excel导出 按dataset里的datatable导出一个excel多个sheet 和 datatable导出

public static void DataSetToExcel(string filename, DataSet ds)
        {
            IWorkbook workbook = new HSSFWorkbook();
            for (int i = 0; i < ds.Tables.Count; i++)
            {
                string sheetName = ds.Tables[i].TableName;
                //增加序号列
                //rui.dbHelper.insert序号(table, 0);


                ISheet sheet = workbook.CreateSheet(sheetName);
                //设置单元格的样式：水平垂直居中
                ICellStyle style = workbook.CreateCellStyle();
                style.Alignment = HorizontalAlignment.Center;
                style.VerticalAlignment = VerticalAlignment.Center;
                //写标题
                IRow header = sheet.CreateRow(0);
                for (int j = 0; j < ds.Tables[i].Columns.Count; j++)
                {
                    ICell cell = header.CreateCell(j);
                    string value = ds.Tables[i].Columns[j].ColumnName;//标题转换
                    cell.SetCellValue(value);
                    cell.CellStyle = style;
                    //sheet.SetColumnWidth(i, 30 * 240);
                    //header.CreateCell(i).SetCellValue(table.Columns[i].ColumnName);
                }
                //写数据
                for (int j = 0; j < ds.Tables[i].Rows.Count; j++)
                {
                    IRow row = sheet.CreateRow(j + 1);//
                    for (int k = 0; k < ds.Tables[i].Columns.Count; k++)
                    {
                        string celltext = ds.Tables[i].Rows[i][k].ToString();
                        ICell cell = row.CreateCell(k);
                        cell.SetCellValue(celltext);
                        cell.CellStyle = style;

                    }
                }
                //宽度自适应
                for (int columnNum = 0; columnNum < ds.Tables[i].Columns.Count; columnNum++)
                {
                    int columnWidth = sheet.GetColumnWidth(columnNum) / 256;//获取当前列宽度  
                    for (int rowNum = 0; rowNum <= sheet.LastRowNum; rowNum++)//在这一列上循环行  
                    {
                        IRow currentRow = sheet.GetRow(rowNum);
                        ICell currentCell = currentRow.GetCell(columnNum);
                        int length = Encoding.UTF8.GetBytes(currentCell.ToString()).Length;//获取当前单元格的内容宽度  
                        if (columnWidth < length + 1)
                        {
                            columnWidth = length + 1;
                        }//若当前单元格内容宽度大于列宽，则调整列宽为当前单元格宽度，后面的+1是我人为的将宽度增加一个字符  
                    }
                    sheet.SetColumnWidth(columnNum, columnWidth * 256);
                }

            }
            // 写入到客户端  
            System.IO.MemoryStream ms = new System.IO.MemoryStream();
            workbook.Write(ms);
            HttpContext.Current.Response.ContentType = "application/vnd.ms-excel";
            HttpContext.Current.Response.Charset = "UTF8";
            //根据不同的浏览器设置对应的文件名
            string attachFilename = "";
            {
                string enCodeFilename = HttpUtility.UrlEncode(filename, System.Text.Encoding.UTF8);
                string userAgent = HttpContext.Current.Request.Browser.Browser;
                userAgent = userAgent.ToLower();

                //rui.logTools.log("浏览器类型：" + userAgent);

                //IE浏览器
                if (userAgent.IndexOf("ie") != -1 || userAgent.IndexOf("mozilla") != -1)
                {
                    attachFilename = @"filename=" + enCodeFilename;
                }
                //Opera浏览器只能采用filename* 
                else if (userAgent.IndexOf("opera") != -1)
                {
                    attachFilename = @"filename*=UTF-8‘‘" + enCodeFilename;
                }
                //FireFox浏览器
                else if (userAgent.IndexOf("firefox") != -1)
                {
                    attachFilename = @"filename*=" + enCodeFilename;
                }
                //遨游
                else if (userAgent.IndexOf("chrome") != -1)
                {
                    attachFilename = @"filename=" + enCodeFilename;
                }
                else
                {
                    attachFilename = @"filename=" + enCodeFilename;
                }
            }
            HttpContext.Current.Response.AddHeader("Content-Disposition",
                string.Format("attachment;{0}.xls", attachFilename));

            HttpContext.Current.Response.BinaryWrite(ms.ToArray());
            HttpContext.Current.Response.End();
            workbook = null;
            ms.Close();
            ms.Dispose();


        }