1.添加依赖 DotNetCore.NPOI

2.读取Excel类库

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;

using System.IO;
using System.Reflection;
using System.Collections;
using System.Data;
using NPOI.SS.UserModel;

namespace SVW_ReOnLine.BLL.Common
{
    /// <summary>
    /// Summary description for OfficeHelper
    /// </summary>
    public class OfficeHelper
    {
        /// <summary>
        /// 将excel文件内容读取到DataTable数据表中
        /// </summary>
        /// <param name="fileName">文件完整路径名</param>
        /// <param name="sheetName">指定读取excel工作薄sheet的名称</param>
        /// <param name="isFirstRowColumn">第一行是否是DataTable的列名：true=是，false=否</param>
        /// <returns>DataTable数据表</returns>
        public static DataTable ReadExcelToDataTable(string fileName, string sheetName = null, bool isFirstRowColumn = true)
        {
            //定义要返回的datatable对象
            DataTable data = new DataTable();
            //excel工作表
            ISheet sheet = null;
            //数据开始行(排除标题行)
            int startRow = 0;
            try
            {
                if (!File.Exists(fileName))
                {
                    return null;
                }
                //根据指定路径读取文件
                FileStream fs = new FileStream(fileName, FileMode.Open, FileAccess.Read);
                //根据文件流创建excel数据结构
                IWorkbook workbook = WorkbookFactory.Create(fs);
                //IWorkbook workbook = new HSSFWorkbook(fs);
                //如果有指定工作表名称
                if (!string.IsNullOrEmpty(sheetName))
                {
                    sheet = workbook.GetSheet(sheetName);
                    //如果没有找到指定的sheetName对应的sheet，则尝试获取第一个sheet
                    if (sheet == null)
                    {
                        sheet = workbook.GetSheetAt(0);
                    }
                }
                else
                {
                    //如果没有指定的sheetName，则尝试获取第一个sheet
                    sheet = workbook.GetSheetAt(0);
                }
                if (sheet != null)
                {
                    IRow firstRow = sheet.GetRow(0);
                    //一行最后一个cell的编号 即总的列数
                    int cellCount = firstRow.LastCellNum;
                    //如果第一行是标题列名
                    if (isFirstRowColumn)
                    {
                        for (int i = firstRow.FirstCellNum; i < cellCount; ++i)
                        {
                            ICell cell = firstRow.GetCell(i);
                            if (cell != null)
                            {
                                string cellValue = cell.StringCellValue;
                                if (cellValue != null)
                                {
                                    DataColumn column = new DataColumn(cellValue);
                                    data.Columns.Add(column);
                                }
                            }
                        }
                        startRow = sheet.FirstRowNum + 1;
                    }
                    else
                    {
                        startRow = sheet.FirstRowNum;
                    }
                    //最后一列的标号
                    int rowCount = sheet.LastRowNum;
                    for (int i = startRow; i <= rowCount; ++i)
                    {
                        IRow row = sheet.GetRow(i);
                        if (row == null) continue; //没有数据的行默认是null　　　　　　　

                        DataRow dataRow = data.NewRow();
                        for (int j = row.FirstCellNum; j < cellCount; ++j)
                        {
                            if (row.GetCell(j) != null) //同理，没有数据的单元格都默认是null
                                dataRow[j] = row.GetCell(j).ToString();
                        }
                        data.Rows.Add(dataRow);
                    }
                }
                return data;
            }
            catch (Exception ex)
            {
                throw ex;
            }
        }

        /// <summary>
        /// 将文件流读取到DataTable数据表中
        /// </summary>
        /// <param name="fileStream">文件流</param>
        /// <param name="sheetName">指定读取excel工作薄sheet的名称</param>
        /// <param name="isFirstRowColumn">第一行是否是DataTable的列名：true=是，false=否</param>
        /// <returns>DataTable数据表</returns>
        public static DataTable ReadStreamToDataTable(Stream fileStream, string sheetName = null, bool isFirstRowColumn = true)
        {
            //定义要返回的datatable对象
            DataTable data = new DataTable();
            //excel工作表
            ISheet sheet = null;
            //数据开始行(排除标题行)
            int startRow = 0;
            try
            {
                //根据文件流创建excel数据结构,NPOI的工厂类WorkbookFactory会自动识别excel版本，创建出不同的excel数据结构
                IWorkbook workbook = WorkbookFactory.Create(fileStream);
                //如果有指定工作表名称
                if (!string.IsNullOrEmpty(sheetName))
                {
                    sheet = workbook.GetSheet(sheetName);
                    //如果没有找到指定的sheetName对应的sheet，则尝试获取第一个sheet
                    if (sheet == null)
                    {
                        sheet = workbook.GetSheetAt(0);
                    }
                }
                else
                {
                    //如果没有指定的sheetName，则尝试获取第一个sheet
                    sheet = workbook.GetSheetAt(0);
                }
                if (sheet != null)
                {
                    IRow firstRow = sheet.GetRow(0);
                    //一行最后一个cell的编号 即总的列数
                    int cellCount = firstRow.LastCellNum;
                    //如果第一行是标题列名
                    if (isFirstRowColumn)
                    {
                        for (int i = firstRow.FirstCellNum; i < cellCount; ++i)
                        {
                            ICell cell = firstRow.GetCell(i);
                            if (cell != null)
                            {
                                string cellValue = cell.StringCellValue;
                                if (cellValue != null)
                                {
                                    DataColumn column = new DataColumn(cellValue);
                                    data.Columns.Add(column);
                                }
                            }
                        }
                        startRow = sheet.FirstRowNum + 1;
                    }
                    else
                    {
                        startRow = sheet.FirstRowNum;
                    }
                    //最后一列的标号
                    int rowCount = sheet.LastRowNum;
                    for (int i = startRow; i <= rowCount; ++i)
                    {
                        IRow row = sheet.GetRow(i);
                        if (row == null || row.FirstCellNum < 0) continue; //没有数据的行默认是null　　　　　　　

                        DataRow dataRow = data.NewRow();
                        for (int j = row.FirstCellNum; j < cellCount; ++j)
                        {
                            //同理，没有数据的单元格都默认是null
                            ICell cell = row.GetCell(j);
                            if (cell != null)
                            {
                                if (cell.CellType == CellType.Numeric)
                                {
                                    //判断是否日期类型
                                    if (DateUtil.IsCellDateFormatted(cell))
                                    {
                                        dataRow[j] = row.GetCell(j).DateCellValue;
                                    }
                                    else
                                    {
                                        dataRow[j] = row.GetCell(j).ToString().Trim();
                                    }
                                }
                                else
                                {
                                    dataRow[j] = row.GetCell(j).ToString().Trim();
                                }
                            }
                        }
                        data.Rows.Add(dataRow);
                    }
                }
                return data;
            }
            catch (Exception ex)
            {
                throw ex;
            }
        }
    }
}

3.控制器端Controller

public class UploadController : Controller
    {
        private ILog log = LogManager.GetLogger(Startup.repository.Name, typeof(UploadController));
        private IHostingEnvironment hostingEnv;
        public UploadController(IHostingEnvironment env)
        {
            this.hostingEnv = env;
        }
        [HttpPost]
        public JsonResult UploadFilesAjax()
        {
            JArray lst = new JArray();
            JObject jsonResult = new JObject();
            int result = 0;
            //long size = 0;
            string fileNamePath = string.Empty;
            string RequestPath = string.Empty;
            try
            {
                //string domurl = @"http://dy.dt1.biz/upload/";
                string domurl = @"http://localhost:57663/upload/";
                var files = Request.Form.Files;
                foreach (var file in files)
                {
                    string fileName = DateTime.Now.ToString("MMddHHmmss") + file.FileName;
                    fileNamePath = Path.Combine("upload", fileName);
                    string serverUrl = Request.HttpContext.Connection.LocalIpAddress.ToStringExt() + ":" + Request.HttpContext.Connection.LocalPort.ToStringExt() + @"/upload/DeviceImage.jpg";
                    log.Info("客户端IP地址2：" + serverUrl);
                    RequestPath = domurl + fileName;
                    //size += file.Length;

                    //保存文件
                    //物理路径 
                    string SavePath=Path.Combine(hostingEnv.WebRootPath, fileNamePath);
                    using (FileStream fs = new FileStream(SavePath, FileMode.CreateNew))
                    {
                        file.CopyTo(fs);
                        fs.Flush();
                        result = 1;
                    }

                    DataTable dt=  OfficeHelper.ReadExcelToDataTable(SavePath);
                    for (int i = 0; i < dt.Rows.Count; i++)
                    {
                        JObject obj = new JObject();
                        for (int j = 0; j < dt.Columns.Count; j++)
                        {

                            obj.Add("col"+j.ToString(), dt.Rows[i][j].ToStringExt());

                        }
                        lst.Add(obj);
                    }


                }
                //string url = Request.HttpContext.Connection.RemoteIpAddress.ToStringExt()+":"+ Request.HttpContext.Connection.RemotePort.ToStringExt();
                jsonResult.Add("Result", result);
                jsonResult.Add("ImageUrl", RequestPath);
                jsonResult.Add("Data", lst);
            }
            catch (Exception ex)
            {
                log.Error("上传文件错误信息列表错误：" + ex.ToStringExt());
                jsonResult.Add("Result", result);
            }
            return Json(jsonResult);
        }

4. index.html

<!DOCTYPE html>
<html>

<head>
    <meta charset="utf-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1">
    <title>用户登陆</title>
    <link href="/css/bootstrap.min.css" rel="stylesheet">
    <style>
        .panel {
            width: 375px;
            margin: 15px auto;
        }

        #submit {
            width: 100%;
        }

        img {
            width: 100%;
        }

        .breadcrumb {
            margin-bottom: 10px;
        }

        @media screen and (max-width: 480px) {
            .panel {
                width: 100%;
                margin: 0;
                border: 0;
                box-shadow: none;
            }
        }
    </style>
</head>

<body>
    <div class="panel panel-default">
        <div class="panel-heading" align="center"><b>用户登陆</b></div>
        <div class="panel-body">

                <input type="file" id="files" name="files" multiple />
                <input type="button" id="uploadExcel" value="Upload Selected Files" />

        </div>
    </div>
    <script src="/js/jquery.min.js"></script>
    <script src="/js/bootstrap.min.js"></script>

    <script>

        $("#uploadExcel").click(function (evt) {
            var fileUpload = $("#files").get(0);
            var files = fileUpload.files;
            var data = new FormData();
            for (var i = 0; i < files.length; i++) {
                data.append(files[i].name, files[i]);
            }
            $.ajax({
                type: "POST",
                url: "api/Upload/UploadFilesAjax",
                contentType: false,
                processData: false,
                data: data,
                success: function (message) {
                    //var Msg = eval('(' + message + ')');

                    alert("【Result】:" + message.Result + ";【ImageUrl】:" + message.ImageUrl);
                    1
                },
                error: function () {
                    alert("There was error uploading files!");
                }
            });
        });
    </script>


</body>

</html>