个人学习代码保存:例7.ListBox小代码

前台代码：Default.aspx

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

<! 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:ListBox ID = " ListBox1 "  runat = " server "  SelectionMode = " Multiple " ></ asp:ListBox >& nbsp;
         < asp:Button ID = " Button2 "  runat = " server "  OnClick = " Button2_Click "  Text = " > "   />
         < asp:Button ID = " Button1 "  runat = " server "  OnClick = " Button1_Click "  Text = " >> "   />
         < asp:ListBox ID = " ListBox2 "  runat = " server "  SelectionMode = " Multiple " ></ asp:ListBox ></ div >
     </ form >
</ body >
</ html >

后台代码：

using  System;
using  System.Data;
using  System.Configuration;
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  _Default : System.Web.UI.Page 
{
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            this.ListBindData();
        }
    }
    public void ListBindData()
    {
        
        string connstr=ConfigurationManager.AppSettings["ConnectionString"].ToString();
        SqlConnection con = new SqlConnection(connstr);
        if (con.State.Equals(ConnectionState.Closed))
        {
            con.Open();
        }
        SqlCommand cmd = new SqlCommand("select * from guestbook",con);
        SqlDataReader sdr = cmd.ExecuteReader(CommandBehavior.CloseConnection);
        //这是第一种方法了
        //while (sdr.Read())
        //{
        //    ListBox1.Items.Add(new ListItem(sdr["title"].ToString(),sdr["id"].ToString()));
        //}
        ListBox1.DataSource = sdr;
        ListBox1.DataTextField = "title";
        ListBox1.DataValueField = "id";
        ListBox1.DataBind();
    }
    protected void Button1_Click(object sender, EventArgs e)
    {
        foreach (ListItem item in ListBox1.Items)
        {
            ListBox2.Items.Add(item);
           
        }
        ListBox1.Items.Clear();
    }
    protected void Button2_Click(object sender, EventArgs e)
    {
        ListBox2.Items.Add(ListBox1.SelectedItem);
        ListBox1.SelectedIndex = -1;
        ListBox2.SelectedIndex = -1;
    }
}