1. selectedIndex——指的是dropdownlist中选项的索引，为int，从0开始，可读可写
2. selectedItem——指的是选中的dropdownlist中选项，为ListItem，只读不写
3. selectedValue——指的是选中的dropdownlist中选项的值，为string， 只读不写
4. selectedItem.Text——指的是选中的dropdownlist中选项的文本内容，与selectedItem的值一样为string，可读可写
5. selectedItem.value——指的是选中的dropdownlist中选项的值，与selectedValue的值一样，为string，可读可写
光看文字可能不太理解，我也是通过程序来加深理解的，下面举个例子：
前台代码：
- <%@ Page Language="C#" AutoEventWireup="true" CodeFile="dropdown.aspx.cs" Inherits="dropdown" %>
-
- <!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">
- <div>
- <asp:DropDownList ID="DropDownList1" runat="server">
- <asp:ListItem Value="1">北京</asp:ListItem>
- <asp:ListItem Value="2">上海</asp:ListItem>
- <asp:ListItem Value="3">广州</asp:ListItem>
- </asp:DropDownList>
- <asp:Button ID="Button1" runat="server" OnClick="Button1_Click" Text="check" /><br />
- <asp:Label ID="Label1" runat="server" Text=""></asp:Label>
- <br />
- <asp:Label ID="Label2" runat="server" Text=""></asp:Label>
- <br />
- <asp:Label ID="Label3" runat="server" Text=""></asp:Label><br />
- <asp:Label ID="Label4" runat="server" Text=""></asp:Label>
- <br />
- <asp:Label ID="Label5" runat="server" Text=""></asp:Label>
-
- </div>
- </form>
- </body>
- </html>
后台代码：
- 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;
-
- public partial class dropdown : System.Web.UI.Page
- {
- protected void Page_Load(object sender, EventArgs e)
- {
-
- }
- protected void Button1_Click(object sender, EventArgs e)
- {
- Label1.Text = "selectedIndex=" + DropDownList1.SelectedIndex;
- Label2.Text = "selectedItem=" + DropDownList1.SelectedItem;
- Label3.Text = "selectedValue=" + DropDownList1.SelectedValue;
- Label4.Text = "selectedItem.text=" + DropDownList1.SelectedItem.Text;
- Label5.Text = "selectedItem.value=" + DropDownList1.SelectedItem.Value;
- }
- }
运行效果如下：
