使用 NPOI 插件

//不带样式
public static string ToExcle(List<DataTable> datas, string fileName = "report", string exportpath = "", int from = 1)
        {
            //获取文件物理路径
            string xlsPath = Path.Combine(Environment.CurrentDirectory, exportpath, fileName);
            //判断路径，不存在则创建
            if (!Directory.Exists(Path.Combine(Environment.CurrentDirectory, exportpath)))                                //存在则删除
            {
                Directory.CreateDirectory(Path.Combine(Environment.CurrentDirectory, exportpath));
            }

            FileStream file = new FileStream(xlsPath, FileMode.OpenOrCreate, FileAccess.ReadWrite);
            //获取文件虚拟路径
            string saveFileName = Path.Combine(exportpath, fileName);
            //创建文件
            StreamWriter objStreamWriter = new StreamWriter(file, Encoding.Unicode);
            IWorkbook hssfworkbook = new XSSFWorkbook();
            //遍历Excel标签
            var n = 0;
            foreach (DataTable data in datas)
            {
                if (data.Rows.Count > 0)
                {
                    if (string.IsNullOrEmpty(data.TableName))
                        data.TableName = "Sheet1";
                    //标签页名称
                    ISheet sheet = hssfworkbook.CreateSheet(data.TableName);
                    n++;
                    //标题行  
                    XSSFRow dataRow = sheet.CreateRow(0) as XSSFRow;
                    for (int i = 0; i < data.Columns.Count; i++)
                    {
                        if (!string.IsNullOrWhiteSpace(data.Columns[i].ColumnName))
                        {
                            dataRow.CreateCell(i).SetCellValue(data.Columns[i].ColumnName); //列值
                        }
                    }
                    //内容行
                    for (int i = 0; i < data.Rows.Count; i++)
                    {
                        dataRow = sheet.CreateRow(i + from) as XSSFRow;
                        for (int j = 0; j < data.Columns.Count; j++)
                        {
                            Regex regex = new Regex(@"<(.|\n)+?>");
                            var result = regex.Replace(data.Rows[i][j].ToString(), "");
                            dataRow.CreateCell(j).SetCellValue(result); //列值
                        }
                    }
                    sheet.ForceFormulaRecalculation = true;
                    if (data.Columns.Contains("ID（勿删）"))
                        sheet.SetColumnHidden(0, true);
                    if (data.Columns.Contains("PID（勿删）"))
                        sheet.SetColumnHidden(1, true);
                }

            }
            //hssfworkbook.RemoveSheetAt(0);
            //file.Dispose();
            objStreamWriter.Dispose();
            using (FileStream fileWrite = new FileStream(xlsPath, FileMode.Create))
            {
                hssfworkbook.Write(fileWrite);
                fileWrite.Dispose();
            }
            return saveFileName;
        }

 

//带样式
  public static string ToStyleExcle(List<DataTable> datas, int type, string fileName = "report", string exportpath = "", int from = 1, int selection = 0, string usercode = "")
        {
            //获取文件物理路径
            string xlsPath = Path.Combine(Environment.CurrentDirectory, exportpath, fileName);
            //判断路径，不存在则创建
            if (!Directory.Exists(Path.Combine(Environment.CurrentDirectory, exportpath)))                                //存在则删除
            {
                Directory.CreateDirectory(Path.Combine(Environment.CurrentDirectory, exportpath));
            }

            FileStream file = new FileStream(xlsPath, FileMode.OpenOrCreate, FileAccess.ReadWrite);
            //获取文件虚拟路径
            string saveFileName = Path.Combine(exportpath, fileName);
            //创建文件
            StreamWriter objStreamWriter = new StreamWriter(file, Encoding.Unicode);
            IWorkbook hssfworkbook = new XSSFWorkbook();


            //遍历Excel标签
            var n = 0;
            foreach (DataTable data in datas)
            {
                if (data.Rows.Count > 0)
                {
                    //标签页名称
                    ISheet sheet = hssfworkbook.CreateSheet(data.TableName);
                    n++;
                    //背景


                    ICellStyle style = hssfworkbook.CreateCellStyle();

                    style.FillForegroundColor = NPOI.HSSF.Util.HSSFColor.Yellow.Index;
                    style.FillPattern = FillPattern.SolidForeground;
                    style.BorderBottom = BorderStyle.Thin;
                    style.BorderLeft = BorderStyle.Thin;
                    style.BorderRight = BorderStyle.Thin;
                    style.BorderTop = BorderStyle.Thin;
                    style.Alignment = HorizontalAlignment.Center;
                    style.VerticalAlignment = VerticalAlignment.Center;

                    ICellStyle style1 = hssfworkbook.CreateCellStyle();
                    style1.FillForegroundColor = NPOI.HSSF.Util.HSSFColor.Lime.Index;
                    style1.FillPattern = FillPattern.SolidForeground;
                    style1.BorderBottom = BorderStyle.Thin;
                    style1.BorderLeft = BorderStyle.Thin;
                    style1.BorderRight = BorderStyle.Thin;
                    style1.BorderTop = BorderStyle.Thin;
                    style1.Alignment = HorizontalAlignment.Center;
                    style1.VerticalAlignment = VerticalAlignment.Center;

                    ICellStyle style2 = hssfworkbook.CreateCellStyle();
                    style2.FillForegroundColor = NPOI.HSSF.Util.HSSFColor.Grey25Percent.Index;
                    style2.FillPattern = FillPattern.SolidForeground;
                    style2.BorderBottom = BorderStyle.Thin;
                    style2.BorderLeft = BorderStyle.Thin;
                    style2.BorderRight = BorderStyle.Thin;
                    style2.BorderTop = BorderStyle.Thin;
                    style2.Alignment = HorizontalAlignment.Center;
                    style2.VerticalAlignment = VerticalAlignment.Center;

                    //边框
                    XSSFCellStyle cellStyleTitleNew = hssfworkbook.CreateCellStyle() as XSSFCellStyle;
                    cellStyleTitleNew.BorderBottom = BorderStyle.Thin;
                    cellStyleTitleNew.BorderLeft = BorderStyle.Thin;
                    cellStyleTitleNew.BorderRight = BorderStyle.Thin;
                    cellStyleTitleNew.BorderTop = BorderStyle.Thin;

                    //设置单元格的样式：水平对齐居中
                    cellStyleTitleNew.Alignment = HorizontalAlignment.Center;
                    cellStyleTitleNew.VerticalAlignment = VerticalAlignment.Center;

                    //标题行  
                    XSSFRow dataRow = sheet.CreateRow(0) as XSSFRow;
                    for (int i = 0; i < data.Columns.Count; i++)
                    {
                        sheet.SetColumnWidth(i, 100 * 60);
                        if (!string.IsNullOrWhiteSpace(data.Columns[i].ColumnName))
                        {

                            dataRow.CreateCell(i).SetCellValue(data.Columns[i].ColumnName); //列值
                            int width = data.Columns[i].ColumnName.Length;

                            dataRow.GetCell(i).CellStyle = cellStyleTitleNew;
                        }
                        if (selection == 1)
                        {
                            if (i > 1)
                            {
                                dataRow.GetCell(i).CellStyle = style;
                            }
                        }
                    }
                    if (type == 3)
                    {
                        dataRow.Height = 25 * 20;//制定行高25
                    }
                    if (selection == 1)
                    {
                        dataRow.Height = 25 * 20;//制定行高25
                    }
                    string analyte = "";
                    //内容行
                    for (int i = 0; i < data.Rows.Count; i++)
                    {

                        dataRow = sheet.CreateRow(i + from) as XSSFRow;
                        for (int j = 0; j < data.Columns.Count; j++)
                        {
                            //列值
                            Regex regex = new Regex(@"<(.|\n)+?>");
                            var result = regex.Replace(data.Rows[i][j].ToString(), "");
                            var res = data.Rows[i][j];
                            dataRow.CreateCell(j).SetCellValue(result);

                            dataRow.GetCell(j).CellStyle = cellStyleTitleNew;
                            if (type == 3)
                            {
                                if (i == 2 && j > 2)
                                {
                                    dataRow.GetCell(j).CellStyle = style;
                                }
                            }

                            //if (i > 2 && j > 3)
                            //{
                            //    var aa = data.Rows[i][9].ToString();
                            //}

                            if (selection == 1)
                            {
                                if (i >= 0 && j > 1 && !string.IsNullOrEmpty(result) && result == "/")
                                {
                                    dataRow.GetCell(j).CellStyle = style1;
                                }
                            }
                            try
                            {
                                analyte = data.Rows[2][j].ToString();
                                //1。实验室空白：分析项"干物质含量"为空时，标底色
                                //2。非实验室空白：除"干物质含量"分析项外，标底色 
                                if (i > 2 && j > 2 && string.IsNullOrEmpty(result))
                                {

                                    if (Convert.IsDBNull(res))
                                    {
                                        result = "-";
                                        dataRow.CreateCell(j).SetCellValue(result);
                                        dataRow.GetCell(j).CellStyle = style2;
                                    }
                                    else if (!(data.Rows[i]["监测点名称/QC类型"].ToString() != "实验室空白" && data.Rows[2][j].ToString().Contains("干物质含量")))
                                    {
                                        dataRow.GetCell(j).CellStyle = style1;
                                    }
                                }
                                else if (i > 2 && j > 2 && usercode.Equals("luoy") && (analyte.IndexOf("称量样品质量") > -1 || analyte.IndexOf("萃取液体积") > -1))
                                {
                                    dataRow.GetCell(j).CellStyle = style1;
                                }

                            }

                            catch
                            {
                            }
                        }
                        if (type == 3)
                        {
                            dataRow.Height = 25 * 20;//制定行高25
                        }
                        if (selection == 1)
                        {
                            dataRow.Height = 25 * 20;//制定行高25
                        }
                    }


                    ////设置自适应宽度
                    //for (int columnNum = 0; columnNum <= data.Columns.Count; columnNum++)
                    //{
                    //    int columnWidth = (sheet.GetColumnWidth(columnNum) / 256) + 10;
                    //    for (int rowNum = 1; rowNum <= sheet.LastRowNum; rowNum++)
                    //    {
                    //        IRow currentRow = sheet.GetRow(rowNum);
                    //        if (currentRow.GetCell(columnNum) != null)
                    //        {
                    //            NPOI.SS.UserModel.ICell currentCell = currentRow.GetCell(columnNum);
                    //            int length = Encoding.Default.GetBytes(currentCell.ToString()).Length;
                    //            if (columnWidth < length)
                    //            {
                    //                columnWidth = length;
                    //            }
                    //        }

                    //    }
                    //    sheet.SetColumnWidth(columnNum, columnWidth * 256);
                    //}


                    sheet.ForceFormulaRecalculation = true;
                    if (data.Columns.Contains("ID（勿删）"))
                        sheet.SetColumnHidden(0, true);
                    if (data.Columns.Contains("PID（勿删）"))
                        sheet.SetColumnHidden(1, true);
                }

            }
            //hssfworkbook.RemoveSheetAt(0);
            //file.Dispose();
            objStreamWriter.Dispose();
            using (FileStream fileWrite = new FileStream(xlsPath, FileMode.Create))
            {
                hssfworkbook.Write(fileWrite);
                fileWrite.Dispose();
            }
            return saveFileName;
        }