/// <summary>        /// 创建工作簿        /// </summary>        /// <param name="fileName">下载文件名</param>        /// <param name="dt">数据源</param>        public static void CreateSheet(string fileName, DataTable dt)        {            HSSFWorkbook workbook = new HSSFWorkbook();            MemoryStream ms = new MemoryStream();            //创建一个名称为Payment的工作表            ISheet paymentSheet = workbook.CreateSheet("Payment");            //数据源            DataTable tbPayment = dt;            //头部标题            IRow paymentHeaderRow = paymentSheet.CreateRow(0);            //循环添加标题            foreach (DataColumn column in tbPayment.Columns)                paymentHeaderRow.CreateCell(column.Ordinal).SetCellValue(column.ColumnName);            // 内容            int paymentRowIndex = 1;            foreach (DataRow row in tbPayment.Rows)            {                IRow newRow = paymentSheet.CreateRow(paymentRowIndex);                //循环添加列的对应内容                foreach (DataColumn column in tbPayment.Columns)                {                    newRow.CreateCell(column.Ordinal).SetCellValue(row[column].ToString());                }                paymentRowIndex++;            }            //列宽自适应，只对英文和数字有效            for (int i = 0; i <= dt.Rows.Count; i++)            {                paymentSheet.AutoSizeColumn(i);            }            //获取当前列的宽度，然后对比本列的长度，取最大值            for (int columnNum = 0; columnNum <= dt.Rows.Count; columnNum++)            {                int columnWidth = paymentSheet.GetColumnWidth(columnNum) / 256;                for (int rowNum = 1; rowNum <= paymentSheet.LastRowNum; rowNum++)                {                    IRow currentRow;                    //当前行未被使用过                    if (paymentSheet.GetRow(rowNum) == null)                    {                        currentRow = paymentSheet.CreateRow(rowNum);                    }                    else                    {                        currentRow = paymentSheet.GetRow(rowNum);                    }                    if (currentRow.GetCell(columnNum) != null)                    {                        ICell currentCell = currentRow.GetCell(columnNum);                        int length = Encoding.Default.GetBytes(currentCell.ToString()).Length;                        if (columnWidth < length)                        {                            columnWidth = length;                        }                    }                }                paymentSheet.SetColumnWidth(columnNum, columnWidth * 256);            }            //将表内容写入流 通知浏览器下载            workbook.Write(ms);            System.Web.HttpContext.Current.Response.AddHeader("Content-Disposition", string.Format("attachment; filename={0}.xls", fileName));            System.Web.HttpContext.Current.Response.BinaryWrite(ms.ToArray()); //进行二进制流下在            workbook = null;            ms.Close();            ms.Dispose();        }        /// <summary>        /// 虚拟 DataTable内容        /// </summary>        /// <returns></returns>        public static DataTable CreatTable()        {            //创建DataTable 将数据库中没有的数据放到这个DT中            DataTable datatable = new DataTable();            datatable.Columns.Add("列1", typeof(string));            datatable.Columns.Add("列2", typeof(string));            datatable.Columns.Add("列3", typeof(string));            //创建DatatTable 结束---------------------------            //开始给临时datatable赋值            for (int i = 0; i < 10; i++)            {                DataRow row = datatable.NewRow();                row["列1"] = "列111111111111111111111111111111";                row["列2"] = "列222222222222222222222222222222222222222";                row["列3"] = "列3333333322222222222211111111111111111111111113";                datatable.Rows.Add(row);            }            return datatable;        }