确定上传的文件在MVC上是否为图像（任何格式）

如果它可以帮助任何人，这是HttpPostedFilebase的静态方法，该方法检查给定的上传文件是否为图像：

public static class HttpPostedFilebaseExtensions{    public const int ImageMinimumBytes = 512;    public static bool IsImage(this HttpPostedFilebase postedFile)    {        //-------------------------------------------        //  Check the image mime types        //-------------------------------------------        if (!string.Equals(postedFile.ContentType, "image/jpg", StringComparison.OrdinalIgnoreCase) && !string.Equals(postedFile.ContentType, "image/jpeg", StringComparison.OrdinalIgnoreCase) && !string.Equals(postedFile.ContentType, "image/pjpeg", StringComparison.OrdinalIgnoreCase) && !string.Equals(postedFile.ContentType, "image/gif", StringComparison.OrdinalIgnoreCase) && !string.Equals(postedFile.ContentType, "image/x-png", StringComparison.OrdinalIgnoreCase) && !string.Equals(postedFile.ContentType, "image/png", StringComparison.OrdinalIgnoreCase))        { return false;        }        //-------------------------------------------        //  Check the image extension        //-------------------------------------------        var postedFileExtension = Path.GetExtension(postedFile.FileName);        if (!string.Equals(postedFileExtension , ".jpg", StringComparison.OrdinalIgnoreCase) && !string.Equals(postedFileExtension , ".png", StringComparison.OrdinalIgnoreCase) && !string.Equals(postedFileExtension , ".gif", StringComparison.OrdinalIgnoreCase) && !string.Equals(postedFileExtension , ".jpeg", StringComparison.OrdinalIgnoreCase))        { return false;        }        //-------------------------------------------        //  Attempt to read the file and check the first bytes        //-------------------------------------------        try        { if (!postedFile.InputStream.CanRead) {     return false; } //------------------------------------------ //   Check whether the image size exceeding the limit or not //------------------------------------------  if (postedFile.ContentLength < ImageMinimumBytes) {     return false; } byte[] buffer = new byte[ImageMinimumBytes]; postedFile.InputStream.Read(buffer, 0, ImageMinimumBytes); string content = System.Text.Encoding.UTF8.GetString(buffer); if (Regex.IsMatch(content, @"<script|<html|<head|<title|<body|<pre|<table|<as+href|<img|<plaintext|<cross-domain-policy",     RegexOptions.IgnoreCase | RegexOptions.CultureInvariant | RegexOptions.Multiline)) {     return false; }        }        catch (Exception)        { return false;        }        //-------------------------------------------        //  Try to instantiate new Bitmap, if .NET will throw exception        //  we can assume that it's not a valid image        //-------------------------------------------        try        { using (var bitmap = new System.Drawing.Bitmap(postedFile.InputStream)) { }        }        catch (Exception)        { return false;        }        finally        {  postedFile.InputStream.Position = 0;        }        return true;    }}

编辑2/10/2017：根据建议的编辑，添加了finally语句以重置流，因此我们以后可以使用它。