更改HtmlTextWriter创建的thead标签

Question

我正在使用C＃的HtmlTextWriter创建一个HTML表格 当我循环创建我的表头时，它会以这种格式创建它

<tr><th>colname</th><th>colname</th><th>colname</th><th>colname</th></tr>

我希望<tr>说<thead>而<th>说<td>。

如何编程HtmlTextWriter来更改标记值？

这是我创建标题的循环。

public void BuildHTMLTable(DataTable dt)
{
    StringWriter sw = new StringWriter();
    HtmlTextWriter w = new HtmlTextWriter(sw);

    Table tbl = new Table();
    tbl.ID = "example";
    tbl.CssClass = "display";
    tbl.CellSpacing = 0;

    TableHeaderRow thr = new TableHeaderRow();
    foreach (DataColumn col in dt.Columns)
    {
        TableCell th = new TableCell();
        th.Text = col.Caption;
        thr.Controls.Add(th);
    }
    tbl.Controls.Add(thr);

    foreach (DataRow row in dt.Rows)
    {
        TableRow tr = new TableRow();
        foreach (var value in row.ItemArray)
        {
            TableCell td = new TableCell();
            td.Text = value.ToString();
            tr.Controls.Add(td);
        }
        tbl.Controls.Add(tr);
    }

    TableFooterRow tfr = new TableFooterRow();
    foreach (DataColumn col in dt.Columns)
    {
        TableCell th = new TableCell();
        th.Text = col.Caption;
        tfr.Controls.Add(th);
    }
    tbl.Controls.Add(tfr);
    tbl.RenderControl(w);
    tableString = sw.ToString();
}