NetCore3.1 NPOI 读取Excel中的数据，Excel导出------如何将文件转为：IFormFile 及NetCore3.1下载文件

十年河东，十年河西，莫欺少年穷

学无止境，精益求精

好久没写博客了，太忙了.......................................................

代码类东西，不想多说，自己看吧，需要引用NPOI 包。

1、将文件转为IFormFile

        /// <summary>
        /// c://path/to/test.jpg
        /// </summary>
        /// <param name="fileName">绝对路径</param>
        /// <returns></returns>
        public static IFormFile GetFormFileByFileName(string fileName)
        {
            var FileBytes = File.ReadAllBytes(fileName);
            using (var ms = new MemoryStream(FileBytes))
            {
                IFormFile fromFile = new FormFile(ms, 0, ms.Length,
                    Path.GetFileNameWithoutExtension(fileName),
                    Path.GetFileName(fileName));
                return fromFile;
            }
        }

2、读取Excel文件

先建一个实体类：

    public class student
    {
        public string Name { get; set; }
        public string Age { get; set; }
    }

Api方法如下：

        /// <summary>
        /// 获取Excel中的数据
        /// </summary>
        /// <param name="fileName"></param>
        /// <param name="ColumnNumber"></param>
        /// <returns></returns>
        [HttpGet]
        [Route("GetExcelStudents")]
        public IActionResult GetExcelStudents(string fileName, int ColumnNumber)
        {
            List<string> err = new List<string>();
            var result = _HardwareService.GetExcelStudents(fileName, ColumnNumber,ref err);
            return Ok(result);
        }

服务层方法如下：

/// <summary>
        /// 绝对路径+文件名称  D:gitProject	est2.xls
        /// </summary>
        /// <param name="fileName"></param>
        /// <param name="ColumnNumber">读取的列数</param>
        /// <param name="RefErrors">报错处理</param>
        /// <returns></returns>
        public BaseResponse<List<student>> GetExcelStudents(string fileName, int ColumnNumber,ref List<string> RefErrors)
        {
            var Data = new List<student>();
            var Error = new List<string>();
            var FileBytes = File.ReadAllBytes(fileName);
            using (var ms = new MemoryStream(FileBytes))
            {
                IFormFile file = new FormFile(ms, 0, ms.Length,
                    Path.GetFileNameWithoutExtension(fileName),
                    Path.GetFileName(fileName));

                //定义一个bool类型的变量用来做验证

                bool flag = true;
                try
                {
                    string fileExt = Path.GetExtension(file.FileName).ToLower();
                    //定义一个集合一会儿将数据存储进来,全部一次丢到数据库中保存

                    MemoryStream mss = new MemoryStream();
                    file.CopyTo(mss);
                    mss.Seek(0, SeekOrigin.Begin);
                    IWorkbook book;
                    if (fileExt == ".xlsx")
                    {
                        book = new XSSFWorkbook(mss);
                    }
                    else if (fileExt == ".xls")
                    {
                        book = new HSSFWorkbook(mss);
                    }
                    else
                    {
                        book = null;
                    }
                    ISheet sheet = book.GetSheetAt(0);

                    int CountRow = sheet.LastRowNum + 1;//获取总行数

                    if (CountRow - 1 == 0)
                    {
                        return null;

                    }
                    #region 循环验证
                    for (int i = 1; i < CountRow; i++)
                    {
                        //获取第i行的数据
                        var row = sheet.GetRow(i);
                        if (row != null)
                        {
                            //循环的验证单元格中的数据
                            for (int j = 0; j < ColumnNumber; j++)
                            {
                                if (row.GetCell(j) == null || row.GetCell(j).ToString().Trim().Length == 0)
                                {
                                    flag = false;
                                    Error.Add($"第{i + 1}行,第{j + 1}列数据不能为空。");
                                }
                            }
                        }
                    }
                    #endregion
                    if (flag)
                    {
                        for (int i = 1; i < CountRow; i++)
                        {
                            //实例化实体对象
                            student studentM = new student();
                            var row = sheet.GetRow(i);

                            if (row.GetCell(0) != null && row.GetCell(0).ToString().Trim().Length > 0)
                            {
                                studentM.Name = row.GetCell(0).ToString();
                            }
                            if (row.GetCell(1) != null && row.GetCell(1).ToString().Trim().Length > 0)
                            {
                                studentM.Age = row.GetCell(1).ToString();
                            }
                            Data.Add(studentM);
                        }
                    }
                    if (!flag)
                    {
                        RefErrors = Error;
                    }
                }
                catch (Exception ex)
                {
                    return CommonBaseResponse.SetResponse<List<student>>(null, false, ex.ToString());
                }
            }


            return CommonBaseResponse.SetResponse<List<student>>(Data, true);
        }

最后，我们看看我的Excel文件长啥样

webAPI请求参数：

  最最后，我们看看webAPI执行的结果，如下

 从结果中我们得知，读取过程中自动跳过了标题。

如何下载文件

第一步，在构造函数中注入通用主机

  private readonly IHostingEnvironment _hostingEnvironment;
        private readonly ISysGroupInfos _Service;
        private readonly IHardware _HardwareService;
        /// <summary>
        /// 构造函数注入
        /// </summary>
        /// <param name="service"></param>
        /// <param name="hardwareService"></param>
        /// <param name="hostingEnvironment"></param>
        public HardwareController(ISysGroupInfos service,IHardware hardwareService,IHostingEnvironment hostingEnvironment)
        {
            _hostingEnvironment = hostingEnvironment;
            _Service = service;
            _HardwareService = hardwareService;
        }

第二步，读取到项目工作的目录

 string contentRootPath = _hostingEnvironment.ContentRootPath

最后，就可以转化为文件流进行下载了，如下：

        /// <summary>
        /// 下载模板
        /// </summary>
        /// <returns></returns>
        [HttpGet]
        [Route("DowmLoadBatteryFile")]
        public IActionResult DowmLoadBatteryFile()
        {
            string contentRootPath = _hostingEnvironment.ContentRootPath+ "/Template/BatteryNos.xlsx";
            var stream = System.IO.File.OpenRead(contentRootPath);
            return File(stream, "application/vnd.android.package-archive", Path.GetFileName(contentRootPath));
        }

我的项目结构如下：

 针对这种方式，VUE下载的方法我也贴出来，如下：

 downloads() {
      let that = this;
      that
        .$axios({
          url: "/Api/V2/Hardware/DowmLoadBatteryFile",
          method: "get",
          responseType:"blob"
        })
        .then(function (response) {
          let blob = new Blob([response.data], { type: response.data.type });
        // 针对于 IE 浏览器的处理, 因部分 IE 浏览器不支持 createObjectURL
        if (window.navigator && window.navigator.msSaveOrOpenBlob) {
          window.navigator.msSaveOrOpenBlob(blob, response.fileName);
        } else {
          var downloadElement = document.createElement("a");
          var href = window.URL.createObjectURL(blob); // 创建下载的链接
          downloadElement.href = href;
          downloadElement.download = response.fileName; // 下载后文件名
          document.body.appendChild(downloadElement);
          downloadElement.click(); // 点击下载
          document.body.removeChild(downloadElement); // 下载完成移除元素
          window.URL.revokeObjectURL(href); // 释放掉 blob 对象
        }
        })
        .catch(function (error) {
          console.log(error);
        });
    },

 当然，还有几种下载方法，虚拟路径方式

// <summary>
        /// 虚拟文件地址输出下载
        /// </summary>
        /// <returns></returns>
        public IActionResult OnPostDown()
        {
            var addrUrl = "/bak/love.xls";
            return File(addrUrl, "application/vnd.android.package-archive", Path.GetFileName(addrUrl));
        }

HttClient方式下载

        /// <summary>
        /// 通过HttpClient获取另外站点的文件流，再输出
        /// </summary>
        /// <returns></returns>
        public async Task<IActionResult> OnPostDown02()
        {
            var path = "https://files.cnblogs.com/files/wangrudong003/%E7%89%B9%E4%BB%B701.gif";
            HttpClient client = new HttpClient();
            client.BaseAddress = new Uri(path);
            var stream = await client.GetStreamAsync(path);
            return File(stream, "application/vnd.android.package-archive", Path.GetFileName(path));
        }

多种方案请参考   https://www.cnblogs.com/wangrudong003/p/7592689.html

导出Excel:

公共类：

using NPOI.HSSF.UserModel;
using NPOI.SS.UserModel;
using NPOI.XSSF.UserModel;
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Configuration;
using System.Data;
using System.IO;
using System.Reflection;
using System.Text;

namespace WuAnCommon
{
 public static class ExcelHelper
    {
        public static byte[] DataTableToExcel(DataTable table, string title = null, string sheetName = "Sheet")
        {
            IWorkbook workbook = new XSSFWorkbook();
            ISheet sheet = workbook.CreateSheet(sheetName);
            int cellsIndex = 0;
            // 填充表头
            IRow cellsHeader = sheet.CreateRow(cellsIndex);
            for (int i = 0; i < table.Columns.Count; i++)
            {
                cellsHeader.CreateCell(i).SetCellValue(table.Columns[i].ColumnName);
            }
            // 填充数据
            cellsIndex += 1;
            foreach (DataRow dr in table.Rows)
            {
                IRow row = sheet.CreateRow(cellsIndex);
                for (int i = 0; i < table.Columns.Count; i++)
                {
                    row.CreateCell(i).SetCellValue(ToString(dr[i]));
                }
                cellsIndex++;
            }
            byte[] buffer = null;
            using (MemoryStream ms = new MemoryStream())
            {
                workbook.Write(ms);
                buffer = ms.GetBuffer();
                ms.Close();
            }
            return buffer;
        }
        public static byte[] ExortToExcel<T>(IList<T> data, string title = null, string sheetName = "Sheet") where T : class, new()
        {
            IWorkbook workbook = new XSSFWorkbook();
            ISheet sheet = workbook.CreateSheet(sheetName);
            ICellStyle headerStyle = workbook.CreateCellStyle();
            //ICellStyle dataStyle = workbook.CreateCellStyle();
            IFont f = workbook.CreateFont();
            f.Boldweight = (short)FontBoldWeight.Bold;
            headerStyle.SetFont(f);

            int cellsIndex = 0;
            var propertyInfos = TypeDescriptor.GetProperties(typeof(T));

            // 标题
            if (!string.IsNullOrEmpty(title))
            {
                // 填充数据
                IRow cellsTitle = sheet.CreateRow(0);
                var cell = cellsTitle.CreateCell(0);
                cell.CellStyle = headerStyle;
                cell.SetCellValue(title);
                // 合并单元格
                sheet.AddMergedRegion(new NPOI.SS.Util.CellRangeAddress(0, 1, 0, propertyInfos.Count - 1));
                cellsIndex = 2;
            }


            // 填充表头
            IRow cellsHeader = sheet.CreateRow(cellsIndex);
            var colIndex = 0;
            for (int i = 0; i < propertyInfos.Count; i++)
            {
                var p = propertyInfos[i];
                if (p.IsBrowsable && !string.IsNullOrEmpty(p.Description))
                {
                    var cell = cellsHeader.CreateCell(colIndex++);
                    cell.CellStyle = headerStyle;
                    cell.SetCellValue(p.Description);
                }
            }


            cellsIndex += 1;
            // 填充数据
            foreach (var item in data)
            {
                IRow row = sheet.CreateRow(cellsIndex++);
                colIndex = 0;
                for (int i = 0; i < propertyInfos.Count; i++)
                {
                    var p = propertyInfos[i];
                    if (p.IsBrowsable && !string.IsNullOrEmpty(p.Description))
                    {
                        var value = p.GetValue(item);

                        var cell = row.CreateCell(colIndex++);
                        //cell.CellStyle = headerStyle;
                        cell.SetCellValue(ToString(value));
                    }
                }
            }

            //重置自适应
            for (int i = 0; i < cellsHeader.Cells.Count; i++)
            {
                sheet.AutoSizeColumn(i);
            }

            byte[] buffer = null;
            using (MemoryStream ms = new MemoryStream())
            {
                workbook.Write(ms);
                buffer = ms.GetBuffer();
                ms.Close();
            }
            return buffer;
        }
        public static string ToString(Object data) {
            if (data == null) {
                return "";
            } else if (data.ToString().StartsWith("0")) {
                return  data.ToString();
            }
            return data.ToString();
        }
        public static T2 ConvertToModel<T1, T2>(T1 source)
        {
            T2 model = default(T2);
            PropertyInfo[] pi = typeof(T2).GetProperties();
            PropertyInfo[] pi1 = typeof(T1).GetProperties();
            model = Activator.CreateInstance<T2>();
            foreach (var p in pi)
            {
                foreach (var p1 in pi1)
                {
                    if (p.Name == p1.Name)
                    {
                        p.SetValue(model, p1.GetValue(source, null), null);
                        break;
                    }
                }
            }
            return model;
        }
        public static void AddCellPicture(ISheet sheet, HSSFWorkbook workbook, string fileurl, int row, int col)
        {
            try
            {
                WriteSqlLog("AddCellPicture", fileurl+"|"+row+"|"+col);
                //由于File类只能读取本地资源，所以在配置文件中配置了物理路径的前半部分
                string FileName = fileurl;
                if (File.Exists(FileName) == true)
                {
                    byte[] bytes = System.IO.File.ReadAllBytes(FileName);
                    if (!string.IsNullOrEmpty(FileName))
                    {
                        int pictureIdx = workbook.AddPicture(bytes, NPOI.SS.UserModel.PictureType.PNG);
                        HSSFPatriarch patriarch = (HSSFPatriarch)sheet.CreateDrawingPatriarch();
                        HSSFClientAnchor anchor = new HSSFClientAnchor(0, 0, 0, 0, col, row, col + 1, row + 1);
                        HSSFPicture pict = (HSSFPicture)patriarch.CreatePicture(anchor, pictureIdx);
                    }
                }
            }
            catch (Exception ex)
            {
                WriteSqlLog("AddCellPictureException", ex.ToString());
                throw ex;
            }
        }
        public static void WriteSqlLog(string action, string strMessage)
        {
            string path = AppDomain.CurrentDomain.BaseDirectory + @"Log1";
            if (!System.IO.Directory.Exists(path))
                System.IO.Directory.CreateDirectory(path);
            DateTime time = DateTime.Now;
            string fileFullPath = path + time.ToString("yyyy-MM-dd") + ".txt";
            StringBuilder str = new StringBuilder();
            str.Append("Time:    " + time.ToString() + "
");
            str.Append("Action:  " + action + "
");
            str.Append("Message: " + strMessage + "
");
            str.Append("-----------------------------------------------------------

");
            System.IO.StreamWriter sw;
            if (!File.Exists(fileFullPath))
            {
                sw = File.CreateText(fileFullPath);
            }
            else
            {
                sw = File.AppendText(fileFullPath);
            }
            sw.WriteLine(str.ToString());
            sw.Close();
        }
    }
}

实体类：

    public class CabinetOrderModel
    {
        public int GroupId { get; set; }
        public string UID { get; set; }
        [Description("提现编号")]
        public string OrderNo { get; set; }
        [Description("客户手机号")]
        public string CustomerPhone { get; set; }
        [Description("客户姓名")]
        public string CustomerUserName { get; set; }

        [Description("订单金额")]
        public decimal OrderPrice { get; set; }
        [Description("支付金额")]
        public decimal PayMoney { get; set; }
        [Description("平台成本价")]
        public decimal centerfrmoney { get; set; }
        [Description("一级加价")]
        public decimal parentfrmoney { get; set; }
        [Description("购买充电时长")]
        public string BuyTime { get; set; }
        [Description("所属商家")]
        public string GroupName { get; set; }
        public int GroupLevel { get; set; }
        public string Province { get; set; }
        public string City { get; set; }
        public string RegionID { get; set; }

        public string PayGroup { get; set; }
        public int PayStatus { get; set; }
        public DateTime PayTime { get; set; }
        public int PayType { get; set; }
        public DateTime AddTime { get; set; }
        [Description("订单时间")]
        public DateTime OrderTime { get; set; }
        public string GroupPhone { get; set; }
        [Description("商家利润")]
        public decimal LRMoney { get; set; }

        public int Status { get; set; }
        [Description("订单状态")]
        public string StatusCn { get { return GetStatus(this.Status); } }
        private string GetStatus(int Status)
        {
            string s = string.Empty;
            switch (Status)
            {
                case 0: s = "待支付"; break;
                case 1: s = "待使用"; break;
                case 2: s = "使用中"; break;
                case 3: s = "已使用"; break;
                case 4: s = "已取消"; break;
            }
            return s;
        }
        public string OrderId { get; set; }
        public string GoodsName { get; set; }

        public string GoodsNo { get; set; }
        public string Count { get; set; }
        public string RemainderCount { get; set; }
        public DateTime? StartTime { get; set; }
        public DateTime? EndTime { get; set; }
        public int TimeType { get; set; }
        public string BusinessType { get; set; }
        public string AreaCode { get; set; }
        public bool IsDirect { get; set; }
    }

控制器方法：

 /// <summary>
        /// 导出换电订单
        /// </summary>
        /// <param name="Data"></param>
        /// <returns></returns>
        [HttpPost]
        [Route("ExcelCabinetOrder")]
        public IActionResult ExcelCabinetOrder([FromBody] SearchCabinetOrderModel Data)
        {
            BasePaginationModel pagination = new BasePaginationModel()
            {
                pageNumber = 1,
                pageSize = 10000000
            }; 
            var name = "换电订单";
            var result = _Service.ExcelCabinetOrder(Data, CurrentUser, ref pagination);
            return File(result, "application/octet-stream", $"{name}_{DateTime.Now:yyyyMMddHHmmssfff}.xlsx");
        }

服务方法：

        /// <summary>
        /// 导出
        /// </summary>
        /// <param name="search"></param>
        /// <param name="CurrentUser"></param>
        /// <returns></returns>
        public byte[] ExcelCabinetOrder(SearchCabinetOrderModel search, CurrentUserData CurrentUser, ref BasePaginationModel Pagination)
        {
            var result = SearchCabinetOrder(search, CurrentUser, ref Pagination);
            return ExcelHelper.ExortToExcel<CabinetOrderModel>(result.data.data, "换电订单", "换电订单");
        }

Result.data.data  其实就是一个List<T> 集合

效果：

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