.netcore 通过文件流形式导出Excel,部分列可写，其它列只读实例

　　具体代码参考：

 [HttpPost("ExportReportList")]
        [ProducesResponseType(typeof(ReportGetListResponse), 200)]
        public async Task<IActionResult> ExportReportList(CreateExportReportBillRequest req)
        {
            try
            {
                var request = new CreateReportBillRequest
                {
                    task_id = req.task_id,
                    startTime = req.startTime,
                    endTime = req.endTime
                };
                if (request.requestHashCode == 0)
                {
                    request.requestHashCode = req.GetHashCode();
                }
                _logger.LogInformation($"【{request.requestHashCode}】导出记录{JsonConvert.SerializeObject(request)}");
                var response = await _reportService.CreateReportBill(request, true);
                if (response.ActionResult == "1")
                {
                    var _reportModel = response.Data as CreateReportBillData;
                    if (_reportModel == null || !_reportModel.signPersons.Any())
                        return Json( new WebApiResult(ApiResultCode.Fail, "无法导出清单"));
                    List<CreateReportBillResponse> lstRep = _reportModel.signPersons;
                    var upStream = GetDeriveStream(lstRep);
                    var file = File(upStream.ToArray(), "application/x-zip-compressed", "AAA.xlsx");
                    upStream.Dispose();
                    return file;
                }
                return null;
              
            }
            catch (Exception ex)
            {

                throw ex;


            }
        }

  private MemoryStream GetDeriveStream(List<CreateReportBillResponse> reportList)
        {
            Dictionary<string, string> header = new Dictionary<string, string>();
            header.Add("user_name", "姓名");
            header.Add("phone_num", "手机号");
            header.Add("pay_cost_str", "本次支付金额");
            header.Add("hidStr", "隐藏列");
            var dt = NpoiHelper.List2DataTable(reportList, header);
            var stream = NpoiHelper.RenderReportDataTableToXLSXStream(dt, MerchantId);
            return stream;
        }

 /// <summary>
        /// List转DataTable
        /// </summary>
        /// <typeparam name="T">实体类型</typeparam>
        /// <param name="list">列表</param>
        /// <param name="header">列头</param>
        /// <returns></returns>
        public static DataTable List2DataTable<T>(List<T> list, IDictionary<string, string> header = null) where T : class
        {
            //如果header无效
            if (header == null || header.Count == 0)
                return GetDataTable(list, typeof(T));

            DataTable dt = new DataTable();

            PropertyInfo[] p = typeof(T).GetProperties();
            foreach (PropertyInfo pi in p)
            {
                //源数据实体是否包含header列
                if (header.ContainsKey(pi.Name))
                {
                    // The the type of the property
                    Type columnType = pi.PropertyType;

                    // We need to check whether the property is NULLABLE
                    if (pi.PropertyType.IsGenericType && pi.PropertyType.GetGenericTypeDefinition() == typeof(Nullable<>))
                    {
                        // If it is NULLABLE, then get the underlying type. eg if "Nullable<int>" then this will return just "int"
                        columnType = pi.PropertyType.GetGenericArguments()[0];
                    }

                    dt.Columns.Add(header[pi.Name], columnType);
                }
            }

            if (list != null)
            {
                for (int i = 0; i < list.Count; i++)
                {
                    IList tempList = new ArrayList();
                    foreach (PropertyInfo pi in p)
                    {
                        object o = pi.GetValue(list[i], null);
                        if (header == null || header.Count == 0 ||  //如果header无效
                            header.ContainsKey(pi.Name))            // 或源数据实体包含header列
                        {
                            tempList.Add(o);
                        }
                    }
                    object[] itm = new object[header.Count];
                    for (int j = 0; j < tempList.Count; j++)
                    {
                        itm.SetValue(tempList[j], j);
                    }
                    dt.LoadDataRow(itm, true);
                }
            }
            List<string> dtColumnList = new List<string>();
            try
            {
                for (int i = 0; i < header.Count; i++)
                {
                    foreach (KeyValuePair<string, string> item in header)
                    {
                        if (dtColumnList.Where(c => c.Equals(item.Value)).FirstOrDefault() == null)
                        {
                            dt.Columns[item.Value].SetOrdinal(i);
                            dtColumnList.Add(item.Value);
                            break;
                        }
                    }
                }
            }
            catch (Exception ex)
            {

                throw;
            }

            return dt;
        }

  public static MemoryStream RenderReportDataTableToXLSXStream(DataTable sourceTable, Guid MerchantId, string sheetName = "Sheet1", string dateTimeFormat = "yyyy-MM-dd HH:mm:ss")
        {
            XSSFWorkbook workbook = new XSSFWorkbook();
            WriteReportToXLSXSheet(workbook, sourceTable, sheetName, dateTimeFormat, MerchantId);
            ISheet sheet = workbook.GetSheetAt(0);
            //设置自适应宽度,9为Excel列数，根据需要自已修改
            for (int columnNum = 0; columnNum <= 2; columnNum++)
            {
                int columnWidth = sheet.GetColumnWidth(columnNum) / 256;
                //5为开始修改的行数，默认为0行开始
                for (int rowNum = 5; rowNum <= sheet.LastRowNum; rowNum++)
                {
                    IRow currentRow = sheet.GetRow(rowNum);
                    if (currentRow.GetCell(columnNum) != null)
                    {
                        ICell currentCell = currentRow.GetCell(columnNum);
                        int length = Encoding.Default.GetBytes(currentCell.ToString()).Length+1;
                        if (columnWidth < length)
                        {
                            columnWidth = length;
                        }
                    }
                }
                sheet.SetColumnWidth(columnNum, columnWidth * 256);
            }
            MemoryStream ms = new MemoryStream();
            workbook.Write(ms, true);
            ms.Seek(0, SeekOrigin.Begin);
            return ms;
        }

 /// <summary>
        ///  将数据内容写入Office2007版本以后的Excel对应的Sheet中
        /// </summary>
        /// <param name="workBook"></param>
        /// <param name="sourceTable">将要写入的数据源</param>
        /// <param name="sheetName">Sheet名称</param>
        /// <param name="dateTimeFormat">时间格式化方式</param>
        private static void WriteReportToXLSXSheet(IWorkbook workBook, DataTable sourceTable, string sheetName, string dateTimeFormat,Guid MerchantId)
        {
            ISheet sheet = workBook.CreateSheet(sheetName);
            workBook.GetSheetAt(0).ProtectSheet(MerchantId.ToString());
            //解除锁定样式
            ICellStyle cellstyleUnLock = workBook.CreateCellStyle();
            cellstyleUnLock.IsLocked = false;//解锁
            //锁定样式
            ICellStyle style1 = workBook.CreateCellStyle();
            style1.IsLocked = true;//上锁

            //设置字体
            IFont font1 =  workBook.CreateFont();
            //给样式设置字体
            style1.SetFont(font1);
            style1.IsLocked = true;
            font1.FontHeightInPoints = 12;
            font1.FontName = "等线";
            font1.Color = HSSFColor.Red.Index;
            IRow des1 = sheet.CreateRow(0);
            des1.CreateCell(0).SetCellValue("必读！说明：");
            des1.GetCell(0).CellStyle = style1;
            IRow des2 = sheet.CreateRow(1);
            des2.CreateCell(0).SetCellValue("1、A");
            des2.GetCell(0).CellStyle = style1;
            IRow des3 = sheet.CreateRow(2);
            des3.CreateCell(0).SetCellValue("2、B");
            des3.GetCell(0).CellStyle = style1;
            IRow des4 = sheet.CreateRow(3);
            des4.CreateCell(0).SetCellValue("3、C");
            des4.GetCell(0).CellStyle = style1;
            IRow des5 = sheet.CreateRow(4);
            des5.CreateCell(0).SetCellValue("4、D");
            des5.GetCell(0).CellStyle = style1;

            IRow headerRow = sheet.CreateRow(5);//从第6行开始写入标题
            sheet.SetColumnHidden(10,true);//隐藏传值
            foreach (DataColumn column in sourceTable.Columns)
                headerRow.CreateCell(column.Ordinal).SetCellValue(column.ColumnName);

            int rowIndex = 6;//从第7行开始写入值
            foreach (DataRow row in sourceTable.Rows)
            {
                IRow dataRow = sheet.CreateRow(rowIndex);
                IDataFormat dataformat = workBook.CreateDataFormat();
                ICellStyle style = workBook.CreateCellStyle();
                style.IsLocked = true;
                foreach (DataColumn column in sourceTable.Columns)
                {
                   
                    if (row[column] is DBNull)
                    {
                        dataRow.CreateCell(column.Ordinal).SetCellValue(string.Empty);
                        continue;
                    }

                    if (column.DataType == typeof(int))
                    {
                        dataRow.CreateCell(column.Ordinal).SetCellValue((int)row[column]);
                    }
                    else if (column.DataType == typeof(float))
                    {
                        dataRow.CreateCell(column.Ordinal).SetCellValue((float)row[column]);
                    }
                    else if (column.DataType == typeof(double))
                    {
                        dataRow.CreateCell(column.Ordinal).SetCellValue((double)row[column]);
                    }
                    else if (column.DataType == typeof(Byte))
                    {
                        dataRow.CreateCell(column.Ordinal).SetCellValue((byte)row[column]);
                    }
                    else if (column.DataType == typeof(UInt16))
                    {
                        dataRow.CreateCell(column.Ordinal).SetCellValue((UInt16)row[column]);
                    }
                    else if (column.DataType == typeof(UInt32))
                    {
                        dataRow.CreateCell(column.Ordinal).SetCellValue((UInt32)row[column]);
                    }
                    else if (column.DataType == typeof(UInt64))
                    {
                        dataRow.CreateCell(column.Ordinal).SetCellValue((UInt64)row[column]);
                    }
                    else if (column.DataType == typeof(DateTime))
                    {
                        dataRow.CreateCell(column.Ordinal).SetCellValue((DateTime)row[column]);
                        style.DataFormat = dataformat.GetFormat(dateTimeFormat);
                        dataRow.GetCell(column.Ordinal).CellStyle = style;
                    }
                    else
                    {
                        dataRow.CreateCell(column.Ordinal).SetCellValue(Convert.ToString(row[column]));
                    }
                    if (column.ColumnName != "本次支付金额")
                        dataRow.GetCell(column.Ordinal).CellStyle = style;
                    else
                        dataRow.GetCell(column.Ordinal).CellStyle = cellstyleUnLock;
                }
                rowIndex++;
            }
           
        }