把数据库里的数据用Excel文件的格式显示在浏览器中

页面的载入事件：
 private void Page_Load(object sender, System.EventArgs e)
  {
   DataSet objDataset = new DataSet();
   SqlConnection objConn = new SqlConnection();
   objConn = new SqlConnection(ConfigurationSettings.AppSettings["ConnectionSqlServer"].ToString());
   objConn.Open();
   SqlDataAdapter objAdapter = new SqlDataAdapter("Select top 5 * from customers where country='USA'",objConn);
   objAdapter.Fill(objDataset); 
   DataView oView = new DataView(objDataset.Tables[0]);
   dgExcel.DataSource = oView;
   dgExcel.DataBind();
   objConn.Close();
   objConn.Dispose();
   objConn = null;
   if(Request.QueryString["bExcel"] == "1")
   {
    Response.ContentType = "application/vnd.ms-excel";
    
    Response.Charset = "";

    //关闭 ViewState
    EnableViewState = false;
    System.IO.StringWriter tw = new System.IO.StringWriter();//将信息写入字符串
    System.Web.UI.HtmlTextWriter hw = new System.Web.UI.HtmlTextWriter(tw);//在WEB窗体页上写出一系列连续的HTML特定字符和文本。
    //此类提供ASP.NET服务器控件在将HTML内容呈现给客户端时所使用的格式化功能
    //获取control的HTML
    dgExcel.RenderControl(hw);//将DATAGRID中的内容输出到HtmlTextWriter对象中
    // 把HTML写回浏览器
    Response.Write(tw.ToString());
    Response.End();
   }

在页面上按Button，触发Button_Click 事件，实现功能
private void btnGetExcel_Click(object sender, System.EventArgs e)
  {
   Response.Redirect("excel.aspx?bExcel=1");
  }