我在做文件上传概念时也遇到过同样的错误。我知道开发人员为这个问题提供了很多答案。

尽管我回答这个问题的原因是，由于下面提到的疏忽错误，我犯了这个错误。

<input type="file" name="uploadedFile" />

在指定name属性时，请确保控制器参数也具有相同的名称值“uploadedFile”。这样地：

   [HttpPost]
            public ActionResult FileUpload(HttpPostedFileBase uploadedFile)
            {

            }

否则它不会被映射。

MemoryStream.GetBuffer() can return extra empty bytes at the end of the byte[], but you can fix that by using MemoryStream.ToArray() instead. However, I found this alternative to work perfectly for all file types:

using (var binaryReader = new BinaryReader(file.InputStream))
{
    byte[] array = binaryReader.ReadBytes(file.ContentLength);
}
Here's my full code:

Document Class:

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;
    }
}
File Download:

[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);
}
File Upload:

[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");
    }
}
View (snippet):

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

保存多个文件的简单方法

cshtml

@using (Html.BeginForm("Index","Home",FormMethod.Post,new { enctype = "multipart/form-data" }))
{
    <label for="file">Upload Files:</label>
    <input type="file" multiple name="files" id="files" /><br><br>
    <input type="submit" value="Upload Files" />
    <br><br>
    @ViewBag.Message
}

控制器

[HttpPost]
        public ActionResult Index(HttpPostedFileBase[] files)
        {
            foreach (HttpPostedFileBase file in files)
            {
                if (file != null && file.ContentLength > 0)
                    try
                    {
                        string path = Path.Combine(Server.MapPath("~/Files"), Path.GetFileName(file.FileName));
                        file.SaveAs(path);
                        ViewBag.Message = "File uploaded successfully";
                    }
                    catch (Exception ex)
                    {
                        ViewBag.Message = "ERROR:" + ex.Message.ToString();
                    }

                else
                {
                    ViewBag.Message = "You have not specified a file.";
                }
            }
            return View();
        }

由于我在IE浏览器中发现了上传文件的问题，我建议这样处理。

View

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

控制器

public class HomeController : Controller
{
    public ActionResult UploadFile()
    {
        return View();
    }

    [HttpPost]
    public ActionResult UploadFile(MyModal Modal)
    {
            string DocumentName = string.Empty;
            string Description = string.Empty;

            if (!String.IsNullOrEmpty(Request.Form["DocumentName"].ToString()))
                DocumentName = Request.Form["DocumentName"].ToString();
            if (!String.IsNullOrEmpty(Request.Form["Description"].ToString()))
                Description = Request.Form["Description"].ToString();

            if (!String.IsNullOrEmpty(Request.Form["FileName"].ToString()))
                UploadedDocument = Request.Form["FileName"].ToString();

            HttpFileCollectionBase files = Request.Files;

            string filePath = Server.MapPath("~/Root/Documents/");
            if (!(Directory.Exists(filePath)))
                Directory.CreateDirectory(filePath);
            for (int i = 0; i < files.Count; i++)
            {
                HttpPostedFileBase file = files[i];
                // Checking for Internet Explorer  
                if (Request.Browser.Browser.ToUpper() == "IE" || Request.Browser.Browser.ToUpper() == "INTERNETEXPLORER")
                {
                    string[] testfiles = file.FileName.Split(new char[] { '\\' });
                    fname = testfiles[testfiles.Length - 1];
                    UploadedDocument = fname;
                }
                else
                {
                    fname = file.FileName;
                    UploadedDocument = file.FileName;
                }
                file.SaveAs(fname);
                return RedirectToAction("List", "Home");
}

我的方法和上面差不多，我将向您展示我的代码以及如何使用MYSSQL数据库。。。

数据库中的文档表-

int Id（PK），字符串Url，字符串描述，创建者，租户ID上传日期

上面的代码ID是主键，URL是文件的名称（末尾有文件类型），要在文档视图中输出的文件描述，CreatedBy是上载文件的人，tenncyId，dateUploaded

在视图中，必须定义enctype，否则它将无法正常工作。

@using (Html.BeginForm("Upload", "Document", FormMethod.Post, new { enctype = "multipart/form-data" }))
{
<div class="input-group">
    <label for="file">Upload a document:</label>
    <input type="file" name="file" id="file" />
</div>
}

上面的代码将给你一个浏览按钮，然后在我的项目中，我有一个基本上名为IsValidImage的类，它只是检查文件大小是否在指定的最大大小之下，检查它是否是IMG文件，这都在类bool函数中。所以，如果true返回true。

public static bool IsValidImage(HttpPostedFileBase file, double maxFileSize, ModelState ms )
{
    // make sur the file isnt null.
    if( file == null )
        return false;

// the param I normally set maxFileSize is 10MB  10 * 1024 * 1024 = 10485760 bytes converted is 10mb
var max = maxFileSize * 1024 * 1024;

// check if the filesize is above our defined MAX size.
if( file.ContentLength > max )
    return false;

try
{
    // define our allowed image formats
    var allowedFormats = new[] { ImageFormat.Jpeg, ImageFormat.Png, ImageFormat.Gif, ImageFormat.Bmp };

    // Creates an Image from the specified data stream.      
    using (var img = Image.FromStream(file.InputStream))
    {
        // Return true if the image format is allowed
        return allowedFormats.Contains(img.RawFormat);
    }
}
catch( Exception ex )
{
    ms.AddModelError( "", ex.Message );                 
}
return false;   
}

因此，在控制器中：

if (!Code.Picture.IsValidUpload(model.File, 10, true))
{                
    return View(model);
}

// Set the file name up... Being random guid, and then todays time in ticks. Then add the file extension
// to the end of the file name
var dbPath = Guid.NewGuid().ToString() + DateTime.UtcNow.Ticks + Path.GetExtension(model.File.FileName);

// Combine the two paths together being the location on the server to store it
// then the actual file name and extension.
var path = Path.Combine(Server.MapPath("~/Uploads/Documents/"), dbPath);

// set variable as Parent directory I do this to make sure the path exists if not
// I will create the directory.
var directoryInfo = new FileInfo(path).Directory;

if (directoryInfo != null)
    directoryInfo.Create();

// save the document in the combined path.
model.File.SaveAs(path);

// then add the data to the database
_db.Documents.Add(new Document
{
    TenancyId = model.SelectedTenancy,
    FileUrl = dbPath,
    FileDescription = model.Description,
    CreatedBy = loggedInAs,
    CreatedDate = DateTime.UtcNow,
    UpdatedDate = null,
    CanTenantView = true
});

_db.SaveChanges();
model.Successfull = 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" />
}