导出到csv文件

用下面这个方法可以从sqlserver数据库导出大量的数据到csv文件.
但是在导出文件的时候,为什么点击网站上的其它链接无响应呢?要等到整个文件下载完才有响应?public void ExportToExcel(SqlDataSource dataSrc, string fileName)
{
    //Add Response header     Response.Clear();
    Response.AddHeader("content-disposition", 
        string.Format("attachment;filename={0}.csv", fileName));
    Response.Charset = "";
    Response.ContentType = "application/vnd.xls";
    //GET Data From Database                    SqlConnection cn = new SqlConnection(dataSrc.ConnectionString);
    string query = 
        dataSrc.SelectCommand.Replace("\r\n", " ").Replace("\t", " ");
        
    SqlCommand cmd = new SqlCommand(query, cn);
        
    cmd.CommandTimeout = 999999 ;
    cmd.CommandType    = CommandType.Text;
    try
    {
        cn.Open();
        SqlDataReader dr = cmd.ExecuteReader();
        StringBuilder sb = new StringBuilder();            
        //Add Header                  for (int count = 0; count < dr.FieldCount; count++)
        {
            if (dr.GetName(count) != null)
                sb.Append(dr.GetName(count));
            if (count < dr.FieldCount - 1)
            {
                sb.Append(",");
            }
        }
        Response.Write(sb.ToString() + "\n");
        Response.Flush();            
        //Append Data        while (dr.Read())
        {
            sb = new StringBuilder();
               
            for (int col = 0; col < dr.FieldCount - 1; col++)
            {
                if (!dr.IsDBNull(col))
                    sb.Append(dr.GetValue(col).ToString().Replace(",", " "));
                    sb.Append(",");
            }
            if (!dr.IsDBNull(dr.FieldCount - 1))
                sb.Append(dr.GetValue(
                dr.FieldCount - 1).ToString().Replace(",", " "));
            Response.Write(sb.ToString() + "\n");
            Response.Flush();
        }
        dr.Dispose();
    }
    catch (Exception ex)
    {
        Response.Write(ex.Message);
    }
    finally
    {
        cmd.Connection.Close();
        cn.Close();
    }
    Response.End();
}