public class ExcelController : Controller
    {
        //
        // GET: /Excel/
        Models.zbwxglEntities myMdl = new Models.zbwxglEntities();
        /// <summary>
        /// 第一種方法,利用文件輸出流進行讀寫操作
        /// </summary>
        public void outExcel()
        {
            DataTable dtData = (DataTable)Session["
 
datatable"];
            string shtnl = "";
            shtnl = "<table border=‘1‘ cellspacing=‘1‘ cellpadding=‘1‘>";
            shtnl = shtnl + "<thead>";
            for (int j = 0; j < dtData.Columns.Count; j++)
            {
                shtnl = shtnl + "<th>" + j + "</th>
 
";
            }
            shtnl = shtnl + "</thead><tbody>";
            for (int i = 0; i < dtData.Rows.Count; i++)
            {
                shtnl = shtnl + "<tr>";
                for (int j = 0; j < dtData.Columns.Count; j++)
                {
                        shtnl 
 
= shtnl + "<td>" + dtData.Rows[i][j] + "</td>";
                }
                shtnl = shtnl + "</tr>";
            }
            shtnl = shtnl + "</tbody></table>";
            ExportToExcel("application/x-excel", "123.xls", shtnl);
        }
        public void ExportToExcel(string FieldType, string FileName, string dt)
        {
            System.Web.HttpContext.Current.Response.Charset = "utf-8";
            System.Web.HttpContext.Current.Response.AppendHeader("Content-Disposition", "attachment;filename=" + HttpUtility.UrlEncode(FileName, System.Text.Encoding.UTF8).ToString());
            System.Web.HttpContext.Current.Response.ContentEncoding = System.Text.Encoding.GetEncoding("GB2312");
            System.Web.HttpContext.Current.Response.ContentType = FieldType;
            StringWriter tw = new StringWriter();
            System.Web.HttpContext.Current.Response.Output.Write(dt);
            System.Web.HttpContext.Current.Response.Flush();
            System.Web.HttpContext.Current.Response.End();
        }
        /// <summary>
        /// 第二種方法，利用微軟自帶插件
        /// </summary>
        /// <returns></returns>
        public ActionResult DownloadFile()
        {
            try
            {
                DataTable dt = (DataTable)Session["datatable"];
                string strdate = DateTime.Now.ToString("yyyyMMddhhmmss");
                string str = Server.HtmlEncode(Request.PhysicalApplicationPath).ToString() + "Content\\DownLoadTest\\" + Session["YongHuID"] + strdate + "Excel.xls";
                if (System.IO.File.Exists(str))
                {
                    //如果存在則刪除
                    System.IO.File.Delete(str);
                }
                ConvertHelper myConvertHelper = new ConvertHelper();
                DataTableToExcel(dt, str);
                System.Threading.Thread.Sleep(5000);
                return File(str, "application/vnd.ms-excel", strdate + "Excel.xls");
            }
            catch
            {
                DataTable dt = new DataTable();
                List<Dictionary<string, object>> ListReturn = ConvertHelper.DtToList(dt);
                return Json(ListReturn, JsonRequestBehavior.AllowGet);
            }
        }
        public void DataTableToExcel(DataTable datas, string p)
        {

            Microsoft.Office.Interop.Excel.Application app = new Microsoft.Office.Interop.Excel.Application();
            app.SheetsInNewWorkbook = 1;
            app.Workbooks.Add();
            Microsoft.Office.Interop.Excel.Worksheet sheet = (Microsoft.Office.Interop.Excel.Worksheet)app.ActiveWorkbook.Worksheets[1];

            for (int i = 0; i < datas.Columns.Count; i++)
            {
                sheet.Cells[1, i + 1] = datas.Columns[i].ColumnName;
            }

            for (int i = 0; i < datas.Rows.Count; i++)
            {
                for (int j = 0; j < datas.Columns.Count; j++)
                {
                    sheet.Cells[2 + i, j + 1] = datas.Rows[i][j].ToString();
                }
            }

            app.Visible = true;
            System.Threading.Thread.Sleep(500);
            try
            {
                app.ActiveWorkbook.SaveAs(p);
            }
            catch { }
            app.Quit();
        }
        /// <summary>
        /// 第三種方法，利用NPOI插件
        /// </summary>
        /// <returns></returns>
        public FileResult DownLoadExcelJiZuChaXunGenRenXiaoFeiJiLu()
        {
            DataTable dt = (DataTable)Session["datatable"];//獲取需要導出的datatable數據
            //創建Excel文件的對象
            NPOI.HSSF.UserModel.HSSFWorkbook book = new NPOI.HSSF.UserModel.HSSFWorkbook();
            //添加一個sheet
            NPOI.SS.UserModel.ISheet sheet1 = book.CreateSheet("Sheet1");
            //給sheet1添加第一行的頭部標題
            NPOI.SS.UserModel.IRow row1 = sheet1.CreateRow(0);
            //row1.RowStyle.FillBackgroundColor = "";
            for (int i = 0; i < dt.Columns.Count; i++)
            {
                row1.CreateCell(i).SetCellValue(dt.Columns[i].ColumnName);
            }
            //將數據逐步寫入sheet1各個行
            for (int i = 0; i < dt.Rows.Count; i++)
            {
                NPOI.SS.UserModel.IRow rowtemp = sheet1.CreateRow(i + 1);
                for (int j = 0; j < dt.Columns.Count; j++)
                {
                    rowtemp.CreateCell(j).SetCellValue(dt.Rows[i][j].ToString().Trim());
                }
            }
            string strdate = DateTime.Now.ToString("yyyyMMddhhmmss");//獲取當前時間
            // 寫入到客戶端 
            System.IO.MemoryStream ms = new System.IO.MemoryStream();
            book.Write(ms);
            ms.Seek(0, SeekOrigin.Begin);
            return File(ms, "application/vnd.ms-excel", strdate + "Excel.xls");
        }
        /// <summary>
        /// Excel導入
        /// </summary>
        /// <returns></returns>
        public ActionResult GetTableFromExcel()
        {
            //FileStream file = new FileStream(Server.HtmlEncode(Request.PhysicalApplicationPath).ToString() + "excel\\123.xlsx", FileMode.Open, FileAccess.Read);

            HttpPostedFileBase fostFile = Request.Files["file1"];
            Stream streamfile = fostFile.InputStream;
            //HSSFWorkbook hssfworkbook = new HSSFWorkbook(streamfile);
            HSSFWorkbook hssfworkbook = new HSSFWorkbook(streamfile);
            using (NPOI.SS.UserModel.ISheet sheet = hssfworkbook.GetSheetAt(0))
            {
                DataTable table = new DataTable();
                IRow headerRow = sheet.GetRow(0);//第一行為標題行
                int cellCount = headerRow.LastCellNum;//LastCellNum = PhysicalNumberOfCells
                int rowCount = sheet.LastRowNum;//LastRowNum = PhysicalNumberOfRows - 1
                //handling header.
                for (int i = headerRow.FirstCellNum; i < cellCount; i++)
                {
                    DataColumn column = new DataColumn(headerRow.GetCell(i).StringCellValue);
                    table.Columns.Add(column);
                }
                for (int i = (sheet.FirstRowNum + 1); i <= rowCount; i++)
                {
                    IRow row = sheet.GetRow(i);
                    DataRow dataRow = table.NewRow();
                    if (row != null)
                    {
                        for (int j = row.FirstCellNum; j < cellCount; j++)
                        {
                            if (row.GetCell(j) != null)
                                dataRow[j] = GetCellValue(row.GetCell(j));
                        }
                    }
                    table.Rows.Add(dataRow);
                }
                for (int i = 0; i < table.Rows.Count; i++)
                {
                    //myUpLoadBLL.ForDownLoad(table.Rows[i][1].ToString(), table.Rows[i][2].ToString(),Convert.ToBoolean( table.Rows[i][3]));
                }
            }
            return Content("");
        }
        /// <summary>
        /// 根據Excel列類型獲取列的值
        /// </summary>
        /// <param name="cell">Excel列</param>
        /// <returns></returns>
        private static string GetCellValue(ICell cell)
        {
            if (cell == null)
                return string.Empty;
            switch (cell.CellType)
            {
                case CellType.BLANK:
                    return string.Empty;
                case CellType.BOOLEAN:
                    return cell.BooleanCellValue.ToString();
                case CellType.ERROR:
                    return cell.ErrorCellValue.ToString();
                case CellType.NUMERIC:
                case CellType.Unknown:
                default:
                    return cell.ToString();
                case CellType.STRING:
                    return cell.StringCellValue;
                case CellType.FORMULA:
                    try
                    {
                        HSSFFormulaEvaluator e = new HSSFFormulaEvaluator(cell.Sheet.Workbook);
                        e.EvaluateInCell(cell);
                        return cell.ToString();
                    }
                    catch
                    {
                        return cell.NumericCellValue.ToString();
                    }
            }
        }
    }

.Net MVC 導入導出Excel總結(三種導出Excel方法，一種導入Excel方法) 通過MVC控制器導出導入Excel文件(可用於java SSH架構)