datareader读数据存列表中

gridview要自己绑定列
<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False">
    <Columns>
    <asp:TemplateField HeaderText="学号">
    <ItemTemplate >
    <%# ((visitor)Container.DataItem).Vid %>
    </ItemTemplate>
    </asp:TemplateField>
    <asp:TemplateField HeaderText="姓名">
    <ItemTemplate>
    <%# ((visitor)Container.DataItem).Vname %>
    </ItemTemplate>
    </asp:TemplateField>
    <asp:TemplateField HeaderText="地址">
    <ItemTemplate>
    <%# ((visitor)Container.DataItem).Vadd %>
    </ItemTemplate>
    </asp:TemplateField>
    </Columns>
    </asp:GridView>

后台代码
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data;
using System.Data.SqlClient;
using System.Collections;

public partial class _Default : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            this.GridView1.DataSource = bind();
            this.GridView1.DataBind();
        }
    }
    
    public List<visitor> bind()
    {
        List<visitor> lt = new List<visitor>();
       
        SqlConnection cn = new SqlConnection("server=.;database=pubs;uid=sa;pwd=sa");
        cn.Open();
        SqlCommand cmd = new SqlCommand("select stuid,stuname,stuadd from sj",cn);
        SqlDataReader dr = cmd.ExecuteReader();
        while (dr.Read())
        {   visitor vs = new visitor();
           vs.Vid= dr[0].ToString();
           vs.Vname = dr[1].ToString();
           vs.Vadd = dr[2].ToString();
           lt.Add(vs);
        }
       
        dr.Close();
        return lt;


    }
}
public class visitor
{
   public string Vname;
   public string Vid;
   public string Vadd;
}