按Excel的模板导出数据

思路：把Excel模板上传到服务器；然后读取文档，写入数据，另存为新的文件

然后就是导出的时候处理数据定义的字符串，按数据导出；注意读取的数据流要处理下，不然会报异常

        public Stream GetExcelStream(op_client_template_mapping model)//model  配置文件模型
        {
            string fileUrl = _BillFileService.GetHttp() + "/" + model.filePath + "/" + model.fileNames;
            return WebRequest.Create(fileUrl).GetResponse().GetResponseStream();
        }
        //文件里转换成能处理的流
        public MemoryStream StreamToMemoryStream(Stream instream)
        {
            MemoryStream outstream = new MemoryStream();
            const int bufferLen = ;
            byte[] buffer = new byte[bufferLen];
            int count = ;
            while ((count = instream.Read(buffer, , bufferLen)) > )
            {
                outstream.Write(buffer, , count);
            }
            return outstream;
        }

导出数据大概

public void AsposeToExcel<T>(List<T> data, ExcelModel excelModel, op_client_template_mapping mapping, string path)
        {
            try
            {
                Stream sm = GetExcelStream(mapping);
                var ms = StreamToMemoryStream(sm);
                ms.Seek(, SeekOrigin.Begin); int buffsize = (int)ms.Length; //rs.Length 此流不支持查找,先转为MemoryStream
                byte[] bytes = new byte[buffsize];

                ms.Read(bytes, , buffsize);
                Workbook workbook = new Workbook(ms);
                ms.Flush(); ms.Close();
                sm.Flush(); sm.Close();
                Worksheet worksheet = workbook.Worksheets[]; //工作表

                if (excelModel.Title != null && !string.IsNullOrEmpty(excelModel.Title?.cloumnName))
                {
                    SetTitle(worksheet, excelModel.Title.cloumnName, excelModel.Title.Letter + excelModel.Title.Index);
                }
                SetCellData(worksheet, data, excelModel);

                workbook.Save(path);
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.ToString());
            }
        }

        private static void SetTitle(Worksheet sheet, string title, string index)
        {
            sheet.Cells[index].PutValue(title);
        }

        /// <summary>
        /// 填充字段
        /// </summary>
        private static void SetCellData<T>(Worksheet sheet, List<T> data, ExcelModel excelModel)
        {
            var noData = excelModel.ExcelCloumns.Where(it => it.colunmEnglish.Equals(""));//没有绑定的数据取默认值
            int i = ;
            foreach (T item in data)
            {
                foreach (PropertyDescriptor pd in TypeDescriptor.GetProperties(typeof(T)))
                {
                    var column = excelModel.ExcelCloumns.Where(it => it.colunmEnglish.Equals(pd.Name)).FirstOrDefault();
                    if (column != null)//存在该字段就赋值
                    {
                        int row = column.Index + i;
                        if (pd.PropertyType.ToString() == "System.DateTime")
                        {
                            sheet.Cells[column.Letter + row].PutValue(pd.GetValue(item).ToString());//（column.Letter + row）等于 A2，C2这样赋值
                        }
                        else
                        {
                            sheet.Cells[column.Letter + row].PutValue(pd.GetValue(item));
                        }
                    }
                }
                foreach (var it in noData)//赋值默认值
                {
                    int row = it.Index + i;
                    if (it.cloumnName == "序号")
                    {
                        sheet.Cells[it.Letter + row].PutValue(i+);
                    }
                    else
                    {
                        sheet.Cells[it.Letter + row].PutValue(it.DefaultValue ?? "");
                    }
                }
                i++;
            }
            sheet.AutoFitColumns();
        }
        #endregion