C# Excel模板導出數據，基於NPOI

1. Excel模板
   
2. Helper類

	public class Helper<T> where T : class, new()
    {
        /// <summary>
        /// 使用模板導出Excel
        /// </summary>
        /// <param name="list">數據</param>
        /// <param name="path">模板路徑</param>
        /// <param name="index">從第幾行插入</param>
        /// <returns></returns>
        public static byte[] TemplateOutput(List<T> list, string path, int index)
        {
            if (list.Count() == 0)
            {
                return new byte[] { };
            }
            using (MemoryStream ms = new MemoryStream())
            {
                var entityProperties = list.FirstOrDefault().GetType().GetProperties();
                string extension = Path.GetExtension(path);
                FileStream fs = File.OpenRead(path);
                IWorkbook workbook = null;
                if (extension.Equals(".xls"))
                {
                    workbook = new HSSFWorkbook(fs);
                }
                else
                {
                    workbook = new XSSFWorkbook(fs);
                }
                fs.Close();
                ISheet sheet = workbook.GetSheetAt(0);
                IRow rows = null;
                int i = 0;
                foreach (var dbitem in list)
                {
                    rows = sheet.CreateRow(i++ + index);
                    for (int j = 0; j < entityProperties.Length; j++)
                    {
                        var prop = entityProperties[j];
                        var value = prop.GetValue(dbitem)?.ToString();
                        rows.CreateCell(j).SetCellValue(value ?? "");
                    }
                }
                workbook.Write(ms);
                return ms.GetBuffer();
            }
        }
    }

3. 導出方法以及涉及對象

//引入的命名空間
using NPOI.HSSF.UserModel;
using NPOI.SS.UserModel;
using NPOI.XSSF.UserModel;
using System.IO;

		/// <summary>
        /// Excel模板導出
        /// </summary>
        public void ExcelExport()
        {
            string templetPath = Context.Server.MapPath("/content/test.xls");
            List<TableStructure> tableStructure = new List<TableStructure>() { 
                new TableStructure()
                {
                    Field = "Id",
                    Type = "int",
                    Desdescribe = "Desdescribe",
                    Remark = "Remark"
                }
            };
            byte[] file = Helper<TableStructure>.TemplateOutput(tableStructure, templetPath, 2);

            Context.Response.ContentType = "application/vnd.ms-excel";
            // 添加頭信息，指定文件名格式   
            Context.Response.AddHeader("Content-Disposition", "attachment;filename=" + DateTime.Now.ToString("yyyyMMddHHmmsss") + ".xls");
            Context.Response.AddHeader("Content-Transfer-Encoding", "binary");
            Context.Response.ContentType = "application/octet-stream";
            Context.Response.ContentEncoding = System.Text.Encoding.UTF8;
            Context.Response.BinaryWrite(file);
        }

        public class TableStructure
        {
            public string Field { get; set; }
            public string Type { get; set; }
            public string Desdescribe { get; set; }
            public string Remark { get; set; }
        }