一、使用NPOI导出Excel
//引入NPOI包

• HTML

<input type="button" class="layui-btn layui-btn-blue2 layui-btn-sm" id="ExportExcel" onclick="ExportExcel()" value="导出" />

• JS

    //导出Excel
    function ExportExcel() {
        window.location.href = "@Url.Action("ExportFile")";
    }

• C#

 private readonly Microsoft.AspNetCore.Hosting.IHostingEnvironment _hostingEnvironment;
 public HomeController(Microsoft.AspNetCore.Hosting.IHostingEnvironment hostingEnvironment)
        {
            _hostingEnvironment = hostingEnvironment;
        }


        [HttpGet("ExportFile")]
        //导出文件
        public async Task<IActionResult> ExportFile()
        {
            //获取数据库数据
            var result = await _AnsweringQuestion.GetTeacherName();
            string filePath = "";
            //获取文件路径和名称
            var wwwroot = _hostingEnvironment.WebRootPath;
            var filename = "Table.xlsx";
            filePath = Path.Combine(wwwroot, filename);
            //创建一个工作簿和工作表
            NPOI.XSSF.UserModel.XSSFWorkbook book = new NPOI.XSSF.UserModel.XSSFWorkbook();
            var sheet = book.CreateSheet();
            //创建表头行
            var headerRow = sheet.CreateRow(0);
            headerRow.CreateCell(0).SetCellValue("姓名");
            headerRow.CreateCell(1).SetCellValue("科目");
            headerRow.CreateCell(2).SetCellValue("说明");
            //创建数据行
            var data = result.DataList;
            for (int i = 0; i < data.Count(); i++)
            {
                var dataRow = sheet.CreateRow(i + 1);
                dataRow.CreateCell(0).SetCellValue(data[i].TeacherName);
                dataRow.CreateCell(1).SetCellValue(data[i].TeachSubject); 
                dataRow.CreateCell(2).SetCellValue(data[i].TeacherDesc);
            }
            //将Execel 文件写入磁盘
            using (var f = System.IO.File.OpenWrite(filePath))
            {
                book.Write(f);
            }
            //将Excel 文件作为下载返回给客户端
            var bytes = System.IO.File.ReadAllBytes(filePath);
            return File(bytes, "application/octet-stream", $"{System.DateTime.Now.ToString("yyyyMMdd")}.xlsx");
        }