把DATASET数据写入客户端EXCEL文件（利用DataTable）

 public void DatasetToExcel(DataSet ds, string fileName)
        {
            //DataSet ds = (DataSet)this.Cache["DataSet"];
            DataTable dt = ds.Tables[0];

            System.IO.StringWriter sw = new System.IO.StringWriter();
            sw.WriteLine("ID\t类型ID\t姓名");
            foreach (DataRow dr in dt.Rows)
            {
                sw.WriteLine(dr["id"] + "\t" + dr["typeId"] + "\t" + dr["typeName"]);
            }
            sw.Close();
            Response.AddHeader("Content-Disposition", "attachment; filename=" + System.Web.HttpUtility.UrlEncode(fileName, System.Text.Encoding.UTF8) + ".xls");
            Response.ContentType = "application/ms-excel";
            Response.ContentEncoding = System.Text.Encoding.GetEncoding("GB2312");
            Response.Write(sw);
            Response.End();
        }

要注意的是fileName 必须进行转换，不然下载的文件名是乱码。