public static MemoryStream ExportToExcel(DataSet ds,ExcelType excelType,string header)

        {

            IWorkbook workbook = null;

            if (excelType==ExcelType.Office2003)

            {

                workbook = new HSSFWorkbook();//2003

            }

            else

            {

                workbook = new XSSFWorkbook();//2007

            }



            #region 开始循环DS中的Table,DS中的每个表创建一个Sheet

            for (int p = 0; p < ds.Tables.Count; p++)

            {

                #region 创建一个sheet

                ISheet sheet = workbook.CreateSheet("sheet" + (p + 1));

                //设置大标题行   

                int rowCount = 0;





                //设置全局列宽和行高   

                sheet.DefaultColumnWidth = 14; //全局列宽   

                sheet.DefaultRowHeightInPoints = 15; //全局行高   

                //设置标题行数据   

                int a = 0;

                



                IRow row1 = sheet.CreateRow(rowCount); //创建报表表头标题列   

                //for (int k = 0; k < ds.Tables[p].Columns.Count; k++)

                //{ //将DataTable的列标题输出到Excel

                //    columnName = ds.Tables[p].Columns[k].ColumnName;

                //    row1.CreateCell(a).SetCellValue(columnName);

                //    a++;

                //}

                

                string[] columnHeaders = header.Split(new char[] {','});//按逗号拆分标题

                var style = SetCellBorder(workbook);



                for (int k = 0; k <columnHeaders.Length; k++)

                {  //将传递过来的字符串表头进行拆分到Excel

                    

                    string columnName = columnHeaders[k];

                    ICell cell=row1.CreateCell(a);

                    cell.SetCellValue(columnName);



                    #region 设置单元格的边框

                    cell.CellStyle = style;

                    #endregion

                    a++;

                }



                //填写ds数据进excel   

                for (int i = 0; i < ds.Tables[p].Rows.Count; i++) //写行数据   

                {

                    IRow row2 = sheet.CreateRow(i + rowCount + 1);

                    int b = 0;

                    for (int j = 0; j < ds.Tables[p].Columns.Count; j++)

                    {

                        string dgvValue = string.Empty;

                        dgvValue = ds.Tables[p].Rows[i][j].ToString();

                        ICell cell = row2.CreateCell(b);

                        cell.SetCellValue(dgvValue);



                        #region 设置单元格的边框

                        cell.CellStyle = style;

                        #endregion

                        b++;

                    }

                }



                #endregion

            }

            #endregion



            //创建excel   

            MemoryStream memoryStream = new MemoryStream();

            workbook.Write(memoryStream);

            memoryStream.Seek(0, SeekOrigin.Begin);

            return memoryStream;

        }

            string header = "编号,用户名,姓名,角色";

            MemoryStream ms =ExcelHelper.ExportToExcel(ds, ExcelType.Office2003, header);

            return File(ms, "application/vnd.ms-excel", "用户信息");