要求：
新建 ProvinceCity用户控件。在该控件 中增加一个Button1按钮。
在Demo1.aspx页面中引用 ProvincCity控件。并且加入button1和Lable1控件。
当点击Demo1中的button时，在lable1中显示用户在provinceCity控件中选择的省和市。
使用两种方法，实现当点击用户控件中的button1时，让demo1中的lable显示ProvinceCity控件中 drowpdownList2中选中的内容。
在Demo2中直接调用用户控件。
用户控件：
citySelect.ascx文件：
<%@ Control Xlanguage="C#" AutoEventWireup="true" CodeBehind="citySelect.ascx.cs" Inherits="用户自定义控件.citySelect" %>
省份：<asp:DropDownList ID="DropDownList1" runat="server"
AutoPostBack="True" Xonselectedindexchanged="DropDownList1_SelectedIndexChanged">
</asp:DropDownList>
城市：<asp:DropDownList ID="DropDownList2" runat="server">
</asp:DropDownList>
<asp:Button ID="Button1" runat="server" Text="获取页面中的label为其值"
Xonclick="Button1_Click" />
citySelect.ascx.cs文件：
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data.SqlClient;
using System.Data;
namespace 用户自定义控件
{
public partial class citySelect : System.Web.UI.UserControl
{
public event CitySelectHandler GetCitySelect; //用委托定义对应类型的事件
public string GetProvinceCity
{
get { return "省份是：" + this.DropDownList1.SelectedItem.Text + " 城市是：" + this.DropDownList2.SelectedItem.Text; }
}
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
bindprovince();
}
}
private void bindprovince()
{
string constr = System.Configuration.ConfigurationManager.ConnectionStrings["con"].ConnectionString;
using (SqlConnection con = new SqlConnection(constr))
{
string sql = "select provinceID,province from province";
using (SqlCommand cmd = new SqlCommand(sql, con))
{
SqlDataAdapter adapter = new SqlDataAdapter(cmd);
DataTable dt = new DataTable();
adapter.Fill(dt);
con.Open();
DropDownList1.DataSource = dt;
DropDownList1.DataTextField = "province";
DropDownList1.DataValueField = "provinceID";
DropDownList1.DataBind();
}
}
}
protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
{
this.DropDownList2.Items.Clear();
string Pid = this.DropDownList1.SelectedValue;
string sql = "select cityId,city from city where father=@Pid";
SqlParameter P1 = new SqlParameter("@Pid", Pid);
string constr = System.Configuration.ConfigurationManager.ConnectionStrings["con"].ConnectionString;
using (SqlConnection con = new SqlConnection(constr))
{
using (SqlCommand cmd = new SqlCommand(sql, con))
{
cmd.Parameters.Add(P1);
SqlDataAdapter adapter = new SqlDataAdapter(cmd);
DataTable dt = new DataTable();
adapter.Fill(dt);
con.Open();
DropDownList2.DataSource = dt;
DropDownList2.DataTextField = "city";
DropDownList2.DataValueField = "cityID";
DropDownList2.DataBind();
}
}
}
protected void Button1_Click(object sender, EventArgs e)
{
//Label lbl = this.Parent.FindControl("Label1") as Label;
//lbl.Text = this.DropDownList2.SelectedItem.Text;
//当用户控件中的button1按钮被单击的时候，激发GetCitySelect事件
if (GetCitySelect!=null)
{
GetCitySelect(this, DropDownList2.SelectedItem.Text);
}
}
}
public delegate void CitySelectHandler(object sender,string selectCity); //委托
}
Demo1.asox.cs文件：
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
namespace 用户自定义控件
{
public partial class Demo1 : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
//增加用户控件citySelect.ascx的事件处理程序
this.citySelect1.GetCitySelect += new CitySelectHandler(citySelect1_GetCitySelect);
}
//按Tab建实例化委托，并生成一个方法。
void citySelect1_GetCitySelect(object sender, string selectCity)
{
this.Label1.Text = selectCity;
this.TextBox1.Text = selectCity;
}
protected void Button1_Click(object sender, EventArgs e)
{
#region 方法一 FindControl方法
//DropDownList ddl1 = this.citySelect1.FindControl("DropDownList1") as DropDownList;
//DropDownList ddl2 = this.citySelect1.FindControl("DropDownList2") as DropDownList;
//this.Label1.Text = "省份是：" + ddl1.SelectedItem.Text + " 城市是：" + ddl2.SelectedItem.Text;
#endregion
#region 方法二 在用户控件中定义属性，这里调用属性获取省市
this.Label1.Text = this.citySelect1.GetProvinceCity;
#endregion
}
}
}
Demo2.aspx文件：
<%@ Page Xlanguage="C#" AutoEventWireup="true" CodeBehind="Demo2.aspx.cs" Inherits="用户自定义控件.Demo2" %>
<%@ Register src="citySelect.ascx" tagname="citySelect" tagprefix="uc1" %>
<!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></title>
</head>
<body>
<form id="form1" runat="server">
<div>
<uc1:citySelect ID="citySelect1" runat="server" />
</div>
</form>
</body>
</html>
Demo2.aspx.cs文件：
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
namespace 用户自定义控件
{
public partial class Demo2 : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
this.citySelect1.GetCitySelect += new CitySelectHandler(citySelect1_GetCitySelect);
}
void citySelect1_GetCitySelect(object sender, string selectCity)
{
this.Response.Write(selectCity);
}
}
}