两个DropDownList在Repeater、DataList、DataGrid内的连动和冒泡事件(BubbleEvent)

两个DropDownList在Repeater、DataList、DataGrid内的连动和冒泡事件(BubbleEvent)
        问题: http://community.csdn.net/Expert/topic/4670/4670056.xml?temp=3.944033E-02
        刚看第一眼觉得在第一个DDL的SelectedIndexChanged事件内绑定第二个DDL就ok了，页面上写或者ItemDataBound内写事件挂接代码都可以。打开VS写测试却发现有点障碍哦，
在SelectedIndexChanged内要知道去绑定哪个行哪个列的DDL要费些周折。
只有从DDL一级一级的向上找Parent最后找到DataGridItem，再利用其ItemIndex定位到行然后FindControl到要绑定的DDL，最终可以实现，好像比较累哦。
        随又想到DataGrid的ItemCommand事件，但发现WebControl内只有Button ImageButton LinkButton有CommandName属性和 CommandArgument属性，并可以将事件上浮（冒泡）.DropDownList先天不足！真是郁闷~~~~~ 能不能自己改造呢？动手试试就知道了。

[Copy to clipboard]

using System;
using System.ComponentModel;
using System.Web.UI.WebControls;
namespace AspxBoy.WebTest.MyControls
{
/// <summary>
/// CommandableDropDownList 的摘要说明。
/// </summary>
public class CommandableDropDownList : DropDownList
{
#region 字段
#endregion
#region 属性
[
Browsable(true),
DefaultValue("")
]
public string CommandName
{
get
{
return ViewState["CommandName"] == null ? String.Empty : ViewState["CommandName"].ToString();
}
set
{
ViewState["CommandName"] = value;
}
}
[
Browsable(true),
DefaultValue("")
]
public string CommandArgument
{
get
{
return ViewState["CommandArgument"] == null ? String.Empty : ViewState["CommandArgument"].ToString();
}
set
{
ViewState["CommandArgument"] = value;
}
}
#endregion
#region 构造器
public CommandableDropDownList()
{
//
// TODO: 在此处添加构造函数逻辑
//
}
#endregion
#region 事件
private static object _commandEvent = new object();
public event CommandEventHandler SelectedChangedCommand
{
add
{
Events.AddHandler(_commandEvent,value);
}
remove
{
Events.RemoveHandler(_commandEvent,value);
}
}
protected virtual void OnCommand(CommandEventArgs e)
{
CommandEventHandler commandHander = (CommandEventHandler)Events[_commandEvent];
if(commandHander != null)
{
commandHander(this,e);
}
else
{
base.RaiseBubbleEvent(this,e);
}
}
#endregion
#region 覆写的方法
protected override void OnSelectedIndexChanged(EventArgs e)
{
base.OnSelectedIndexChanged (e);
if(this.AutoPostBack)
{
CommandEventArgs args = new CommandEventArgs(this.CommandName, this.CommandArgument);
OnCommand(args);
}
}
#endregion
}
}

就这样了，然后在模板列内放置该控件，DataGrid的ItemCommand事件内就可以处理到CommandName为你指定的值的操作拉
后台代码如下：

[Copy to clipboard]

using System;
using System.Collections;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Web;
using System.Web.SessionState;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.HtmlControls;
using AspxBoy.WebTest.MyControls;
namespace AspxBoy.WebTest
{
/// <summary>
/// TwoDropDownListInDataGridEx 的摘要说明。
/// </summary>
public class TwoDropDownListInDataGridEx : System.Web.UI.Page
{
protected System.Web.UI.WebControls.DataGrid dg;
private void Page_Load(object sender, System.EventArgs e)
{
// 在此处放置用户代码以初始化页面
if(!Page.IsPostBack)
{
BindGrid();
}
}
private void BindGrid()
{
dg.DataSource =  new string[]{"a","a","a","a","a","a"};
dg.DataBind();
}
#region Web 窗体设计器生成的代码
override protected void OnInit(EventArgs e)
{
//
// CODEGEN: 该调用是 ASP.NET Web 窗体设计器所必需的。
//
InitializeComponent();
base.OnInit(e);
}
/// <summary>
/// 设计器支持所需的方法 - 不要使用代码编辑器修改
/// 此方法的内容。
/// </summary>
private void InitializeComponent()
{
this.dg.ItemCommand += new System.Web.UI.WebControls.DataGridCommandEventHandler(this.dg_ItemCommand);
this.dg.ItemDataBound += new System.Web.UI.WebControls.DataGridItemEventHandler(this.dg_ItemDataBound);
this.Load += new System.EventHandler(this.Page_Load);
}
#endregion
private ICollection GetProvinceCollection()
{
return  new string[]{"陕西","辽宁"};
}
private ICollection GetCityCollection(string provinceName)
{
if(provinceName == "陕西")
{
return new string[]{"西安","宝鸡","渭南","汉中"};
}
else if(provinceName == "辽宁")
{
return new string[]{"沈阳","鞍山","抚顺","本溪"};
}
else
{
return null;
}
}
private void dg_ItemDataBound(object sender, System.Web.UI.WebControls.DataGridItemEventArgs e)
{
if(e.Item.ItemType == ListItemType.AlternatingItem || e.Item.ItemType == ListItemType.Item)
{
Label lbl = e.Item.FindControl("lbl_no") as Label;
if( lbl != null )
{
lbl.Text = (e.Item.ItemIndex + 1).ToString();
}
CommandableDropDownList ddl_province = e.Item.FindControl("ddl_province") as CommandableDropDownList;
if(ddl_province != null)
{
ddl_province.DataSource = GetProvinceCollection();
ddl_province.DataBind();
}
CommandableDropDownList ddl_city = e.Item.FindControl("ddl_city") as CommandableDropDownList;
if(ddl_city != null)
{
ddl_city.DataSource = GetCityCollection(ddl_province.SelectedValue);
ddl_city.DataBind();
}
}
}
private void dg_ItemCommand(object source, System.Web.UI.WebControls.DataGridCommandEventArgs e)
{
if(e.CommandName == "ProvinceChange")
{
string currentProvinceName = String.Empty;
int index = e.Item.ItemIndex;
CommandableDropDownList ddl = this.dg.Items[index].FindControl("ddl_province") as CommandableDropDownList;
if(ddl != null)
{
currentProvinceName = ddl.SelectedValue;
}
ddl = this.dg.Items[index].FindControl("ddl_city") as CommandableDropDownList;
if(ddl != null)
{
ICollection cityCollection = GetCityCollection(currentProvinceName);
if(cityCollection != null)
{
ddl.DataSource = cityCollection;
ddl.DataBind();
}
}
}
}
}
}

aspx代码如下

[Copy to clipboard]

<br>若不使用自定义控件，的代码如下（比较累哦<img src="/default/index/img?u=L2RlZmF1bHQvaW5kZXgvaW1nP3U9YUhSMGNITTZMeTkzZDNjdVkyNWliRzluY3k1amIyMHZSVzF2ZEdsamIyNXpMMk55ZVY5emJXbHNaUzVuYVdZPQ==" border="0" alt="两个DropDownList在Repeater、DataList、DataGrid内的连动和冒泡事件(BubbleEvent)" title="两个DropDownList在Repeater、DataList、DataGrid内的连动和冒泡事件(BubbleEvent)">）：
<div title=">-点此复制到剪贴板-<" style="color: rgba(0, 0, 255, 1); text-align: left; text-decoration: underline">[Copy to clipboard] </div>
<textarea>using System;
using System.Collections;
using System.ComponentModel;
using System.Data;
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 AspxBoy.WebTest
{
/// <summary>
/// TwoDropDownListInDataGrid 的摘要说明。
/// </summary>
public class TwoDropDownListInDataGrid : System.Web.UI.Page
{
protected System.Web.UI.WebControls.DataGrid dg;
private void Page_Load(object sender, System.EventArgs e)
{
// 在此处放置用户代码以初始化页面
if(!Page.IsPostBack)
{
BindGrid();
}
}
private void BindGrid()
{
dg.DataSource =  new string[]{"a","a","a","a","a","a"};
dg.DataBind();
}
private ICollection GetProvinceCollection()
{
return  new string[]{"陕西","辽宁"};
}
private ICollection GetCityCollection(string provinceName)
{
if(provinceName == "陕西")
{
return new string[]{"西安","宝鸡","渭南","汉中"};
}
else if(provinceName == "辽宁")
{
return new string[]{"沈阳","鞍山","抚顺","本溪"};
}
else
{
return null;
}
}
#region Web 窗体设计器生成的代码
override protected void OnInit(EventArgs e)
{
//
// CODEGEN: 该调用是 ASP.NET Web 窗体设计器所必需的。
//
InitializeComponent();
base.OnInit(e);
}
/// <summary>
/// 设计器支持所需的方法 - 不要使用代码编辑器修改
/// 此方法的内容。
/// </summary>
private void InitializeComponent()
{
this.dg.ItemCreated += new System.Web.UI.WebControls.DataGridItemEventHandler(this.dg_ItemCreated);
this.dg.ItemDataBound += new System.Web.UI.WebControls.DataGridItemEventHandler(this.dg_ItemDataBound);
this.Load += new System.EventHandler(this.Page_Load);
}
#endregion
private void dg_ItemDataBound(object sender, System.Web.UI.WebControls.DataGridItemEventArgs e)
{
if(e.Item.ItemType == ListItemType.AlternatingItem || e.Item.ItemType == ListItemType.Item)
{
Label lbl = e.Item.FindControl("lbl_no") as Label;
if( lbl != null )
{
lbl.Text = (e.Item.ItemIndex + 1).ToString();
}
DropDownList ddl_province = e.Item.FindControl("ddl_province") as DropDownList;
if(ddl_province != null)
{
ddl_province.DataSource = GetProvinceCollection();
ddl_province.DataBind();
}
DropDownList ddl_city = e.Item.FindControl("ddl_city") as DropDownList;
if(ddl_city != null)
{
ddl_city.DataSource = GetCityCollection(ddl_province.SelectedValue);
ddl_city.DataBind();
}
}
}
private void dg_ItemCreated(object sender, System.Web.UI.WebControls.DataGridItemEventArgs e)
{
if(e.Item.ItemType == ListItemType.AlternatingItem || e.Item.ItemType == ListItemType.Item)
{
DropDownList ddl = e.Item.FindControl("ddl_province") as DropDownList;
if(ddl != null)
{
ddl.AutoPostBack = true;
ddl.SelectedIndexChanged += new EventHandler(ddl_SelectedIndexChanged);
}
}
}
protected void ddl_SelectedIndexChanged(object o , EventArgs e)
{
DropDownList ddl = o as DropDownList;
if(ddl != null)
{
TableCell cell =  ddl.Parent as TableCell;
if(cell != null)
{
DataGridItem dgItem = cell.Parent as DataGridItem;
if(dgItem != null)
{
string currentProvinceName = String.Empty;
int index = dgItem.ItemIndex;
ddl = this.dg.Items[index].FindControl("ddl_province") as DropDownList;
if(ddl != null)
{
currentProvinceName = ddl.SelectedValue;
}
ddl = this.dg.Items[index].FindControl("ddl_city") as DropDownList;
if(ddl != null)
{
ICollection cityCollection = GetCityCollection(currentProvinceName);
if(cityCollection != null)
{
ddl.DataSource = cityCollection;
ddl.DataBind();
}
}
}
}
}
}
}
}

aspx代码如下

[Copy to clipboard]

   另：
      关于在用户控件内事件上浮（冒泡）的例子请访问下面的地址：
http://authors.aspalliance.com/hmcheung/Articles/030331/Default.aspx
      在设计自定义复合控件时将控件事件上浮（冒泡）请访问：
http://msdn.microsoft.com/library/chs/default.asp?url=/library/CHS/cpguide/html/cpconeventbubblingcontrolsample.asp