尽管我在donnetfiddle上为你做了一个示例项目，但大多数答案似乎都足够合理

我正在使用LumenWorks.Framework进行CSV工作，但这不是必须的。

Demo

View

            @using (Html.BeginForm("Index", "Home", "POST")) 

            {
                <div class="form-group">

                        <label for="file">Upload Files:</label>
                        <input type="file" multiple name="files" id="files" class="form-control"/><br><br>
                        <input type="submit" value="Upload Files" class="form-control"/>
                </div>

控制器：

    [HttpPost]
    public ActionResult Index(HttpPostedFileBase upload)
    {
        if (ModelState.IsValid)
        {
            if (upload != null && upload.ContentLength > 0)
            {
                // Validation content length 
                if (upload.FileName.EndsWith(".csv") || upload.FileName.EndsWith(".CSV"))
                {
                    //extention validation 
                    ViewBag.Result = "Correct File Uploaded";
                }
            }
        }

        return View();
    }

提供完整的解决方案

首先在MVC视图中使用.CShtml中的输入

<input type="file" id="UploadImg" /></br>
<img id="imgPreview" height="200" width="200" />

现在调用Ajax调用

  $("#UploadImg").change(function () {
    var data = new FormData();
    var files = $("#UploadImg").get(0).files;
    if (files.length > 0) {
        data.append("MyImages", files[0]);
    }

    $.ajax({
        // url: "Controller/ActionMethod"
        url: "/SignUp/UploadFile",
        type: "POST",
        processData: false,
        contentType: false,
        data: data,
        success: function (response)
        {
            //code after success
            $("#UploadPhoto").val(response);
            $("#imgPreview").attr('src', '/Upload/' + response);
        },
        error: function (er) {
            //alert(er);
        }

    });
});

控制器Json呼叫

[HttpGet]
public JsonResult UploadFile()
    {
        string _imgname = string.Empty;
        if (System.Web.HttpContext.Current.Request.Files.AllKeys.Any())
        {
            var pic = System.Web.HttpContext.Current.Request.Files["MyImages"];
            if (pic.ContentLength > 0)
            {
                var fileName = Path.GetFileName(pic.FileName);
                var _ext = Path.GetExtension(pic.FileName);

                _imgname = Guid.NewGuid().ToString();
                var _comPath = Server.MapPath("/MyFolder") + _imgname + _ext;
                _imgname = "img_" + _imgname + _ext;

                ViewBag.Msg = _comPath;
                var path = _comPath;
                tblAssignment assign = new tblAssignment();
                assign.Uploaded_Path = "/MyFolder" + _imgname + _ext;
                // Saving Image in Original Mode
                pic.SaveAs(path);
            }
        }
        return Json(Convert.ToString(_imgname), JsonRequestBehavior.AllowGet);
    }

我给你简单易懂的方法。

首先，必须在.Cshtml文件中编写以下代码。

<input name="Image" type="file" class="form-control" id="resume" />

然后在控制器中输入以下代码：

if (i > 0) {
    HttpPostedFileBase file = Request.Files["Image"];


    if (file != null && file.ContentLength > 0) {
        if (!string.IsNullOrEmpty(file.FileName)) {
            string extension = Path.GetExtension(file.FileName);

            switch ((extension.ToLower())) {
                case ".doc":
                    break;
                case ".docx":
                    break;
                case ".pdf":
                    break;
                default:
                    ViewBag.result = "Please attach file with extension .doc , .docx , .pdf";
                    return View();
            }

            if (!Directory.Exists(Server.MapPath("~") + "\\Resume\\")) {
                System.IO.Directory.CreateDirectory(Server.MapPath("~") + "\\Resume\\");
            }

            string documentpath = Server.MapPath("~") + "\\Resume\\" + i + "_" + file.FileName;
            file.SaveAs(documentpath);
            string filename = i + "_" + file.FileName;
            result = _objbalResume.UpdateResume(filename, i);
            Attachment at = new Attachment(documentpath);

            //ViewBag.result = (ans == true ? "Thanks for contacting us.We will reply as soon as possible" : "There is some problem. Please try again later.");
        }
    } else {
        ...
    }
}

为此，您必须根据您的数据库制作BAL和DAL层。

在视图中：

<form action="Categories/Upload" enctype="multipart/form-data" method="post">
    <input type="file" name="Image">
    <input type="submit" value="Save">
</form>

而控制器中的以下代码：

public ActionResult Upload()
{
    foreach (string file in Request.Files)
    {
       var hpf = this.Request.Files[file];
       if (hpf.ContentLength == 0)
       {
            continue;
       }

       string savedFileName = Path.Combine(
                AppDomain.CurrentDomain.BaseDirectory, "PutYourUploadDirectoryHere");
                savedFileName = Path.Combine(savedFileName, Path.GetFileName(hpf.FileName));

        hpf.SaveAs(savedFileName);
    }

    ...
}

检查我的解决方案

public string SaveFile(HttpPostedFileBase uploadfile, string saveInDirectory="/", List<string> acceptedExtention =null)
{
    acceptedExtention = acceptedExtention ?? new List<String>() {".png", ".Jpeg"};//optional arguments

    var extension = Path.GetExtension(uploadfile.FileName).ToLower();

    if (!acceptedExtention.Contains(extension))
    {
        throw new UserFriendlyException("Unsupported File type");
    }
    var tempPath = GenerateDocumentPath(uploadfile.FileName, saveInDirectory);
    FileHelper.DeleteIfExists(tempPath);
    uploadfile.SaveAs(tempPath);

    var fileName = Path.GetFileName(tempPath);
    return fileName;
}

private string GenerateDocumentPath(string fileName, string saveInDirectory)
{
    System.IO.Directory.CreateDirectory(Server.MapPath($"~/{saveInDirectory}"));
    return Path.Combine(Server.MapPath($"~/{saveInDirectory}"), Path.GetFileNameWithoutExtension(fileName) +"_"+ DateTime.Now.Ticks + Path.GetExtension(fileName));
}

在基本控制器中添加这些函数，以便可以在所有控制器中使用它们

检查如何使用它

SaveFile(view.PassportPicture,acceptedExtention:new List<String>() { ".png", ".Jpeg"},saveInDirectory: "content/img/PassportPicture");

下面是一个完整的例子

[HttpPost]
public async Task<JsonResult> CreateUserThenGenerateToken(CreateUserViewModel view)
{// CreateUserViewModel contain two properties of type HttpPostedFileBase  
    string passportPicture = null, profilePicture = null;
    if (view.PassportPicture != null)
    {
        passportPicture = SaveFile(view.PassportPicture,acceptedExtention:new List<String>() { ".png", ".Jpeg"},saveInDirectory: "content/img/PassportPicture");
    }
    if (view.ProfilePicture != null)
    {
        profilePicture = SaveFile(yourHttpPostedFileBase, acceptedExtention: new List<String>() { ".png", ".Jpeg" }, saveInDirectory: "content/img/ProfilePicture");
    }
    var input = view.MapTo<CreateUserInput>();
    input.PassportPicture = passportPicture;
    input.ProfilePicture = profilePicture;


    var getUserOutput = await _userAppService.CreateUserThenGenerateToken(input);
    return new AbpJsonResult(getUserOutput);
    //return Json(new AjaxResponse() { Result = getUserOutput, Success = true });

}

另一种传输到字节[]的方法（用于保存到DB）。

@Arthur的方法工作得很好，但不能完美复制，因此MS Office文档在从数据库检索后可能无法打开。MemoryStream.GetBuffer（）可以在字节[]的末尾返回额外的空字节，但可以使用MemoryStream.ToArray（）来解决这个问题。然而，我发现这个替代方案可以完美地适用于所有文件类型：

using (var binaryReader = new BinaryReader(file.InputStream))
{
    byte[] array = binaryReader.ReadBytes(file.ContentLength);
}

这是我的完整代码：

文档类别：

public class Document
{
    public int? DocumentID { get; set; }
    public string FileName { get; set; }
    public byte[] Data { get; set; }
    public string ContentType { get; set; }
    public int? ContentLength { get; set; }

    public Document()
    {
        DocumentID = 0;
        FileName = "New File";
        Data = new byte[] { };
        ContentType = "";
        ContentLength = 0;
    }
}

文件下载：

[HttpGet]
public ActionResult GetDocument(int? documentID)
{
    // Get document from database
    var doc = dataLayer.GetDocument(documentID);

    // Convert to ContentDisposition
    var cd = new System.Net.Mime.ContentDisposition
    {
        FileName = doc.FileName, 

        // Prompt the user for downloading; set to true if you want 
        // the browser to try to show the file 'inline' (display in-browser
        // without prompting to download file).  Set to false if you 
        // want to always prompt them to download the file.
        Inline = true, 
    };
    Response.AppendHeader("Content-Disposition", cd.ToString());

    // View document
    return File(doc.Data, doc.ContentType);
}

文件上载：

[HttpPost]
public ActionResult GetDocument(HttpPostedFileBase file)
{
    // Verify that the user selected a file
    if (file != null && file.ContentLength > 0)
    {
        // Get file info
        var fileName = Path.GetFileName(file.FileName);
        var contentLength = file.ContentLength;
        var contentType = file.ContentType;

        // Get file data
        byte[] data = new byte[] { };
        using (var binaryReader = new BinaryReader(file.InputStream))
        {
            data = binaryReader.ReadBytes(file.ContentLength);
        }

        // Save to database
        Document doc = new Document()
        {
            FileName = fileName,
            Data = data,
            ContentType = contentType,
            ContentLength = contentLength,
        };
        dataLayer.SaveDocument(doc);

        // Show success ...
        return RedirectToAction("Index");
    }
    else
    {
        // Show error ...
        return View("Foo");
    }
}

视图（代码段）：

@using (Html.BeginForm("GetDocument", "Home", FormMethod.Post, new { enctype = "multipart/form-data" }))
{
    <input type="file" name="file" />
    <input type="submit" value="Upload File" />
}