关于NPOIExcel导出excel

1.支持导出多个sheet文件

  /// <summary>
         ///  导出到Excel并下载（html）
         /// </summary>
         /// <param name="tablels">需要导出的Excel表集合</param>
         public static void ToExcel(List<DataTable> tablels, string fileName = "")
         {

             if (fileName == "")
             {
                 fileName = "数据导出汇总-" + DateTime.Now.ToString("yyyyMMddHHmmssfff") + ".xls"; // 文件名称
             }
             string urlPath = "UpFiles/ExcelFiles/" + fileName; // 文件下载的URL地址，供给前台下载

             string filePath = HttpContext.Current.Server.MapPath("\\" + urlPath); // 文件路径

             string directoryName = Path.GetDirectoryName(filePath);

             if (!Directory.Exists(directoryName))
             {
                 Directory.CreateDirectory(directoryName);
             }
             IWorkbook workBook = new HSSFWorkbook();

             foreach (DataTable table in tablels)
             {

                 string sheetName = table.TableName;
                 FileStream fs = new FileStream(filePath, FileMode.OpenOrCreate, FileAccess.ReadWrite);
                 sheetName = string.IsNullOrEmpty(sheetName) ? "sheet1" : sheetName;
                 ISheet sheet = workBook.CreateSheet(sheetName);

                 //处理表格标题
                 IRow row = sheet.CreateRow();
                 row.CreateCell().SetCellValue(sheetName);
                 sheet.AddMergedRegion(new CellRangeAddress(, , , table.Columns.Count - ));
                 row.Height = ;

                 ICellStyle cellStyle = workBook.CreateCellStyle();
                 IFont font = workBook.CreateFont();
                 font.FontName = "微软雅黑";
                 font.FontHeightInPoints = ;
                 cellStyle.SetFont(font);
                 cellStyle.VerticalAlignment = VerticalAlignment.Center;
                 cellStyle.Alignment = HorizontalAlignment.Center;
                 row.Cells[].CellStyle = cellStyle;

                 //处理表格列头
                 row = sheet.CreateRow();
                 for (int i = ; i < table.Columns.Count; i++)
                 {
                     row.CreateCell(i).SetCellValue(table.Columns[i].ColumnName);
                     row.Height = ;
                     sheet.AutoSizeColumn(i);
                 }

                 //处理数据内容
                 for (int i = ; i < table.Rows.Count; i++)
                 {
                     row = sheet.CreateRow( + i);
                     row.Height = ;
                     for (int j = ; j < table.Columns.Count; j++)
                     {
                         row.CreateCell(j).SetCellValue(table.Rows[i][j].ToString());
                         sheet.SetColumnWidth(j,  * );
                     }
                 }
                 //写入数据流
                 workBook.Write(fs);
                 fs.Flush();
                 fs.Close();
             }
             // 3.进行Excel转换操作，并返回转换的文件下载链接
             System.Web.Script.Serialization.JavaScriptSerializer js = new System.Web.Script.Serialization.JavaScriptSerializer();
             HttpContext.Current.Response.ContentType = "text/plain";
             HttpContext.Current.Response.Write(js.Serialize(urlPath)); // 返回Json格式的内容
         }

2.只支持一个sheet文件

  /// <summary>
         ///  导出到Excel并下载（html）
        /// </summary>
        /// <param name="table">数据源</param>
        /// <param name="title">标题</param>
        /// <param name="sheetName">sheetName名称</param>
        /// <param name="fileName">路径</param>
         public static void ToExcel(DataTable table, string title, string sheetName, string fileName = "")
         {
             if (fileName == "")
             {
                 fileName = sheetName + "-" + DateTime.Now.ToString("yyyyMMddHHmmssfff") + ".xls"; // 文件名称
             }
             string urlPath = "UpFiles/ExcelFiles/" + fileName; // 文件下载的URL地址，供给前台下载

             string filePath = HttpContext.Current.Server.MapPath("\\" + urlPath); // 文件路径

             string directoryName = Path.GetDirectoryName(filePath);

             if (!Directory.Exists(directoryName))
             {
                 Directory.CreateDirectory(directoryName);
             }

             FileStream fs = new FileStream(filePath, FileMode.OpenOrCreate, FileAccess.ReadWrite);
             IWorkbook workBook = new HSSFWorkbook();
             sheetName = string.IsNullOrEmpty(sheetName) ? "sheet1" : sheetName;
             ISheet sheet = workBook.CreateSheet(sheetName);

             //处理表格标题
             IRow row = sheet.CreateRow();
             row.CreateCell().SetCellValue(title);
             sheet.AddMergedRegion(new CellRangeAddress(, , , table.Columns.Count - ));
             row.Height = ;

             ICellStyle cellStyle = workBook.CreateCellStyle();
             IFont font = workBook.CreateFont();
             font.FontName = "微软雅黑";
             font.FontHeightInPoints = ;
             cellStyle.SetFont(font);
             cellStyle.VerticalAlignment = VerticalAlignment.Center;
             cellStyle.Alignment = HorizontalAlignment.Center;
             row.Cells[].CellStyle = cellStyle;

             //处理表格列头
             row = sheet.CreateRow();
             for (int i = ; i < table.Columns.Count; i++)
             {
                 row.CreateCell(i).SetCellValue(table.Columns[i].ColumnName);
                 row.Height = ;
                 sheet.AutoSizeColumn(i);
             }

             //处理数据内容
             for (int i = ; i < table.Rows.Count; i++)
             {
                 row = sheet.CreateRow( + i);
                 row.Height = ;
                 for (int j = ; j < table.Columns.Count; j++)
                 {
                     row.CreateCell(j).SetCellValue(table.Rows[i][j].ToString());
                     sheet.SetColumnWidth(j,  * );
                 }
             }

             //写入数据流
             workBook.Write(fs);
             fs.Flush();
             fs.Close();

             // 3.进行Excel转换操作，并返回转换的文件下载链接
             System.Web.Script.Serialization.JavaScriptSerializer js = new System.Web.Script.Serialization.JavaScriptSerializer();
             HttpContext.Current.Response.ContentType = "text/plain";
             HttpContext.Current.Response.Write(js.Serialize(urlPath)); // 返回Json格式的内容
         }