gridview导出csv的问题

[HaiYang2006]

GridView1.DataSource = myDataSet;
GridView1.DataBind();

GridView1.AllowPaging = false;
GridView1.AllowSorting = false;
/////////////////////////////////////////////////////////
Response.Clear();
Response.Buffer = true;
Response.ContentEncoding = Encoding.GetEncoding("gb2312");
Response.Charset = "";
Response.AddHeader("Content-Disposition", "attachment; filename=" + System.Web.HttpUtility.UrlEncode(filename.Replace(" ", "") + ".csv", System.Text.Encoding.UTF8));
Response.ContentType = "text/txt";

StringBuilder sb = new StringBuilder();

Page page = new Page();
HtmlForm form = new HtmlForm();

GridView1.EnableViewState = false;
// Deshabilitar la validación de eventos, sólo asp.net 2
page.EnableEventValidation = false;
// Realiza las inicializaciones de la instancia de la clase Page que requieran los diseñadores RAD.
page.DesignerInitialize();

page.Controls.Add(form);
form.Controls.Add(GridView1);

StringWriter sw = new StringWriter(sb);

try
{
//SaveFileDialog sfd = new SaveFileDialog();//myGridView.Columns[2].HeaderText, myGridView.Columns[3].HeaderText,//品牌, 产品名称,导出时不给外呼公司看到
sw.WriteLine(string.Format("{0}, {1}, {2}, {3}, {4}, {5}", GridView1.Columns[0].HeaderText, "ID", GridView1.Columns[1].HeaderText, GridView1.Columns[2].HeaderText, GridView1.Columns[3].HeaderText, GridView1.Columns[4].HeaderText));

int i = 1;
foreach (DataRow dr in myDataSet.Tables[0].Rows)
{
sw.WriteLine(string.Format("{0}, {1}, {2}, {3}, {4}, {5}", i, dr["oident"].ToString(), dr["number"].ToString(), dr["t_ident"].ToString(), dr["fDate"].ToString(), dr["cName"].ToString()));
i++;
}
}
catch (Exception ex)
{
ex.Message.ToString();
}
finally
{
sw.Close();
sw.Dispose();
}

Response.Write(sb);
Response.End();---------用此方法csv里没有乱码，但有异常：由于代码已经过优化或者本机框架位于调用堆栈之上,无法计算表达式的值
//System.Web.HttpContext.Current.ApplicationInstance.CompleteRequest();----------用此方法csv里有乱码，如：
" <table cellspacing=""0"" cellpadding=""1"" rules=""all"" border=""1"" id=""GridView1"" style=""border-color:#E3F0FF;border-width:1px;border-style:solid;width:738px;border-collapse:collapse;word-break:break-all;word-wrap:break-word"">"。。。。。。。

有好的解决方法吗？

[flyfly2008]

UP

[HaiYang2006]

uppp

[flyerwing]

Response.ContentEncoding = Encoding.GetEncoding("gb2312");
System.Text.Encoding.UTF8));
UP