public void CreateExcel(DataTable dt, string fileName)
{

HttpResponse resp = System.Web.HttpContext.Current.Response;
resp.ContentEncoding = System.Text.Encoding.GetEncoding("GB2312");
resp.AppendHeader("Content-Disposition", "attachment;filename=" + fileName);
string colHeaders = "", ls_item = "";
////定义表对象与行对象，同时用DataSet对其值进行初始化
//DataTable dt = ds.Tables[0];
DataRow[] myRow = dt.Select();//可以类似dt.Select("id>10")之形式达到数据筛选目的
int i = 0;
int cl = dt.Columns.Count;
//取得数据表各列标题，各标题之间以t分割，最后一个列标题后加回车符
for (i = 0; i < cl; i++)
{
if (i == (cl - 1))//最后一列，加n
{
colHeaders += dt.Columns[i].Caption.ToString() + "\n";
}
else
{
colHeaders += dt.Columns[i].Caption.ToString() + "\t";
}
}
resp.Write(colHeaders);
//向HTTP输出流中写入取得的数据信息
//逐行处理数据
foreach (DataRow row in myRow)
{
//当前行数据写入HTTP输出流，并且置空ls_item以便下行数据
for (i = 0; i < cl; i++)
{
if (i == (cl - 1))//最后一列，加n
{
ls_item += row[i].ToString() + "\n";
}
else
{
ls_item += row[i].ToString() + "\t";
}
}
resp.Write(ls_item);
ls_item = "";
}
resp.End();

}