Items.Add("Please Select State");

if (DropDownList1.SelectedIndex == 0)

DropDownList2.Enabled = false;

else

{

DropDownList2.Enabled = true;

DataRead("Select State_ID, State_Name from State where State_Country = " + DropDownList1.SelectedValue, DropDownList2);

}

Label1.Text = "";

}

protected void DropDownList2_SelectedIndexChanged(object sender, EventArgs e)

{

Label1.Text = "You select " + this.DropDownList2.SelectedItem + ", " + this.DropDownList1.SelectedItem;

if (DropDownList2.SelectedIndex == 0)

Label1.Text = "";

}

protected void DataRead(string Sqlstr, DropDownList ddl)

{

SqlConnection conn = new SqlConnection("server=localhost;database=DropDownList;uid=sa;pwd=sa");

conn.Open();

SqlCommand com = new SqlCommand(Sqlstr, conn);

SqlDataReader sr = null;

sr = com.ExecuteReader();

while (sr.Read())

ddl.Items.Add(new ListItem(sr[1].ToString(),sr[0].ToString()));

conn.Close();

}

数据库

State_ID    State_Name                                         State_Country
----------- -------------------------------------------------- -------------
1           NewYork                                            1
2           Carifornia                                         1
3           Shanghai                                           2
4           Beijing                                            2
5           Tokyo                                              3
6           Osaka                                              3

(6 row(s) affected)

Country_ID Country_Name
----------- --------------------------------------------------
1           US
2           China
3           Japan

(3 row(s) affected)

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用ASP.NET AJAX实现无刷新多个DropDownList的动态联动