C# 将datatable导出成Excel

public void result( )
{

try
{
stringbuilder sql = new stringbuilder();
list<sqlparameter> parameters = new list<sqlparameter>();

sql.append(@"sql 查询语句");
datatable dt = dbhelpersql.query(sql.tostring()).tables[0];
stringbuilder tablehead = new stringbuilder();
stringbuilder tablefoot = new stringbuilder();
tablehead.append("<tr style=\"font-weight: bold; white-space: nowrap;\">")
.append("<td rowspan =\"2\"></td></tr>")
.append("<tr></tr>");
tablefoot.append("<tr><td colspan = \"4\">导出时间：" + datetime.now.tostring("yyyy年mm月dd日 hh:mm:ss") + "</td></tr>");
datatabletoexcel(dt, tablehead.tostring(), tablefoot.tostring(), name + "汇总_" + datetime.now.tostring("yyyymm"));

}
catch (exception ex)
{

}
}

/// <summary>
/// datatable导出excel
/// </summary>
/// <param name="data">集合</param>
/// <param name="charthead">表头</param>
/// <param name="filename">文件名称</param>
public static void datatabletoexcel(datatable data, string charthead, string chartfoot, string filename)
{
httpcontext.current.response.contenttype = "application/vnd.ms-excel";
httpcontext.current.response.contentencoding = encoding.utf8;
httpcontext.current.response.charset = "utf-8";
httpcontext.current.response.appendheader("content-disposition", "attachment;filename=" + httputility.urlencode(filename + ".xls", encoding.utf8));
stringbuilder sbhtml = new stringbuilder();
sbhtml.appendline("<meta http-equiv=\"content-type\" content=\"text/html; charset=utf-8\">");
sbhtml.appendline("<table cellspacing=\"0\" cellpadding=\"5\" rules=\"all\" border=\"1\">");
//写出表头
sbhtml.appendline(charthead);
string numberastextexp = "vnd.ms-excel.numberformat:@";
//写数据
foreach (datarow row in data.rows)
{
sbhtml.append("<tr>");
for (int i = 0; i < row.itemarray.count(); i++)
{
if (row[i].gettype() == typeof(string))
{
sbhtml.append("<td style='" + numberastextexp + "'>").append(row[i]).append("</td>");
}
else
{
sbhtml.append("<td>").append(row[i]).append("</td>");
}
}
sbhtml.appendline("</tr>");
}
//写汇总行
sbhtml.appendline(chartfoot);
sbhtml.appendline("</table>");
httpcontext.current.response.write(sbhtml.tostring());
httpcontext.current.response.end();
}