一个检测文件类型的辅助类(FileUtitity)_项目管理_非技术区_程序员俱乐部

这是去年一个WPF项目中写的一个用于识别文件类型的辅助类，主要用于检测一些常用的文件格式吗

注意: 该类已经在实际的产品被运用，但是作者依然不能保证该辅助类在实际文件中的检测百分百的正确，使用过程请谨慎!

1. 图像: jpg,bmp,png,jpeg,gif等

2. 视频: MP4,AVI,RMVB,FLV,SWF,RM,WMV

3. 音频:MP3,WMA,WAV,MID,MIDI

    /// <summary>
    /// 文件类型
    /// </summary>
    public enum ResourceType {
        /// <summary>
        /// 图片资源
        /// </summary>
        Image,

        /// <summary>
        /// 视频资源
        /// </summary>
        Video,

        /// <summary>
        /// 音频资源
        /// </summary>
        Audio,

        /// <summary>
        /// 动画资源
        /// </summary>
        Flash,

        /// <summary>
        /// 未知
        /// </summary>
        Unknown
    }

    /// <summary>
    /// 文件类型识别辅助类</ BY andy1987 />
    /// </summary>
    public static class FileUtility {
        #region 静态变量
        private static List<string> IMAGE_EXTENSIONS = new List<string>
        { 
            ".GIF",".PNG",".BMP",".TIFF",".WMF",".EMP",".ICO",".JPG",".JPEG"
        };

        private static List<string> VIDEO_EXTENSION = new List<string> 
        {
            ".MP4",".AVI",".RMVB",".FLV",".SWF",".RM",".WMV"
        };

        private static List<string> AUDIO_EXTENSION = new List<string> 
        {
            ".MP3",".WMA",".WAV",".MID",".MIDI"
        };
        #endregion
        #region 图片
        public static ImageType GetImageType(System.IO.Stream stream) {
            //从文件流中读取前8个字节，然后根据各种图片资源magic number
            //比较确定图片文件格式
            byte[] header = new byte[8];
            stream.Seek(0, SeekOrigin.Begin);
            if (stream.Read(header, 0, header.Length) != header.Length)
                return ImageType.UNKNOWN;

            //BMP
            string bmpHeader = Encoding.ASCII.GetString(header, 0, 2);
            if (bmpHeader == "BM")// window 平台下BMP图片标识，OS/2下图片标识可能为BA,CI,IC等
                return ImageType.BMP;
            else if (bmpHeader == "BA")   //BA= Bitmap array
                return ImageType.BMP;
            else if (bmpHeader == "CI")     //CI= Color Icon
                return ImageType.BMP;
            else if (bmpHeader == "CP")   //CP= Color Pointer
                return ImageType.BMP;
            else if (bmpHeader == "IC")     //IC= Icon
                return ImageType.BMP;
            else if (bmpHeader == "PT")   //PI= Pointer
                return ImageType.BMP;

            //TIFF
            string tiffHeader = Encoding.ASCII.GetString(header, 0, 4);
            if (tiffHeader == "MM\x00\x2a") //大端模式下，TIFF前4个字节数据
                return ImageType.TIFF;
            else if (tiffHeader == "II\x2a\x00") // 小端模式下，TIFF前4个字节数据
                return ImageType.TIFF;

            //PNG
            if (header[0] == 0x89 && header[1] == 0x50 && header[2] == 0x4E && header[3] == 0x47 &&
                header[4] == 0x0D && header[5] == 0x0A && header[6] == 0x1A && header[7] == 0x0A)
                return ImageType.PNG;

            // GIF
            string gifHeader = Encoding.ASCII.GetString(header, 0, 4);
            if (gifHeader == "GIF8")
                return ImageType.GIF;

            // JPEG
            if (header[0] == 0xFF && header[1] == 0xD8)
                return ImageType.JPG;

            // WMF
            if (header[0] == 0xD7 && header[1] == 0xCD && header[2] == 0xC6 && header[3] == 0x9A)
                return ImageType.WMF;

            // EMF
            if (header[0] == 0x01 && header[1] == 0x00 && header[2] == 0x00 && header[3] == 0x00)
                return ImageType.EMF;

            // Windows Icons
            if (header[0] == 0x00 && header[1] == 0x00 && header[2] == 0x01 && header[3] == 0x00) // ICO
                return ImageType.ICON;
            else if (header[0] == 0x00 && header[1] == 0x00 && header[2] == 0x02 && header[3] == 0x00) // CUR
                return ImageType.ICON;

            return ImageType.UNKNOWN;
        }

        /// <summary>
        /// 判断图片文件类型，通过指定的图片路径
        /// ps:判断结果最终由文件后缀和文件头前8个字节决定
        /// </summary>
        /// <param name="file"></param>
        /// <returns></returns>
        public static ImageType GetImageType(string file) {
            if (!System.IO.File.Exists(file))
                return ImageType.UNKNOWN;

            //先验证文件的后缀，如果文件后缀为图片格式那么再通过对文件头前几个字节进行验证
            //最后确定图片的格式
            string fileExtension = Path.GetExtension(file).ToUpper();
            if (IMAGE_EXTENSIONS.Contains(fileExtension)) {
                using (System.IO.Stream read = new FileStream(file, FileMode.Open, FileAccess.Read)) {
                    return GetImageType((Stream)read);
                }
            }

            return ImageType.UNKNOWN;
        }
        #endregion
        #region 视频
        public static VideoType GetVideoType(Stream stream) {
            byte[] header = new byte[16];
            stream.Seek(0, SeekOrigin.Begin);
            if (stream.Read(header, 0, header.Length) != header.Length)
                return VideoType.UNKNOWN;

            //QuickTime,从第4字节开始判断6D , 6F,6F,76 ,对应ascii：....moov
            if (header[4] == 0x6d && header[5] == 0x6f && header[6] == 0x6f && header[7] == 0x76)
                return VideoType.QUICKTIME;
            //RM,需要判断扩张情况,RM V10 和扩展对应的文件头MagicNumber的ASCII：.RMF
            //string strflags = System.Text.Encoding.ASCII.GetString(header,0,4/9);
            if (header[0] == 0x2e && header[1] == 0x52 && header[2] == 0x4d && header[3] == 0x46)
                return VideoType.RMVB;
            else if (header[0] == 0x2e && header[1] == 0x52 && header[2] == 0x4d && header[3] == 0x46 &&
                    header[4] == 0x00 && header[5] == 0x00 && header[6] == 0x00 && header[7] == 0x12 && header[8] == 0x00)
                return VideoType.RMVB;

            //SWF ,magic number="46.57.53"(FWS) , 压缩后43 57 53 （CWS）
            if (header[0] == 0x46 || header[0] == 0x43) {
                if (header[1] == 0x57 && header[2] == 0x53)
                    return VideoType.FLASH;
            }

            //FLV 
            if (header[0] == 0x46 && header[1] == 0x4C && header[2] == 0x56) {
                return VideoType.FLASH;
            }

            //WMV
            if (header[0] == 0x30 && header[1] == 0x26 && header[2] == 0xb2 && header[3] == 0x75 &&
              header[4] == 0x8e && header[5] == 0x66 && header[6] == 0xcf && header[7] == 0x11 &&
              header[8] == 0xa6 && header[9] == 0xd9 && header[10] == 0x00 && header[11] == 0xAA &&
              header[12] == 0x00 && header[13] == 0x62 && header[14] == 0xce && header[15] == 0x6c)
                return VideoType.WMV;

            //AVI,判断前4个字节和后8个字节
            if (header[0] == 0x52 && header[1] == 0x49 && header[2] == 0x46 && header[3] == 0x46 &&
                header[8] == 0x41 && header[9] == 0x56 && header[10] == 0x49 && header[11] == 0x20 &&
                header[12] == 0x4C && header[13] == 0x49 && header[14] == 0x53 && header[15] == 0x54)
                return VideoType.AVI;

            return VideoType.UNKNOWN;

        }


        public static VideoType GetVideoType(string file) {
            if (!System.IO.File.Exists(file))
                return VideoType.UNKNOWN;
            string fileextension = Path.GetExtension(file).ToUpper();
            if (VIDEO_EXTENSION.Contains(fileextension)) {
                //mp4单独判断
                if (fileextension.Equals(".mp4", StringComparison.CurrentCultureIgnoreCase))
                    return VideoType.MP4;
                using (System.IO.Stream read = new FileStream(file, FileMode.Open, FileAccess.Read)) {
                    return GetVideoType((Stream)read);
                }
            }

            return VideoType.UNKNOWN;
        }
        #endregion
        #region 音频
        public static AudioType GetAudioType(Stream stream) {
            byte[] header = new byte[16];
            stream.Seek(0, SeekOrigin.Begin );
            if (stream.Read(header, 0, header.Length) != header.Length)
                return AudioType.UNKNOWN;

            //Standard MIDI , 对应的ASCII：MThd ，不对    RMID格式做判断
            if (header[0] == 0x4d && header[1] == 0x54 && header[2] == 0x68 && header[3] == 0x64)
                return AudioType.MID;
            //MP3
            if (header[0] == 0xFF && header[1] == 0xFB && header[2] == 0x30)
                return AudioType.MP3;
            else if (header[0] == 0xFF && header[1] == 0xF3 && header[2] == 0x40)
                return AudioType.MP3;
            else if (header[0] == 0x49 && header[1] == 0x44)
                return AudioType.MP3;

            //WAV
            string strFlags = System.Text.Encoding.ASCII.GetString(header, 0, header.Length);
            //判断前4位和后7位（固定格式），中间为随机生成
            bool flag1=strFlags.Substring(0,4).Equals("RIFF",StringComparison.CurrentCultureIgnoreCase);
            bool flag2=strFlags.Substring(strFlags.Length-8,7).Equals("WAVEfmt",StringComparison.CurrentCultureIgnoreCase);
            if(flag1&&flag2) //if (strFlags.Equals("RIFF....WAVEfmt", StringComparison.CurrentCultureIgnoreCase))
                return AudioType.WAV;
            //WMA
            if (header[0] == 0x30 && header[1] == 0x26 && header[2] == 0xb2 && header[3] == 0x75 &&
               header[4] == 0x8e && header[5] == 0x66 && header[6] == 0xcf && header[7] == 0x11 &&
               header[8] == 0xa6 && header[9] == 0xd9 && header[10] == 0x00 && header[11] == 0xAA &&
               header[12] == 0x00 && header[13] == 0x62 && header[14] == 0xce && header[15] == 0x6c)
                return AudioType.WMA;

            return AudioType.UNKNOWN;
        }

        public static AudioType GetAudioType(string file) {
            if (!System.IO.File.Exists(file))
                return AudioType.UNKNOWN;
            string fileextension = Path.GetExtension(file).ToUpper();
            if (AUDIO_EXTENSION.Contains(fileextension)) {
                using (System.IO.Stream read = new FileStream(file, FileMode.Open, FileAccess.Read)) {
                    return GetAudioType((Stream)read);
                }
            }

            return AudioType.UNKNOWN;
        }
        #endregion

        /// <summary>
        /// 指定文件获取该文件的文件类型
        /// </summary>
        /// <param name="file"></param>
        /// <returns></returns>
        public static ResourceType GetResourceType(string file) {
            if (GetImageType(file) != ImageType.UNKNOWN)
                return ResourceType.Image;
            if (GetAudioType(file) != AudioType.UNKNOWN)
                return ResourceType.Audio;
            if (GetVideoType(file) != VideoType.UNKNOWN)
                return ResourceType.Video;

            return ResourceType.Unknown;
        }

        /// <summary>
        /// 过滤文件
        /// </summary>
        /// <param name="files"></param>
        /// <returns></returns>
        public static string[] FilterFile(string[] files) {
            List<string> lsFiles = new List<string>();
            foreach (var file in files) {
                if (GetResourceType(file) != ResourceType.Unknown)
                    lsFiles.Add(file);
            }

            return lsFiles.ToArray();
        }

        /// <summary>
        /// 验证当前文件是否为系统支持的文件格式
        /// </summary>
        /// <param name="file"></param>
        /// <returns></returns>
        public static bool IsSupportFileType(string file) {
            return GetResourceType(file) == ResourceType.Unknown ? false : true;
        }

        /// <summary>
        /// 判断文件是否为WMA文件
        /// </summary>
        /// <param name="file"></param>
        /// <returns></returns>
        public static bool IsWMA(string file) { return GetAudioType(file) == AudioType.WMA ? true : false; }

        /// <summary>
        /// 判断文件是否为GIF文件
        /// </summary>
        /// <param name="file"></param>
        /// <returns></returns>
        public static bool IsGif(string file) { return GetImageType(file) == ImageType.GIF ? true : false; }
}