c# - 为用户创建头像上传表单

Question

我正在使用 ASP.Net MVC 5，我想为我的用户配置文件创建一个头像。我不确定我目前所做的是否正确，尤其是出于安全原因，所以我想获得一些建议。

目前我在做什么

在 View 中:

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

在 Controller 中:

    internal static bool SaveAvatar(User user, HttpPostedFileBase file)
    {
        if (file == null || file.ContentLength <= 0 || file.ContentLength > MAX_LENGTH)
            return false;

        //I think I should convert the file somehow instead of saving it
        var path = HostingEnvironment.MapPath("~/img/avatar/") + string.Format("{0}.png", user.UserName);
        file.SaveAs(path);
        user.HasAvatar = true;

        return true;
    }

我有几个问题:

• 在上面的代码中，正如我评论的那样，我认为不仅仅是保存用户发送给我的内容，我应该以某种方式使用库来转换将图像转换为 PNG 文件并保存。如果是这样，是否有一个好的和简单的库来执行此操作？
• 我想知道使用用户名作为文件是否是个好主意。毕竟，这个名字是他们选择的，不是我能决定的。
• 使用纯图像是个好主意还是我应该创建一个 Controller 来验证请求或将请求发送到隐藏图像？

如果我正在做的事情完全是错误的，而您知道更好的资源来学习正确的方法，请为我​​指出正确的方向。谢谢。

Answer 1

您可以使用此类将文件上传到服务器:

public static class FileUpload
{
        public static char DirSeparator = System.IO.Path.DirectorySeparatorChar;
        public static string FilesPath = HttpContext.Current.Server.MapPath("~\\Content" + DirSeparator + "Uploads" + DirSeparator);

        public static string UploadFile(HttpPostedFileBase file)
        {
            // Check if we have a file
            if (null == file) return "";
            // Make sure the file has content
            if (!(file.ContentLength > 0)) return "";

            string fileName =DateTime.Now.Millisecond+ file.FileName;
            string fileExt = Path.GetExtension(file.FileName);

            // Make sure we were able to determine a proper extension
            if (null == fileExt) return "";

            // Check if the directory we are saving to exists
            if (!Directory.Exists(FilesPath))
            {
                // If it doesn't exist, create the directory
                Directory.CreateDirectory(FilesPath);
            }

            // Set our full path for saving
            string path = FilesPath + DirSeparator + fileName;

            // Save our file
            file.SaveAs(Path.GetFullPath(path));

            // Save our thumbnail as well
            ResizeImage(file, 70, 70);

            // Return the filename
            return fileName;
        }

        public static void DeleteFile(string fileName)
        {
            // Don't do anything if there is no name
            if (fileName.Length == 0) return;

            // Set our full path for deleting
            string path = FilesPath + DirSeparator + fileName;
            string thumbPath = FilesPath + DirSeparator + "Thumbnails" + DirSeparator + fileName;

            RemoveFile(path);
            RemoveFile(thumbPath);
        }

        private static void RemoveFile(string path)
        {
            // Check if our file exists
            if (File.Exists(Path.GetFullPath(path)))
            {
                // Delete our file
                File.Delete(Path.GetFullPath(path));
            }
        }

        public static void ResizeImage(HttpPostedFileBase file, int width, int height)
        {
            string thumbnailDirectory = String.Format(@"{0}{1}{2}", FilesPath, DirSeparator, "Thumbnails");

            // Check if the directory we are saving to exists
            if (!Directory.Exists(thumbnailDirectory))
            {
                // If it doesn't exist, create the directory
                Directory.CreateDirectory(thumbnailDirectory);
            }

            // Final path we will save our thumbnail
            string imagePath = String.Format(@"{0}{1}{2}", thumbnailDirectory, DirSeparator, file.FileName);
            // Create a stream to save the file to when we're done resizing
            FileStream stream = new FileStream(Path.GetFullPath(imagePath), FileMode.OpenOrCreate);

            // Convert our uploaded file to an image
            Image OrigImage = Image.FromStream(file.InputStream);
            // Create a new bitmap with the size of our thumbnail
            Bitmap TempBitmap = new Bitmap(width, height);

            // Create a new image that contains are quality information
            Graphics NewImage = Graphics.FromImage(TempBitmap);
            NewImage.CompositingQuality = CompositingQuality.HighQuality;
            NewImage.SmoothingMode = SmoothingMode.HighQuality;
            NewImage.InterpolationMode = InterpolationMode.HighQualityBicubic;

            // Create a rectangle and draw the image
            Rectangle imageRectangle = new Rectangle(0, 0, width, height);
            NewImage.DrawImage(OrigImage, imageRectangle);

            // Save the final file
            TempBitmap.Save(stream, OrigImage.RawFormat);

            // Clean up the resources
            NewImage.Dispose();
            TempBitmap.Dispose();
            OrigImage.Dispose();
            stream.Close();
            stream.Dispose();
        }

您还可以使用 ResizeImage 方法保存他们照片的缩略图，在 Controller 中，我将以这种方式将文件名保存在数据库中:

[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult Create(User user, HttpPostedFileBase file)
{

                // TODO: Add insert logic here
            user.Pictuer = FileUpload.UploadFile(file);
                    db.User.Add(user);
                    db.SaveChanges();
                    return RedirectToAction("Index");


 }

还可以使用 this code 转换上传的图像在 UploadFile 方法中:

    System.Drawing.Image image1 = System.Drawing.Image.FromFile(@"C:\test.bmp");
// Save the image in JPEG format.
        image1.Save(@"C:\test.jpg", System.Drawing.Imaging.ImageFormat.Jpeg);

        // Save the image in GIF format.
        image1.Save(@"C:\test.gif", System.Drawing.Imaging.ImageFormat.Gif);

        // Save the image in PNG format.
        image1.Save(@"C:\test.png", System.Drawing.Imaging.ImageFormat.Png);