EPPlus 已經支持 .net core 了

https://www.nuget.org/packages/EPPlus

https://github.com/JanKallman/EPPlus

寫入 excel

public async Task<IActionResult> About()
{
ViewData["Message"] = "Your application description page.";
var products = new List<Product>
{
    new Product
    {
        name = "mk100",
        date 
 
= DateTime.Now,
        amount = 99.33,
        published = false,
        sort = 1
    },
    new Product
    {
        name = "mk200",
        date = DateTime.Now,
        amount = 99.33,
        published = true,
        sort = 2
    }
};

byte[] responseBytes;
string path = Path.Combine(HostingEnvironment.WebRootPath, "
 
excel", "abc.xlsx");
using (var package = new ExcelPackage())
{
    // Add a new worksheet to the empty workbook
    ExcelWorksheet worksheet = package.Workbook.Worksheets.Add("Inventory");
    // 2 種方式做 select 
    // - 從新創建想要的對象 (比較靈活)
    // - 通過 memberInfoes 選出要的 
    //var memberInfoes = "name,date,amount,published,sort".Split(‘,‘).Select(v => typeof(Product).GetProperty(v)).ToArray();
 

    var datas = products.Select(p => new
    {
        p.name,
        p.date
    });
                
    worksheet.Cells["A1"].LoadFromCollection(
        datas,
        true,
        TableStyles.None
        //BindingFlags.Public,
        //memberInfoes
    );

    // 弄 date/datetime format 
    using (var cellRanges = worksheet.Cells[$"B2:B{datas.Count() + 1}"])
    {
        cellRanges.Style.Numberformat.Format = "yyyy-mm-dd";
    }
                
    //Add the headers
    //worksheet.Cells[1, 1].Value = "String";
    //worksheet.Cells[1, 2].Value = "Int";
    //worksheet.Cells[1, 3].Value = "Double";
    //worksheet.Cells[1, 4].Value = "Boolean";
    //worksheet.Cells[1, 5].Value = "Date";

    //worksheet.Cells[2, 1].Value = "dasd";
    //worksheet.Cells[2, 2].Value = 12312;
    //worksheet.Cells[2, 3].Value = 123.123123;
    //worksheet.Cells[2, 4].Value = true;
    //worksheet.Cells[2, 5].Value = DateTime.Now;
    //worksheet.Cells[2, 5].Style.Numberformat.Format = "yyyy-mm-dd";

    //worksheet.Cells["C2:C5"].Style.Numberformat.Format = "#,##0";
    //worksheet.Cells["D2:E5"].Style.Numberformat.Format = "#,##0.00";

    worksheet.Cells.AutoFitColumns(0);  //Autofit columns for all cells
    System.IO.File.Delete(path);

    // note  package.SaveAs 和 package.GetAsByteArray() 不能一起用
    // 用了一個另一個就不能用了，通常我們是選其中一個用而已啦，很少 2 個都需要的 
    // 解決方法很簡單，用 byte 然後 file stream 寫 bytes 進去 

    responseBytes = package.GetAsByteArray();
    using (var fs = System.IO.File.Create(path))
    {
        await fs.WriteAsync(responseBytes);
        //package.SaveAs(fs);
    }              
}

//return File(responseBytes, "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet", "report.xlsx");

return File(await System.IO.File.ReadAllBytesAsync(path), "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet", "report.xlsx");
}

讀 excel

public IActionResult Contact()
{
    var path = Path.Combine(HostingEnvironment.WebRootPath, "excel", "abc.xlsx");
    using (var fs = System.IO.File.Open(path, FileMode.Open, FileAccess.Read))
    using (var package = new ExcelPackage(fs))
    {
        var worksheet = package.Workbook.Worksheets["Inventory"];

        var sc = worksheet.Dimension.Start.Column;
        var ec = worksheet.Dimension.End.Column;
        var sr = worksheet.Dimension.Start.Row;
        var er = worksheet.Dimension.End.Row;
        var value = worksheet.Cells[sc, sr + 1].Value;
    }
             

    ViewData["Message"] = "Your contact page.";

    return View();
}

Asp.net core 學習筆記 (Excel 讀寫)