asp.net Repeater显示父子表数据,无闪烁

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; 

namespace RepeaterTest 
{ 
public partial class Repeater : System.Web.UI.Page 
{ 
protected void Page_Load(object sender, EventArgs e) 
{ 
if (!Page.IsPostBack) 
{ 
this.bind(); 
} 
} 

private DataSet dataSource 
{ 
get 
{ 
if (ViewState["ds"] != null) 
{ 
return (DataSet)ViewState["ds"]; 
} 
else 
{ 
DataSet ds = DataSource.GetDataSet(); 
ViewState["ds"] = ds; 
return ds; 
} 
} 
} 

private void bind() 
{ 
DataSet ds = this.dataSource; 

this.Repeater1.DataSource = ds.Tables["tbclass"]; 
this.Repeater1.DataBind(); 

this.Repeater2.DataSource = ds.Tables["tbclass"]; 
this.Repeater2.DataBind(); 
} 

protected void Repeater1_ItemCommand(object source, RepeaterCommandEventArgs e) 
{ 
if (e.CommandName == "expand") 
{ 
LinkButton btn = (LinkButton)e.CommandSource; 
GridView grid =(GridView)btn.Parent.FindControl("grid1"); 
if (btn.Text == "+") 
{ 
btn.Text = "-"; 
grid.Visible = true; 
} 
else 
{ 
btn.Text = "+"; 
grid.Visible = false; 
} 
} 
} 

protected void Repeater1_ItemDataBound(object sender, RepeaterItemEventArgs e) 
{ 
DataTable dt = this.dataSource.Tables["tbstu"]; 
LinkButton objButton = (LinkButton)e.Item.FindControl("btnExpand"); 
if (objButton != null && objButton.CommandArgument !="") 
{ 
string classID = objButton.CommandArgument; 
dt.DefaultView.RowFilter = "ClassID=" + classID; 
DataTable dtStu = dt.DefaultView.ToTable(); 

GridView grid = (GridView)e.Item.FindControl("grid1"); 
grid.DataSource = dtStu; 
grid.DataBind(); 
} 
} 

protected void Repeater2_ItemDataBound(object sender, RepeaterItemEventArgs e) 
{ 
DataTable dt = this.dataSource.Tables["tbstu"]; 
Label objlbl = (Label)e.Item.FindControl("lblclassid"); 
if (objlbl != null && objlbl.Text != "") 
{ 
string classID = objlbl.Text; 
dt.DefaultView.RowFilter = "ClassID=" + classID; 
DataTable dtStu = dt.DefaultView.ToTable(); 

GridView grid = (GridView)e.Item.FindControl("grid2"); 
grid.DataSource = dtStu; 
grid.DataBind(); 
} 
} 
} 
}