如何显示要从MVC控制器下载的文件？

在WebForms中，我通常会使用如下代码，以使浏览器显示“下载文件”弹出窗口，其中包含任意文件类型（例如PDF）和文件名：

Response.Clear()
Response.ClearHeaders()
''# Send the file to the output stream
Response.Buffer = True

Response.AddHeader("Content-Length", pdfData.Length.ToString())
Response.AddHeader("Content-Disposition", "attachment; filename= " & Server.HtmlEncode(filename))

''# Set the output stream to the correct content type (PDF).
Response.ContentType = "application/pdf"

''# Output the file
Response.BinaryWrite(pdfData)

''# Flushing the Response to display the serialized data
''# to the client browser.
Response.Flush()
Response.End()

如何在ASP.NET MVC中完成相同的任务？

根据您的操作是否返回a FileResult或FileStreamResult，取决于文件是否存在或您即时创建文件。

public ActionResult GetPdf(string filename)
{
    return File(filename, "application/pdf", Server.UrlEncode(filename));
}

要强制下载PDF文件，而不是由浏览器的PDF插件处理：

public ActionResult DownloadPDF()
{
    return File("~/Content/MyFile.pdf", "application/pdf", "MyRenamedFile.pdf");
}

如果要让浏览器以默认行为（插件或下载）处理，只需发送两个参数即可。

public ActionResult DownloadPDF()
{
    return File("~/Content/MyFile.pdf", "application/pdf");
}

您需要使用第三个参数在浏览器对话框上为文件指定名称。

更新：Charlino是正确的，当传递第三个参数（下载文件名）时，会将其Content-Disposition: attachment;添加到Http响应标头中。我的解决方案是以application\force-downloadmime-type的形式发送，但这会导致下载文件名出现问题，因此需要第三个参数来发送良好的文件名，因此无需强制执行下载。

您可以在Razor或Controller中执行相同的操作。

@{
    //do this on the top most of your View, immediately after `using` statement
    Response.ContentType = "application/pdf";
    Response.AddHeader("Content-Disposition", "attachment; filename=receipt.pdf");
}

或在控制器中。

public ActionResult Receipt() {
    Response.ContentType = "application/pdf";
    Response.AddHeader("Content-Disposition", "attachment; filename=receipt.pdf");

    return View();
}

我在Chrome和IE9中都尝试过，两者都在下载pdf文件。

我可能应该补充一点，我正在使用RazorPDF生成我的PDF。这是关于它的博客：http : //nyveldt.com/blog/post/Introducing-RazorPDF

您应该查看Controller的File方法。这正是它的目的。它返回FilePathResult而不是ActionResult。

镁诺南

您可以执行以下操作以返回FileStream：

/// <summary>
/// Creates a new Excel spreadsheet based on a template using the NPOI library.
/// The template is changed in memory and a copy of it is sent to
/// the user computer through a file stream.
/// </summary>
/// <returns>Excel report</returns>
[AcceptVerbs(HttpVerbs.Post)]
public ActionResult NPOICreate()
{
    try
    {
        // Opening the Excel template...
        FileStream fs =
            new FileStream(Server.MapPath(@"\Content\NPOITemplate.xls"), FileMode.Open, FileAccess.Read);

        // Getting the complete workbook...
        HSSFWorkbook templateWorkbook = new HSSFWorkbook(fs, true);

        // Getting the worksheet by its name...
        HSSFSheet sheet = templateWorkbook.GetSheet("Sheet1");

        // Getting the row... 0 is the first row.
        HSSFRow dataRow = sheet.GetRow(4);

        // Setting the value 77 at row 5 column 1
        dataRow.GetCell(0).SetCellValue(77);

        // Forcing formula recalculation...
        sheet.ForceFormulaRecalculation = true;

        MemoryStream ms = new MemoryStream();

        // Writing the workbook content to the FileStream...
        templateWorkbook.Write(ms);

        TempData["Message"] = "Excel report created successfully!";

        // Sending the server processed data back to the user computer...
        return File(ms.ToArray(), "application/vnd.ms-excel", "NPOINewFile.xls");
    }
    catch(Exception ex)
    {
        TempData["Message"] = "Oops! Something went wrong.";

        return RedirectToAction("NPOI");
    }
}

尽管可以将标准操作结果FileContentResult或FileStreamResult用于下载文件，但为了可重用，创建自定义操作结果可能是最好的解决方案。

作为示例，让我们创建一个自定义操作结果，以将数据即时导出到Excel文件进​​行下载。

ExcelResult类继承抽象的ActionResult类，并重写ExecuteResult方法。

我们正在使用FastMember包从IEnumerable对象创建DataTable，并使用ClosedXML包从DataTable创建Excel文件。

public class ExcelResult<T> : ActionResult
{
    private DataTable dataTable;
    private string fileName;

    public ExcelResult(IEnumerable<T> data, string filename, string[] columns)
    {
        this.dataTable = new DataTable();
        using (var reader = ObjectReader.Create(data, columns))
        {
            dataTable.Load(reader);
        }
        this.fileName = filename;
    }

    public override void ExecuteResult(ControllerContext context)
    {
        if (context != null)
        {
            var response = context.HttpContext.Response;
            response.Clear();
            response.ContentType = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet";
            response.AddHeader("content-disposition", string.Format(@"attachment;filename=""{0}""", fileName));
            using (XLWorkbook wb = new XLWorkbook())
            {
                wb.Worksheets.Add(dataTable, "Sheet1");
                using (MemoryStream stream = new MemoryStream())
                {
                    wb.SaveAs(stream);
                    response.BinaryWrite(stream.ToArray());
                }
            }
        }
    }
}

在Controller中，使用自定义ExcelResult操作结果，如下所示

[HttpGet]
public async Task<ExcelResult<MyViewModel>> ExportToExcel()
{
    var model = new Models.MyDataModel();
    var items = await model.GetItems();
    string[] columns = new string[] { "Column1", "Column2", "Column3" };
    string filename = "mydata.xlsx";
    return new ExcelResult<MyViewModel>(items, filename, columns);
}

由于我们使用HttpGet下载文件，因此创建一个没有模型和布局的空视图。

有关下载动态创建的文件的自定义操作结果的博客文章：

https://acanozturk.blogspot.com/2019/03/custom-actionresult-for-files-in-aspnet.html

使用.ashx文件类型并使用相同的代码