30

我有一个网页,其中包含文件上传组件,仅将允许的文档类型上传到我的系统(仅限图像)。我不想使用正则表达式来确定文件类型和使用扩展名。

请让我知道是否有任何其他方法可以在 C# 中确定文件类型。

4

8 回答 8

38

我刚刚将我的VB.NET类转换为 C# 来检测 mime 类型。它们将通过嗅探文件的前 256 个字节(urlmon.dllInternet Explorer 使用的 fe)和一组已知类型的组合来识别。

您还可以使用它来检查文件是否是它所伪装的(如果扩展名与类型匹配)。

// check whether or not the uploaded file is an image:
var contentType = MimeTypes.GetContentType(FileUpload1.PostedFile.FileName);
if(contentType.StartsWith("image"))
{
    // do something with the image ...
}

这是课程:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.InteropServices;
using System.IO;

public class MimeTypes
{
    private static List<string> knownTypes;

    private static Dictionary<string, string> mimeTypes;

    [DllImport("urlmon.dll", CharSet = CharSet.Auto)]
    private static extern UInt32 FindMimeFromData(
        UInt32 pBC, [MarshalAs(UnmanagedType.LPStr)]
        string pwzUrl, [MarshalAs(UnmanagedType.LPArray)]
        byte[] pBuffer, UInt32 cbSize, [MarshalAs(UnmanagedType.LPStr)]
        string pwzMimeProposed, UInt32 dwMimeFlags, ref UInt32 ppwzMimeOut, UInt32 dwReserverd
    );

    public static string GetContentType(string fileName)
    {
        if (knownTypes == null || mimeTypes == null)
            InitializeMimeTypeLists();
        string contentType = "";
        string extension = System.IO.Path.GetExtension(fileName).Replace(".", "").ToLower();
        mimeTypes.TryGetValue(extension, out contentType);
        if (string.IsNullOrEmpty(contentType) || knownTypes.Contains(contentType))
        {
            string headerType = ScanFileForMimeType(fileName);
            if (headerType != "application/octet-stream" || string.IsNullOrEmpty(contentType))
                contentType = headerType;
        }
        return contentType;
    }

    private static string ScanFileForMimeType(string fileName)
    {
        try
        {
            byte[] buffer = new byte[256];
            using (FileStream fs = new FileStream(fileName, FileMode.Open))
            {
                int readLength = Convert.ToInt32(Math.Min(256, fs.Length));
                fs.Read(buffer, 0, readLength);
            }

            UInt32 mimeType = default(UInt32);
            FindMimeFromData(0, null, buffer, 256, null, 0, ref mimeType, 0);
            IntPtr mimeTypePtr = new IntPtr(mimeType);
            string mime = Marshal.PtrToStringUni(mimeTypePtr);
            Marshal.FreeCoTaskMem(mimeTypePtr);
            if (string.IsNullOrEmpty(mime))
                mime = "application/octet-stream";
            return mime;
        } catch (Exception ex)
        {
            return "application/octet-stream";
        }
    }

    private static void InitializeMimeTypeLists()
    {
        knownTypes = new string[] {
        "text/plain",
        "text/html",
        "text/xml",
        "text/richtext",
        "text/scriptlet",
        "audio/x-aiff",
        "audio/basic",
        "audio/mid",
        "audio/wav",
        "image/gif",
        "image/jpeg",
        "image/pjpeg",
        "image/png",
        "image/x-png",
        "image/tiff",
        "image/bmp",
        "image/x-xbitmap",
        "image/x-jg",
        "image/x-emf",
        "image/x-wmf",
        "video/avi",
        "video/mpeg",
        "application/octet-stream",
        "application/postscript",
        "application/base64",
        "application/macbinhex40",
        "application/pdf",
        "application/xml",
        "application/atom+xml",
        "application/rss+xml",
        "application/x-compressed",
        "application/x-zip-compressed",
        "application/x-gzip-compressed",
        "application/java",
        "application/x-msdownload"
    }.ToList();

        mimeTypes = new Dictionary<string, string>();
        mimeTypes.Add("3dm", "x-world/x-3dmf");
        mimeTypes.Add("3dmf", "x-world/x-3dmf");
        mimeTypes.Add("a", "application/octet-stream");
        mimeTypes.Add("aab", "application/x-authorware-bin");
        mimeTypes.Add("aam", "application/x-authorware-map");
        mimeTypes.Add("aas", "application/x-authorware-seg");
        mimeTypes.Add("abc", "text/vnd.abc");
        mimeTypes.Add("acgi", "text/html");
        mimeTypes.Add("afl", "video/animaflex");
        mimeTypes.Add("ai", "application/postscript");
        mimeTypes.Add("aif", "audio/aiff");
        mimeTypes.Add("aifc", "audio/aiff");
        mimeTypes.Add("aiff", "audio/aiff");
        mimeTypes.Add("aim", "application/x-aim");
        mimeTypes.Add("aip", "text/x-audiosoft-intra");
        mimeTypes.Add("ani", "application/x-navi-animation");
        mimeTypes.Add("aos", "application/x-nokia-9000-communicator-add-on-software");
        mimeTypes.Add("aps", "application/mime");
        mimeTypes.Add("arc", "application/octet-stream");
        mimeTypes.Add("arj", "application/arj");
        mimeTypes.Add("art", "image/x-jg");
        mimeTypes.Add("asf", "video/x-ms-asf");
        mimeTypes.Add("asm", "text/x-asm");
        mimeTypes.Add("asp", "text/asp");
        mimeTypes.Add("asx", "application/x-mplayer2");
        mimeTypes.Add("au", "audio/basic");
        mimeTypes.Add("avi", "video/avi");
        mimeTypes.Add("avs", "video/avs-video");
        mimeTypes.Add("bcpio", "application/x-bcpio");
        mimeTypes.Add("bin", "application/octet-stream");
        mimeTypes.Add("bm", "image/bmp");
        mimeTypes.Add("bmp", "image/bmp");
        mimeTypes.Add("boo", "application/book");
        mimeTypes.Add("book", "application/book");
        mimeTypes.Add("boz", "application/x-bzip2");
        mimeTypes.Add("bsh", "application/x-bsh");
        mimeTypes.Add("bz", "application/x-bzip");
        mimeTypes.Add("bz2", "application/x-bzip2");
        mimeTypes.Add("c", "text/plain");
        mimeTypes.Add("c++", "text/plain");
        mimeTypes.Add("cat", "application/vnd.ms-pki.seccat");
        mimeTypes.Add("cc", "text/plain");
        mimeTypes.Add("ccad", "application/clariscad");
        mimeTypes.Add("cco", "application/x-cocoa");
        mimeTypes.Add("cdf", "application/cdf");
        mimeTypes.Add("cer", "application/pkix-cert");
        mimeTypes.Add("cha", "application/x-chat");
        mimeTypes.Add("chat", "application/x-chat");
        mimeTypes.Add("class", "application/java");
        mimeTypes.Add("com", "application/octet-stream");
        mimeTypes.Add("conf", "text/plain");
        mimeTypes.Add("cpio", "application/x-cpio");
        mimeTypes.Add("cpp", "text/x-c");
        mimeTypes.Add("cpt", "application/x-cpt");
        mimeTypes.Add("crl", "application/pkcs-crl");
        mimeTypes.Add("css", "text/css");
        mimeTypes.Add("def", "text/plain");
        mimeTypes.Add("der", "application/x-x509-ca-cert");
        mimeTypes.Add("dif", "video/x-dv");
        mimeTypes.Add("dir", "application/x-director");
        mimeTypes.Add("dl", "video/dl");
        mimeTypes.Add("doc", "application/msword");
        mimeTypes.Add("dot", "application/msword");
        mimeTypes.Add("dp", "application/commonground");
        mimeTypes.Add("drw", "application/drafting");
        mimeTypes.Add("dump", "application/octet-stream");
        mimeTypes.Add("dv", "video/x-dv");
        mimeTypes.Add("dvi", "application/x-dvi");
        mimeTypes.Add("dwf", "drawing/x-dwf (old)");
        mimeTypes.Add("dwg", "application/acad");
        mimeTypes.Add("dxf", "application/dxf");
        mimeTypes.Add("eps", "application/postscript");
        mimeTypes.Add("es", "application/x-esrehber");
        mimeTypes.Add("etx", "text/x-setext");
        mimeTypes.Add("evy", "application/envoy");
        mimeTypes.Add("exe", "application/octet-stream");
        mimeTypes.Add("f", "text/plain");
        mimeTypes.Add("f90", "text/x-fortran");
        mimeTypes.Add("fdf", "application/vnd.fdf");
        mimeTypes.Add("fif", "image/fif");
        mimeTypes.Add("fli", "video/fli");
        mimeTypes.Add("flv", "video/x-flv");
        mimeTypes.Add("for", "text/x-fortran");
        mimeTypes.Add("fpx", "image/vnd.fpx");
        mimeTypes.Add("g", "text/plain");
        mimeTypes.Add("g3", "image/g3fax");
        mimeTypes.Add("gif", "image/gif");
        mimeTypes.Add("gl", "video/gl");
        mimeTypes.Add("gsd", "audio/x-gsm");
        mimeTypes.Add("gtar", "application/x-gtar");
        mimeTypes.Add("gz", "application/x-compressed");
        mimeTypes.Add("h", "text/plain");
        mimeTypes.Add("help", "application/x-helpfile");
        mimeTypes.Add("hgl", "application/vnd.hp-hpgl");
        mimeTypes.Add("hh", "text/plain");
        mimeTypes.Add("hlp", "application/x-winhelp");
        mimeTypes.Add("htc", "text/x-component");
        mimeTypes.Add("htm", "text/html");
        mimeTypes.Add("html", "text/html");
        mimeTypes.Add("htmls", "text/html");
        mimeTypes.Add("htt", "text/webviewhtml");
        mimeTypes.Add("htx", "text/html");
        mimeTypes.Add("ice", "x-conference/x-cooltalk");
        mimeTypes.Add("ico", "image/x-icon");
        mimeTypes.Add("idc", "text/plain");
        mimeTypes.Add("ief", "image/ief");
        mimeTypes.Add("iefs", "image/ief");
        mimeTypes.Add("iges", "application/iges");
        mimeTypes.Add("igs", "application/iges");
        mimeTypes.Add("ima", "application/x-ima");
        mimeTypes.Add("imap", "application/x-httpd-imap");
        mimeTypes.Add("inf", "application/inf");
        mimeTypes.Add("ins", "application/x-internett-signup");
        mimeTypes.Add("ip", "application/x-ip2");
        mimeTypes.Add("isu", "video/x-isvideo");
        mimeTypes.Add("it", "audio/it");
        mimeTypes.Add("iv", "application/x-inventor");
        mimeTypes.Add("ivr", "i-world/i-vrml");
        mimeTypes.Add("ivy", "application/x-livescreen");
        mimeTypes.Add("jam", "audio/x-jam");
        mimeTypes.Add("jav", "text/plain");
        mimeTypes.Add("java", "text/plain");
        mimeTypes.Add("jcm", "application/x-java-commerce");
        mimeTypes.Add("jfif", "image/jpeg");
        mimeTypes.Add("jfif-tbnl", "image/jpeg");
        mimeTypes.Add("jpe", "image/jpeg");
        mimeTypes.Add("jpeg", "image/jpeg");
        mimeTypes.Add("jpg", "image/jpeg");
        mimeTypes.Add("jps", "image/x-jps");
        mimeTypes.Add("js", "application/x-javascript");
        mimeTypes.Add("jut", "image/jutvision");
        mimeTypes.Add("kar", "audio/midi");
        mimeTypes.Add("ksh", "application/x-ksh");
        mimeTypes.Add("la", "audio/nspaudio");
        mimeTypes.Add("lam", "audio/x-liveaudio");
        mimeTypes.Add("latex", "application/x-latex");
        mimeTypes.Add("lha", "application/lha");
        mimeTypes.Add("lhx", "application/octet-stream");
        mimeTypes.Add("list", "text/plain");
        mimeTypes.Add("lma", "audio/nspaudio");
        mimeTypes.Add("log", "text/plain");
        mimeTypes.Add("lsp", "application/x-lisp");
        mimeTypes.Add("lst", "text/plain");
        mimeTypes.Add("lsx", "text/x-la-asf");
        mimeTypes.Add("ltx", "application/x-latex");
        mimeTypes.Add("lzh", "application/octet-stream");
        mimeTypes.Add("lzx", "application/lzx");
        mimeTypes.Add("m", "text/plain");
        mimeTypes.Add("m1v", "video/mpeg");
        mimeTypes.Add("m2a", "audio/mpeg");
        mimeTypes.Add("m2v", "video/mpeg");
        mimeTypes.Add("m3u", "audio/x-mpequrl");
        mimeTypes.Add("man", "application/x-troff-man");
        mimeTypes.Add("map", "application/x-navimap");
        mimeTypes.Add("mar", "text/plain");
        mimeTypes.Add("mbd", "application/mbedlet");
        mimeTypes.Add("mc$", "application/x-magic-cap-package-1.0");
        mimeTypes.Add("mcd", "application/mcad");
        mimeTypes.Add("mcf", "image/vasa");
        mimeTypes.Add("mcp", "application/netmc");
        mimeTypes.Add("me", "application/x-troff-me");
        mimeTypes.Add("mht", "message/rfc822");
        mimeTypes.Add("mhtml", "message/rfc822");
        mimeTypes.Add("mid", "audio/midi");
        mimeTypes.Add("midi", "audio/midi");
        mimeTypes.Add("mif", "application/x-frame");
        mimeTypes.Add("mime", "message/rfc822");
        mimeTypes.Add("mjf", "audio/x-vnd.audioexplosion.mjuicemediafile");
        mimeTypes.Add("mjpg", "video/x-motion-jpeg");
        mimeTypes.Add("mm", "application/base64");
        mimeTypes.Add("mme", "application/base64");
        mimeTypes.Add("mod", "audio/mod");
        mimeTypes.Add("moov", "video/quicktime");
        mimeTypes.Add("mov", "video/quicktime");
        mimeTypes.Add("movie", "video/x-sgi-movie");
        mimeTypes.Add("mp2", "audio/mpeg");
        mimeTypes.Add("mp3", "audio/mpeg3");
        mimeTypes.Add("mpa", "audio/mpeg");
        mimeTypes.Add("mpc", "application/x-project");
        mimeTypes.Add("mpe", "video/mpeg");
        mimeTypes.Add("mpeg", "video/mpeg");
        mimeTypes.Add("mpg", "video/mpeg");
        mimeTypes.Add("mpga", "audio/mpeg");
        mimeTypes.Add("mpp", "application/vnd.ms-project");
        mimeTypes.Add("mpt", "application/x-project");
        mimeTypes.Add("mpv", "application/x-project");
        mimeTypes.Add("mpx", "application/x-project");
        mimeTypes.Add("mrc", "application/marc");
        mimeTypes.Add("ms", "application/x-troff-ms");
        mimeTypes.Add("mv", "video/x-sgi-movie");
        mimeTypes.Add("my", "audio/make");
        mimeTypes.Add("mzz", "application/x-vnd.audioexplosion.mzz");
        mimeTypes.Add("nap", "image/naplps");
        mimeTypes.Add("naplps", "image/naplps");
        mimeTypes.Add("nc", "application/x-netcdf");
        mimeTypes.Add("ncm", "application/vnd.nokia.configuration-message");
        mimeTypes.Add("nif", "image/x-niff");
        mimeTypes.Add("niff", "image/x-niff");
        mimeTypes.Add("nix", "application/x-mix-transfer");
        mimeTypes.Add("nsc", "application/x-conference");
        mimeTypes.Add("nvd", "application/x-navidoc");
        mimeTypes.Add("o", "application/octet-stream");
        mimeTypes.Add("oda", "application/oda");
        mimeTypes.Add("omc", "application/x-omc");
        mimeTypes.Add("omcd", "application/x-omcdatamaker");
        mimeTypes.Add("omcr", "application/x-omcregerator");
        mimeTypes.Add("p", "text/x-pascal");
        mimeTypes.Add("p10", "application/pkcs10");
        mimeTypes.Add("p12", "application/pkcs-12");
        mimeTypes.Add("p7a", "application/x-pkcs7-signature");
        mimeTypes.Add("p7c", "application/pkcs7-mime");
        mimeTypes.Add("pas", "text/pascal");
        mimeTypes.Add("pbm", "image/x-portable-bitmap");
        mimeTypes.Add("pcl", "application/vnd.hp-pcl");
        mimeTypes.Add("pct", "image/x-pict");
        mimeTypes.Add("pcx", "image/x-pcx");
        mimeTypes.Add("pdf", "application/pdf");
        mimeTypes.Add("pfunk", "audio/make");
        mimeTypes.Add("pgm", "image/x-portable-graymap");
        mimeTypes.Add("pic", "image/pict");
        mimeTypes.Add("pict", "image/pict");
        mimeTypes.Add("pkg", "application/x-newton-compatible-pkg");
        mimeTypes.Add("pko", "application/vnd.ms-pki.pko");
        mimeTypes.Add("pl", "text/plain");
        mimeTypes.Add("plx", "application/x-pixclscript");
        mimeTypes.Add("pm", "image/x-xpixmap");
        mimeTypes.Add("png", "image/png");
        mimeTypes.Add("pnm", "application/x-portable-anymap");
        mimeTypes.Add("pot", "application/mspowerpoint");
        mimeTypes.Add("pov", "model/x-pov");
        mimeTypes.Add("ppa", "application/vnd.ms-powerpoint");
        mimeTypes.Add("ppm", "image/x-portable-pixmap");
        mimeTypes.Add("pps", "application/mspowerpoint");
        mimeTypes.Add("ppt", "application/mspowerpoint");
        mimeTypes.Add("ppz", "application/mspowerpoint");
        mimeTypes.Add("pre", "application/x-freelance");
        mimeTypes.Add("prt", "application/pro_eng");
        mimeTypes.Add("ps", "application/postscript");
        mimeTypes.Add("psd", "application/octet-stream");
        mimeTypes.Add("pvu", "paleovu/x-pv");
        mimeTypes.Add("pwz", "application/vnd.ms-powerpoint");
        mimeTypes.Add("py", "text/x-script.phyton");
        mimeTypes.Add("pyc", "applicaiton/x-bytecode.python");
        mimeTypes.Add("qcp", "audio/vnd.qcelp");
        mimeTypes.Add("qd3", "x-world/x-3dmf");
        mimeTypes.Add("qd3d", "x-world/x-3dmf");
        mimeTypes.Add("qif", "image/x-quicktime");
        mimeTypes.Add("qt", "video/quicktime");
        mimeTypes.Add("qtc", "video/x-qtc");
        mimeTypes.Add("qti", "image/x-quicktime");
        mimeTypes.Add("qtif", "image/x-quicktime");
        mimeTypes.Add("ra", "audio/x-pn-realaudio");
        mimeTypes.Add("ram", "audio/x-pn-realaudio");
        mimeTypes.Add("ras", "application/x-cmu-raster");
        mimeTypes.Add("rast", "image/cmu-raster");
        mimeTypes.Add("rexx", "text/x-script.rexx");
        mimeTypes.Add("rf", "image/vnd.rn-realflash");
        mimeTypes.Add("rgb", "image/x-rgb");
        mimeTypes.Add("rm", "application/vnd.rn-realmedia");
        mimeTypes.Add("rmi", "audio/mid");
        mimeTypes.Add("rmm", "audio/x-pn-realaudio");
        mimeTypes.Add("rmp", "audio/x-pn-realaudio");
        mimeTypes.Add("rng", "application/ringing-tones");
        mimeTypes.Add("rnx", "application/vnd.rn-realplayer");
        mimeTypes.Add("roff", "application/x-troff");
        mimeTypes.Add("rp", "image/vnd.rn-realpix");
        mimeTypes.Add("rpm", "audio/x-pn-realaudio-plugin");
        mimeTypes.Add("rt", "text/richtext");
        mimeTypes.Add("rtf", "text/richtext");
        mimeTypes.Add("rtx", "application/rtf");
        mimeTypes.Add("rv", "video/vnd.rn-realvideo");
        mimeTypes.Add("s", "text/x-asm");
        mimeTypes.Add("s3m", "audio/s3m");
        mimeTypes.Add("saveme", "application/octet-stream");
        mimeTypes.Add("sbk", "application/x-tbook");
        mimeTypes.Add("scm", "application/x-lotusscreencam");
        mimeTypes.Add("sdml", "text/plain");
        mimeTypes.Add("sdp", "application/sdp");
        mimeTypes.Add("sdr", "application/sounder");
        mimeTypes.Add("sea", "application/sea");
        mimeTypes.Add("set", "application/set");
        mimeTypes.Add("sgm", "text/sgml");
        mimeTypes.Add("sgml", "text/sgml");
        mimeTypes.Add("sh", "application/x-bsh");
        mimeTypes.Add("shtml", "text/html");
        mimeTypes.Add("sid", "audio/x-psid");
        mimeTypes.Add("sit", "application/x-sit");
        mimeTypes.Add("skd", "application/x-koan");
        mimeTypes.Add("skm", "application/x-koan");
        mimeTypes.Add("skp", "application/x-koan");
        mimeTypes.Add("skt", "application/x-koan");
        mimeTypes.Add("sl", "application/x-seelogo");
        mimeTypes.Add("smi", "application/smil");
        mimeTypes.Add("smil", "application/smil");
        mimeTypes.Add("snd", "audio/basic");
        mimeTypes.Add("sol", "application/solids");
        mimeTypes.Add("spc", "application/x-pkcs7-certificates");
        mimeTypes.Add("spl", "application/futuresplash");
        mimeTypes.Add("spr", "application/x-sprite");
        mimeTypes.Add("sprite", "application/x-sprite");
        mimeTypes.Add("src", "application/x-wais-source");
        mimeTypes.Add("ssi", "text/x-server-parsed-html");
        mimeTypes.Add("ssm", "application/streamingmedia");
        mimeTypes.Add("sst", "application/vnd.ms-pki.certstore");
        mimeTypes.Add("step", "application/step");
        mimeTypes.Add("stl", "application/sla");
        mimeTypes.Add("stp", "application/step");
        mimeTypes.Add("sv4cpio", "application/x-sv4cpio");
        mimeTypes.Add("sv4crc", "application/x-sv4crc");
        mimeTypes.Add("svf", "image/vnd.dwg");
        mimeTypes.Add("svr", "application/x-world");
        mimeTypes.Add("swf", "application/x-shockwave-flash");
        mimeTypes.Add("t", "application/x-troff");
        mimeTypes.Add("talk", "text/x-speech");
        mimeTypes.Add("tar", "application/x-tar");
        mimeTypes.Add("tbk", "application/toolbook");
        mimeTypes.Add("tcl", "application/x-tcl");
        mimeTypes.Add("tcsh", "text/x-script.tcsh");
        mimeTypes.Add("tex", "application/x-tex");
        mimeTypes.Add("texi", "application/x-texinfo");
        mimeTypes.Add("texinfo", "application/x-texinfo");
        mimeTypes.Add("text", "text/plain");
        mimeTypes.Add("tgz", "application/x-compressed");
        mimeTypes.Add("tif", "image/tiff");
        mimeTypes.Add("tr", "application/x-troff");
        mimeTypes.Add("tsi", "audio/tsp-audio");
        mimeTypes.Add("tsp", "audio/tsplayer");
        mimeTypes.Add("tsv", "text/tab-separated-values");
        mimeTypes.Add("turbot", "image/florian");
        mimeTypes.Add("txt", "text/plain");
        mimeTypes.Add("uil", "text/x-uil");
        mimeTypes.Add("uni", "text/uri-list");
        mimeTypes.Add("unis", "text/uri-list");
        mimeTypes.Add("unv", "application/i-deas");
        mimeTypes.Add("uri", "text/uri-list");
        mimeTypes.Add("uris", "text/uri-list");
        mimeTypes.Add("ustar", "application/x-ustar");
        mimeTypes.Add("uu", "application/octet-stream");
        mimeTypes.Add("vcd", "application/x-cdlink");
        mimeTypes.Add("vcs", "text/x-vcalendar");
        mimeTypes.Add("vda", "application/vda");
        mimeTypes.Add("vdo", "video/vdo");
        mimeTypes.Add("vew", "application/groupwise");
        mimeTypes.Add("viv", "video/vivo");
        mimeTypes.Add("vivo", "video/vivo");
        mimeTypes.Add("vmd", "application/vocaltec-media-desc");
        mimeTypes.Add("vmf", "application/vocaltec-media-file");
        mimeTypes.Add("voc", "audio/voc");
        mimeTypes.Add("vos", "video/vosaic");
        mimeTypes.Add("vox", "audio/voxware");
        mimeTypes.Add("vqe", "audio/x-twinvq-plugin");
        mimeTypes.Add("vqf", "audio/x-twinvq");
        mimeTypes.Add("vql", "audio/x-twinvq-plugin");
        mimeTypes.Add("vrml", "application/x-vrml");
        mimeTypes.Add("vrt", "x-world/x-vrt");
        mimeTypes.Add("vsd", "application/x-visio");
        mimeTypes.Add("vst", "application/x-visio");
        mimeTypes.Add("vsw", "application/x-visio");
        mimeTypes.Add("w60", "application/wordperfect6.0");
        mimeTypes.Add("w61", "application/wordperfect6.1");
        mimeTypes.Add("w6w", "application/msword");
        mimeTypes.Add("wav", "audio/wav");
        mimeTypes.Add("wb1", "application/x-qpro");
        mimeTypes.Add("wbmp", "image/vnd.wap.wbmp");
        mimeTypes.Add("web", "application/vnd.xara");
        mimeTypes.Add("wiz", "application/msword");
        mimeTypes.Add("wk1", "application/x-123");
        mimeTypes.Add("wmf", "windows/metafile");
        mimeTypes.Add("wml", "text/vnd.wap.wml");
        mimeTypes.Add("wmlc", "application/vnd.wap.wmlc");
        mimeTypes.Add("wmls", "text/vnd.wap.wmlscript");
        mimeTypes.Add("wmlsc", "application/vnd.wap.wmlscriptc");
        mimeTypes.Add("word", "application/msword");
        mimeTypes.Add("wp", "application/wordperfect");
        mimeTypes.Add("wp5", "application/wordperfect");
        mimeTypes.Add("wp6", "application/wordperfect");
        mimeTypes.Add("wpd", "application/wordperfect");
        mimeTypes.Add("wq1", "application/x-lotus");
        mimeTypes.Add("wri", "application/mswrite");
        mimeTypes.Add("wrl", "application/x-world");
        mimeTypes.Add("wrz", "model/vrml");
        mimeTypes.Add("wsc", "text/scriplet");
        mimeTypes.Add("wsrc", "application/x-wais-source");
        mimeTypes.Add("wtk", "application/x-wintalk");
        mimeTypes.Add("xbm", "image/x-xbitmap");
        mimeTypes.Add("xdr", "video/x-amt-demorun");
        mimeTypes.Add("xgz", "xgl/drawing");
        mimeTypes.Add("xif", "image/vnd.xiff");
        mimeTypes.Add("xl", "application/excel");
        mimeTypes.Add("xla", "application/excel");
        mimeTypes.Add("xlb", "application/excel");
        mimeTypes.Add("xlc", "application/excel");
        mimeTypes.Add("xld", "application/excel");
        mimeTypes.Add("xlk", "application/excel");
        mimeTypes.Add("xll", "application/excel");
        mimeTypes.Add("xlm", "application/excel");
        mimeTypes.Add("xls", "application/excel");
        mimeTypes.Add("xlsx", "application/excel");
        mimeTypes.Add("xlt", "application/excel");
        mimeTypes.Add("xlv", "application/excel");
        mimeTypes.Add("xlw", "application/excel");
        mimeTypes.Add("xm", "audio/xm");
        mimeTypes.Add("xml", "text/xml");
        mimeTypes.Add("xmz", "xgl/movie");
        mimeTypes.Add("xpix", "application/x-vnd.ls-xpix");
        mimeTypes.Add("xpm", "image/x-xpixmap");
        mimeTypes.Add("x-png", "image/png");
        mimeTypes.Add("xsr", "video/x-amt-showrun");
        mimeTypes.Add("xwd", "image/x-xwd");
        mimeTypes.Add("xyz", "chemical/x-pdb");
        mimeTypes.Add("z", "application/x-compress");
        mimeTypes.Add("zip", "application/x-compressed");
        mimeTypes.Add("zoo", "application/octet-stream");
        mimeTypes.Add("zsh", "text/x-script.zsh");
    }
}

当 MIME 类型未知且仅知道它是 不足够时,您必须更新此列表application/octet-stream。检查扩展名是否为 txt 但 mime 类型为二进制数据可能就足够了,因为这意味着该文件不是它所伪装的。


除此之外,使用RegularExpressionValidator.

例如(仅 jpg 图像):

<asp:FileUpload ID="FileUpload1" runat="server" /><br />
<br />
<asp:Button ID="Button1" runat="server" OnClick="Button1_Click" 
 Text="Upload File" />&nbsp;<br />
<br />
<asp:Label ID="Label1" runat="server"></asp:Label>
<asp:RegularExpressionValidator 
 id="RegularExpressionValidator1" runat="server" 
 ErrorMessage="Only jpeg files are allowed!" 
 ValidationExpression="^(([a-zA-Z]:)|(\\{2}\w+)\$?)(\\(\w[\w].*))
    +(.jpg|.JPG|.jpeg|.JPEG)$" 
 ControlToValidate="FileUpload1"></asp:RegularExpressionValidator>

在代码隐藏中:

if (FileUpload1.HasFile)
{
    string fileExt = 
       System.IO.Path.GetExtension(FileUpload1.FileName);

    if (fileExt == ".jpeg" || fileExt == ".jpg")
    {
        //do what you want with this image
    }
    else
    {
        Label1.Text = "Only .jpeg files are allowed!";
    }
}
于 2012-07-18T18:35:38.393 回答
6

.NET 中有一个帮助程序类,称为 Path。你需要的是

Path.GetExtension();

它位于 System.IO 命名空间中。

于 2012-07-18T18:13:23.570 回答
5

像这样编写代码从来都不是一个好主意:

string fileExt = System.IO.Path.GetExtension(FileUpload1.FileName);

if (fileExt == ".jpeg" || fileExt == ".jpg")
{
    //do what you want with this image
}

原因是它会给你文件名的扩展名。让我们假设用户足够聪明,可以将文件名从 foo.exe 更改为 foo.png 并上传。在此代码示例验证将通过,这对您不利。

识别文件类型的唯一适当方法是检查它的魔术字节。根据维基百科,这个术语(“幻数”)用于文件开头的一组特定的 2 字节标识符,但由于任何二进制序列都可以被视为一个数字,因此文件格式的任何特征都可以唯一区分它可用于识别。这种方法可以更好地保证正确识别格式,并且通常可以确定有关文件的更精确信息。参考原帖

正因为如此,一年前我遇到了同样的问题,我创建了一个可以帮助你解决这种情况的库。它易于使用,只需几行代码,您就会很安全。

于 2020-03-14T21:04:22.463 回答
4

你可以使用 Myrmec 来识别文件类型,这个库使用文件字节头。这个库在 nuget "Myrmec" 上可用,这是repo,myrmec 也支持 mime 类型,你可以试试。代码将是这样的:

// create a sniffer instance.
Sniffer sniffer = new Sniffer();

// populate with mata data.
sniffer.Populate(FileTypes.CommonFileTypes);

// get file head byte, may be 20 bytes enough.
byte[] fileHead = ReadFileHead();

// start match.
List<string> results = sniffer.Match(fileHead);
于 2018-02-10T04:48:57.467 回答
3

看到一个与此类似的示例。应该为您指明正确的方向。来自 msdn 网站。

string fileName = @"C:\mydir.old\myfile.ext";
string path = @"C:\mydir.old\";
string extension;

extension = Path.GetExtension(fileName);
Console.WriteLine("GetExtension('{0}') returns '{1}'", 
fileName, extension);

extension = Path.GetExtension(path);
Console.WriteLine("GetExtension('{0}') returns '{1}'", 
path, extension);

// This code produces output similar to the following:
//
// GetExtension('C:\mydir.old\myfile.ext') returns '.ext'
// GetExtension('C:\mydir.old\') returns ''
于 2012-07-18T18:15:46.630 回答
2

听起来您正在寻找FindMimeFromData. 这个问题中有很多额外的信息和代码。

于 2012-07-18T18:16:17.773 回答
1
        HttpFileCollection hfc = Request.Files;
        for (int i = 0; i < hfc.Count - 1; i++)
        {
            HttpPostedFile hpf = hfc(i);
            if (hpf.ContentType == "image/jpeg")
            {

                //its a jpeg

            }
        }
于 2012-07-18T18:15:00.333 回答
0
  • 使用 FileExtensionContentTypeProvider()
[HttpGet]
public string Get(string fileName)
{
    var provider = new FileExtensionContentTypeProvider();
    string contentType;
    if(!provider.TryGetContentType(fileName, out contentType))
    {
        contentType = "application/octet-stream";
    }
    return contentType;
}
于 2020-07-24T16:30:18.400 回答