asp.net 中如何对<dropdownlist>实现多级联动

asp.net 中如何对<dropdownlist>实现多级联动，并且点下面的按钮点击的时候，我还想把它的值给取出来描述：首先，页面加载的时候出现一个<dropdownlist>，并从数据库中查出数据，把值绑定到<dropdownlist> 当我选中<dropdownlist>的值时，把它的子节点的值查出来，如果有值的话，就为他生成一个<dropdownlist> 并把查出来的值给他绑定上。如果选中第二个<dropdownlist>的时候，把它的子节点的值查出来，如果有值的话，就为他生成一个<dropdownlist> 并把查出来的值给他绑定上依次类推，总之他有多少子节点，我们就为他动态生成<dropdownlist>，并且绑定。最下面的按钮点击的时候，我还想把它的值给取出来，（只要有<dropdownlist>。我都想取他的值）请大家指教，多多帮忙，谢谢。

解决方案 »

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既然是无限级，干嘛用非用N个dropdownlist来做
吧dropdowlist的AutoPostBack="True"
然后在onselectedindexchanged事件里面写你要实现的东西就行了
http://www.51aspx.com/CV/myAjaxDropdownlist/
http://www.51aspx.com/S/%E8%81%94%E5%8A%A8.html
参考:http://www.cnblogs.com/insus/articles/1411016.html
protected void course_SelectedIndexChanged(object sender, System.EventArgs e)
{
    //根據課程顯示該課程的廠班別
    Listfac();
    ListClass();
    setfocu("course");
}
用ASP.NET AJAX实现无刷新多个DropDownList的动态联动
DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> 字串4<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>DDLajaxtitle>
head>
<body>
<form id="form1" runat="server">
<div>
<asp:ScriptManager ID="ScriptManager1" runat="server">
asp:ScriptManager>
<br />
 div>
<asp:UpdatePanel ID="UpdatePanel1" runat="server">
<ContentTemplate>
<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 />字串8
Default2.cs 字串4using 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; 字串5public partial class Default2 : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
DropDownList1.AutoPostBack = true;
DropDownList2.AutoPostBack = true; 字串7if (!IsPostBack)
{
DropDownList1.Items.Add("Please Select Country");
DropDownList2.Items.Add("Please Select State");字串5DataRead("Select Country_ID, Country_Name from Country", DropDownList1); 字串8DropDownList2.Enabled = false;
Label1.Text = "";
}
else if (DropDownList1.SelectedIndex == 0)
DropDownList2.Enabled = false;
} 字串7protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
{
DropDownList2.Items.Clear();
DropDownList2.Items.Add("Please Select State");字串7
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 = "";
} 字串1protected void DropDownList2_SelectedIndexChanged(object sender, EventArgs e)
{
Label1.Text = "You select " this.DropDownList2.SelectedItem ", " this.DropDownList1.SelectedItem;
if (DropDownList2.SelectedIndex == 0)
Label1.Text = "";
} 字串8protected 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();
}
}字串6数据库字串7
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)字串4Country_ID Country_Name
----------- --------------------------------------------------
1 US
2 China
3 Japan 字串6(3 row(s) affected)字串5
<asp:Label ID="Label1" runat="server" Text="Label" Width="234px">asp:Label>
ContentTemplate>
asp:UpdatePanel>
<br />
<br />
<br />
<br />
<marquee>This is a trace message that marces across the bottom of the screen.marquee>
form>
body>
html>
曾经,我们为了实现dropdownlist的无刷新联动绞尽脑汁，最后还不得不写大量的js代码来实现。，如今，
微软的atlas,可以让我们摆脱写大段JS代码来实现dropdownlist的无刷新联动，而且简单易懂。一、拖入一个dropdownlist1控件，二、在drp.aspx页面上放一个atlas的核心控件updatepanel1,给updatepanel1增加一个scriptmanager控件，
         注意scriptmanager的属性 EnablePartialRendering必须设为"True"，一个页面只能有一个scriptmanager控件三、将一个dropdownlist2控件拖入到updatepanel1区域内，并将其ispostback属性设为true  ,
         现在设置updatepanel1的属性triggers：updatepanel1 的control指定为dropdownlist1，proprety指定为selectvalue;四、再放入一个updatepanel2，在里面再放一个dropdownlist3，
        现在设置updatepanel2的属性triggers：updatepanel2 的control指定为updatepanel1，proprety指定为triggers;         因为dropdownlist3的数据源是dropdownlist2的索引改变而来,而dropdownlist2在updatepanel1里面,所以这里
         是设置updatepanel2 的control为updatepanel1，proprety指定为triggers;此时，所有的属性基本设置完毕了，开始写服务器端的代码DropDownList1的索引改变事件
protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
    {
        string strConn = "data source=(local);uid=sa;pwd=sundun;database=tempdb";
        SqlConnection conn = new SqlConnection(strConn);
        SqlDataAdapter da = new SqlDataAdapter("select * from test where bianhao='"+DropDownList1.SelectedValue+"'", conn);
        DataSet ds = new DataSet();
        da.Fill(ds);
        DropDownList2.DataSource = ds.Tables[0];
        DropDownList2.DataTextField = "name";
        DropDownList2.DataValueField = "name";
        DropDownList2.DataBind();

    }DropDownList2的索引改变事件
protected void DropDownList2_SelectedIndexChanged(object sender, EventArgs e)
    {
        string strConn = "data source=(local);uid=sa;pwd=sundun;database=tempdb";
        SqlConnection conn = new SqlConnection(strConn);
        SqlDataAdapter da = new SqlDataAdapter("select * from test where name='" + DropDownList2.SelectedValue + "'", conn);
        DataSet ds = new DataSet();
        da.Fill(ds);        DropDownList3.DataSource = ds.Tables[0];        DropDownList3.DataTextField = "address";
        DropDownList3.DataValueField = "address";
        DropDownList3.DataBind();
        }创建数据表SQL
if exists (select * from dbo.sysobjects where id = object_id(N'[dbo].[test]') and OBJECTPROPERTY(id, N'IsUserTable') = 1)
drop table [dbo].[test]
GOCREATE TABLE [dbo].[test] (
[id] [int] IDENTITY (1, 1) NOT NULL ,
[name] [char] (10) COLLATE Chinese_PRC_CI_AS NULL ,
[address] [char] (10) COLLATE Chinese_PRC_CI_AS NULL ,
[bianhao] [char] (10) COLLATE Chinese_PRC_CI_AS NULL
) ON [PRIMARY]
GO全部文件代码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 Drp : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {    }
    protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
    {
        string strConn = "data source=(local);uid=sa;pwd=sundun;database=tempdb";
        SqlConnection conn = new SqlConnection(strConn);
        SqlDataAdapter da = new SqlDataAdapter("select * from test where bianhao='"+DropDownList1.SelectedValue+"'", conn);
        DataSet ds = new DataSet();
        da.Fill(ds);
        DropDownList2.DataSource = ds.Tables[0];
        DropDownList2.DataTextField = "name";
        DropDownList2.DataValueField = "name";
        DropDownList2.DataBind();

    }
    protected void DropDownList2_SelectedIndexChanged(object sender, EventArgs e)
    {
        string strConn = "data source=(local);uid=sa;pwd=sundun;database=tempdb";
        SqlConnection conn = new SqlConnection(strConn);
        SqlDataAdapter da = new SqlDataAdapter("select * from test where name='" + DropDownList2.SelectedValue + "'", conn);
        DataSet ds = new DataSet();
        da.Fill(ds);        DropDownList3.DataSource = ds.Tables[0];        DropDownList3.DataTextField = "address";
        DropDownList3.DataValueField = "address";
        DropDownList3.DataBind();
        }
}客户端代码:<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Drp.aspx.cs" Inherits="Drp" %><!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">
        <atlas:ScriptManager ID="ScriptManager1" runat="server" EnablePartialRendering="True">
        </atlas:ScriptManager>
        <asp:DropDownList ID="DropDownList1" runat="server" AutoPostBack="True" OnSelectedIndexChanged="DropDownList1_SelectedIndexChanged">
            <asp:ListItem>01</asp:ListItem>
            <asp:ListItem>02</asp:ListItem>
            <asp:ListItem>03</asp:ListItem>
        </asp:DropDownList>
        <atlas:UpdatePanel ID="UpdatePanel1" runat="server">
            <ContentTemplate>
                <asp:DropDownList ID="DropDownList2" runat="server" AutoPostBack="True" OnSelectedIndexChanged="DropDownList2_SelectedIndexChanged">
                </asp:DropDownList> 
            </ContentTemplate>
            <Triggers>
                <atlas:ControlValueTrigger ControlID="DropDownList1" PropertyName="SelectedValue" />
            </Triggers>
        </atlas:UpdatePanel>
        <atlas:UpdatePanel ID="UpdatePanel2" runat="server">
            <ContentTemplate>
        <asp:DropDownList ID="DropDownList3" runat="server">
        </asp:DropDownList>
            </ContentTemplate>
            <Triggers>
                <atlas:ControlValueTrigger ControlID="UpdatePanel1" PropertyName="Triggers" />
            </Triggers>
        </atlas:UpdatePanel>
    <div>
         

    </div>
           
    </form>
</body>
吧dropdowlist的AutoPostBack="True"
然后在onselectedindexchanged事件里面写你要实现的东西就行了
更正下9楼的说法,Atlas早就退出历史舞台了啊,哈哈
现在就叫 Ajax不用那个名字了啊不过9楼的方法可以,但是和lz说的动态生成还是有点区别的!!
这种方法，我觉得有问题，他页面加载的时候就要查询数据库，然后绑定下拉列表，比如默认选项是第1项
加载之后比如要选择第3项，经过AutoPostBack=True回传，页面再次加载的时候又显示的是第一项，而不是第3项。怎么办？
放在AjaxPanel中？
我的程序里边用的AjaxPanel
如果想只用AutoPostBack=True和onselectedindexchanged，不用其他控件，怎么搞？
动态添加dropdownlist或select同多文件上传
可以用webservces +ajax 很容易实现的