c# 根据文件流查看文件真实格式

今天在做图片注册的功能的时候，测试提出一个问题：将随便一个非图片文件将后缀名改为jpg或其他，上传时应检验图片合法性。然后同事给提供了根据文件流前两个字节判断文件真实格式的思路，代码如下:

  public static FileExtension CheckFileType(string fileName)
        {
            FileStream fs = new FileStream(fileName, FileMode.Open, FileAccess.Read);
            System.IO.BinaryReader br = new System.IO.BinaryReader(fs);
            string fileType = string.Empty; ;
            try
            {
                byte data = br.ReadByte();
                fileType += data.ToString();
                data = br.ReadByte();
                fileType += data.ToString();
                FileExtension extension;
                try
                {
                    extension = (FileExtension)Enum.Parse(typeof(FileExtension), fileType);
                }
                catch 
                { 
                    extension = FileExtension.VALIDFILE;
                }
                return extension;
            }
            catch (Exception ex)
            {
                throw ex;
            }
            finally
            {
                if (fs != null)
                {
                    fs.Close();
                    br.Close();
                }
            }
        }

View Code

public enum FileExtension { JPG = 255216, GIF = 7173, BMP = 6677, PNG = 13780, COM = 7790, EXE = 7790, DLL = 7790, RAR = 8297, ZIP = 8075, XML = 6063, HTML = 6033, ASPX = 239187, CS = 117115, JS = 119105, TXT = 210187, SQL = 255254, BAT = 64101, BTSEED = 10056, RDP = 255254, PSD = 5666, PDF = 3780, CHM = 7384, LOG = 70105, REG = 8269, HLP = 6395, DOC = 208207, XLS = 208207, DOCX = 208207, XLSX = 208207, VALIDFILE = 9999999 }

但是此方法不可以用于判断视频格式，不知走过路过的有木有较好的解决方案。

c# 根据文件流查看文件真实格式

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