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();
    }

如果你碰巧像我一样在这里跌跌撞撞，想知道尽管代码正确，为什么你的代码仍然不工作。然后，请在输入控件中查找name属性，您可能会意外错过或从未将其放在首位。

<input class="custom-file-input" name="UploadFile" id="UploadFile" type="file" onchange="ValidateFile(this);" accept=".xls, .xlsx">
                             

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;

您不使用文件输入控件。ASP.NET MVC中未使用服务器端控件。查看下面的博客文章，其中说明了如何在ASP.NET MVC中实现这一点。

因此，您将首先创建一个HTML表单，其中包含文件输入：

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

然后你会有一个控制器来处理上传：

public class HomeController : Controller
{
    // This action renders the form
    public ActionResult Index()
    {
        return View();
    }

    // This action handles the form POST and the upload
    [HttpPost]
    public ActionResult Index(HttpPostedFileBase file)
    {
        // Verify that the user selected a file
        if (file != null && file.ContentLength > 0) 
        {
            // extract only the filename
            var fileName = Path.GetFileName(file.FileName);
            // store the file inside ~/App_Data/uploads folder
            var path = Path.Combine(Server.MapPath("~/App_Data/uploads"), fileName);
            file.SaveAs(path);
        }
        // redirect back to the index action to show the form once again
        return RedirectToAction("Index");        
    }
}

如果有人想用Ajax上传多个文件，下面是我的文章在Asp.NetMVC中使用Ajax进行多文件上传

要传输到字节[]（例如，用于保存到DB）：

using (MemoryStream ms = new MemoryStream()) {
    file.InputStream.CopyTo(ms);
    byte[] array = ms.GetBuffer();
}

若要将输入流直接传输到数据库中，而不将其存储在内存中，您可以使用从此处获取的此类，并稍作更改：

public class VarbinaryStream : Stream {
private SqlConnection _Connection;

private string _TableName;
private string _BinaryColumn;
private string _KeyColumn;
private int _KeyValue;

private long _Offset;

private SqlDataReader _SQLReader;
private long _SQLReadPosition;

private bool _AllowedToRead = false;

public VarbinaryStream(
    string ConnectionString,
    string TableName,
    string BinaryColumn,
    string KeyColumn,
    int KeyValue,
    bool AllowRead = false)
{
  // create own connection with the connection string.
  _Connection = new SqlConnection(ConnectionString);

  _TableName = TableName;
  _BinaryColumn = BinaryColumn;
  _KeyColumn = KeyColumn;
  _KeyValue = KeyValue;


  // only query the database for a result if we are going to be reading, otherwise skip.
  _AllowedToRead = AllowRead;
  if (_AllowedToRead == true)
  {
    try
    {
      if (_Connection.State != ConnectionState.Open)
        _Connection.Open();

      SqlCommand cmd = new SqlCommand(
                      @"SELECT TOP 1 [" + _BinaryColumn + @"]
                            FROM [dbo].[" + _TableName + @"]
                            WHERE [" + _KeyColumn + "] = @id",
                  _Connection);

      cmd.Parameters.Add(new SqlParameter("@id", _KeyValue));

      _SQLReader = cmd.ExecuteReader(
          CommandBehavior.SequentialAccess |
          CommandBehavior.SingleResult |
          CommandBehavior.SingleRow |
          CommandBehavior.CloseConnection);

      _SQLReader.Read();
    }
    catch (Exception e)
    {
      // log errors here
    }
  }
}

// this method will be called as part of the Stream ímplementation when we try to write to our VarbinaryStream class.
public override void Write(byte[] buffer, int index, int count)
{
  try
  {
    if (_Connection.State != ConnectionState.Open)
      _Connection.Open();

    if (_Offset == 0)
    {
      // for the first write we just send the bytes to the Column
      SqlCommand cmd = new SqlCommand(
                                  @"UPDATE [dbo].[" + _TableName + @"]
                                            SET [" + _BinaryColumn + @"] = @firstchunk 
                                        WHERE [" + _KeyColumn + "] = @id",
                              _Connection);

      cmd.Parameters.Add(new SqlParameter("@firstchunk", buffer));
      cmd.Parameters.Add(new SqlParameter("@id", _KeyValue));

      cmd.ExecuteNonQuery();

      _Offset = count;
    }
    else
    {
      // for all updates after the first one we use the TSQL command .WRITE() to append the data in the database
      SqlCommand cmd = new SqlCommand(
                              @"UPDATE [dbo].[" + _TableName + @"]
                                        SET [" + _BinaryColumn + @"].WRITE(@chunk, NULL, @length)
                                    WHERE [" + _KeyColumn + "] = @id",
                           _Connection);

      cmd.Parameters.Add(new SqlParameter("@chunk", buffer));
      cmd.Parameters.Add(new SqlParameter("@length", count));
      cmd.Parameters.Add(new SqlParameter("@id", _KeyValue));

      cmd.ExecuteNonQuery();

      _Offset += count;
    }
  }
  catch (Exception e)
  {
    // log errors here
  }
}

// this method will be called as part of the Stream ímplementation when we try to read from our VarbinaryStream class.
public override int Read(byte[] buffer, int offset, int count)
{
  try
  {
    long bytesRead = _SQLReader.GetBytes(0, _SQLReadPosition, buffer, offset, count);
    _SQLReadPosition += bytesRead;
    return (int)bytesRead;
  }
  catch (Exception e)
  {
    // log errors here
  }
  return -1;
}
public override bool CanRead
{
  get { return _AllowedToRead; }
}

protected override void Dispose(bool disposing)
{
  if (_Connection != null)
  {
    if (_Connection.State != ConnectionState.Closed)
      try { _Connection.Close();           }
      catch { }
    _Connection.Dispose();
  }
  base.Dispose(disposing);
}

#region unimplemented methods
public override bool CanSeek
{
  get { return false; }
}

public override bool CanWrite
{
  get { return true; }
}

public override void Flush()
{
  throw new NotImplementedException();
}

public override long Length
{
  get { throw new NotImplementedException(); }
}

public override long Position
{
  get
  {
    throw new NotImplementedException();
  }
  set
  {
    throw new NotImplementedException();
  }
}
public override long Seek(long offset, SeekOrigin origin)
{
  throw new NotImplementedException();
}

public override void SetLength(long value)
{
  throw new NotImplementedException();
}
#endregion unimplemented methods  }

以及用法：

  using (var filestream = new VarbinaryStream(
                            "Connection_String",
                            "Table_Name",
                            "Varbinary_Column_name",
                            "Key_Column_Name",
                            keyValueId,
                            true))
  {
    postedFile.InputStream.CopyTo(filestream);
  }