CoreProgramm

<form asp-controller="Home" asp-action="Export">
    <div class="container">
        <div class="row">
            <div class="col-md-4">
                <input type="file" id="fileupload" name="files" class="form-control" />
            </div>
            <div class="col-md-3">
                <input type="button" name="Upload" value="Upload" id="btnupload" class="btn btn-primary" />
                <a href="@Url.Action("Download", "Home")">Download</a>
            </div>

CoreProgramm

<script type="text/javascript" src="https://code.jquery.com/jquery-3.4.1.min.js"></script>
<script type="text/javascript">
    $(function () {
        $('#btnupload').on('click', function () {
            var fileExtension = ['xls', 'xlsx'];
            var filename = $('#fileupload').val();
            if (filename.length == 0) {
                alert("Please select a file.");
                return false;
            }

CoreProgramm

public ActionResult Import()
        {
            IFormFile file = Request.Form.Files[0];
            string folderName = "UploadExcel";
            string webRootPath = _hostingEnvironment.WebRootPath;
            string newPath = Path.Combine(webRootPath, folderName);
            StringBuilder sb = new StringBuilder();
            if (!Directory.Exists(newPath))
            {
                Directory.CreateDirectory(newPath);

CoreProgramm

public ActionResult Download()
        {
            string Files = "wwwroot/UploadExcel/CoreProgramm_ExcelImport.xlsx";
            byte[] fileBytes = System.IO.File.ReadAllBytes(Files);
            System.IO.File.WriteAllBytes(Files, fileBytes);
            MemoryStream ms = new MemoryStream(fileBytes);
            return File(fileBytes, System.Net.Mime.MediaTypeNames.Application.Octet, "employee.xlsx");
        }

CoreProgramm

public async Task<IActionResult> Export()
        {
            string sWebRootFolder = _hostingEnvironment.WebRootPath;
            string sFileName = @"Employees.xlsx";
            string URL = string.Format("{0}://{1}/{2}", Request.Scheme, Request.Host, sFileName);
            FileInfo file = new FileInfo(Path.Combine(sWebRootFolder, sFileName));
            var memory = new MemoryStream();
            using (var fs = new FileStream(Path.Combine(sWebRootFolder, sFileName), FileMode.Create, FileAccess.Write))
            {
                IWorkbook workbook;

CoreProgramm

public class HomeController : Controller
    {
        private readonly IHostingEnvironment _hostingEnv = null;
        string AppBasePath = null;
        string ContentRootPath = null;
        public HomeController(IHostingEnvironment HostingEnv)
        {
            _hostingEnv = HostingEnv;
            AppBasePath = _hostingEnv.WebRootPath;  //path to wwwroot
            ContentRootPath = _hostingEnv.ContentRootPath; //path to GetBasePath

CoreProgramm

public Startup(IConfiguration configuration,IHostingEnvironment _env)
   {
     Configuration = configuration;
     string sAppPath = _env.ContentRootPath; //Application Base Path
     string swwwRootPath = _env.WebRootPath;  //wwwroot folder path
    }

CoreProgramm

{
  "mailConfig": {
    "mailFrom": "info@coreprogramm.com",
    "host": "smtp.google.com",
    "portNo": "465",
    "password": "CorePa$$word"
  }
}

CoreProgramm

public class MailConfig
  {
    public string mailFrom { get; set; }
    public string host { get; set; }
    public string password { get; set; }
    public int portNo { get; set; }
  }

CoreProgramm

 public void ConfigureServices(IServiceCollection services)
        {
            services.Configure<MailConfig>(Configuration.GetSection("mailConfig"));
            services.AddControllersWithViews();
        }