使用.NET，如何根据文件签名而不是扩展名find文件的MIMEtypes
我正在寻找一个简单的方法来获得一个MIMEtypes的文件扩展名是不正确的或不给，类似于这个问题只有在。
Urlmon.dll中有一个名为FindMimeFromData的函数。
从文档
MIMEtypes检测或“数据嗅探”是指从二进制数据中确定适当的MIMEtypes的过程。 最终结果取决于服务器提供的MIMEtypes标头，文件扩展名和/或数据本身的组合。 通常，只有前256个字节的数据是重要的。
因此，从文件中读取第一个（最多）256个字节并将其传递给FindMimeFromData 。
我最终使用了urlmon.dll。 我认为会有一个更简单的方法，但这个工作。 我包括代码来帮助其他人，并让我再次find它，如果我需要它。
using System.Runtime.InteropServices;
…
[DllImport(@"urlmon.dll", CharSet = CharSet.Auto)] private extern static System.UInt32 FindMimeFromData( System.UInt32 pBC, [MarshalAs(UnmanagedType.LPStr)] System.String pwzUrl, [MarshalAs(UnmanagedType.LPArray)] byte[] pBuffer, System.UInt32 cbSize, [MarshalAs(UnmanagedType.LPStr)] System.String pwzMimeProposed, System.UInt32 dwMimeFlags, out System.UInt32 ppwzMimeOut, System.UInt32 dwReserverd ); public static string getMimeFromFile(string filename) { if (!File.Exists(filename)) throw new FileNotFoundException(filename + " not found"); byte[] buffer = new byte[256]; using (FileStream fs = new FileStream(filename, FileMode.Open)) { if (fs.Length >= 256) fs.Read(buffer, 0, 256); else fs.Read(buffer, 0, (int)fs.Length); } try { System.UInt32 mimetype; FindMimeFromData(0, null, buffer, 256, null, 0, out mimetype, 0); System.IntPtr mimeTypePtr = new IntPtr(mimetype); string mime = Marshal.PtrToStringUni(mimeTypePtr); Marshal.FreeCoTaskMem(mimeTypePtr); return mime; } catch (Exception e) { return "unknown/unknown"; } }
我发现了一个硬编码的解决scheme，我希望我会帮助别人：
public static class MIMEAssistant { private static readonly Dictionary<string, string> MIMETypesDictionary = new Dictionary<string, string> { {"ai", "application/postscript"}, {"aif", "audio/x-aiff"}, {"aifc", "audio/x-aiff"}, {"aiff", "audio/x-aiff"}, {"asc", "text/plain"}, {"atom", "application/atom+xml"}, {"au", "audio/basic"}, {"avi", "video/x-msvideo"}, {"bcpio", "application/x-bcpio"}, {"bin", "application/octet-stream"}, {"bmp", "image/bmp"}, {"cdf", "application/x-netcdf"}, {"cgm", "image/cgm"}, {"class", "application/octet-stream"}, {"cpio", "application/x-cpio"}, {"cpt", "application/mac-compactpro"}, {"csh", "application/x-csh"}, {"css", "text/css"}, {"dcr", "application/x-director"}, {"dif", "video/x-dv"}, {"dir", "application/x-director"}, {"djv", "image/vnd.djvu"}, {"djvu", "image/vnd.djvu"}, {"dll", "application/octet-stream"}, {"dmg", "application/octet-stream"}, {"dms", "application/octet-stream"}, {"doc", "application/msword"}, {"docx","application/vnd.openxmlformats-officedocument.wordprocessingml.document"}, {"dotx", "application/vnd.openxmlformats-officedocument.wordprocessingml.template"}, {"docm","application/vnd.ms-word.document.macroEnabled.12"}, {"dotm","application/vnd.ms-word.template.macroEnabled.12"}, {"dtd", "application/xml-dtd"}, {"dv", "video/x-dv"}, {"dvi", "application/x-dvi"}, {"dxr", "application/x-director"}, {"eps", "application/postscript"}, {"etx", "text/x-setext"}, {"exe", "application/octet-stream"}, {"ez", "application/andrew-inset"}, {"gif", "image/gif"}, {"gram", "application/srgs"}, {"grxml", "application/srgs+xml"}, {"gtar", "application/x-gtar"}, {"hdf", "application/x-hdf"}, {"hqx", "application/mac-binhex40"}, {"htm", "text/html"}, {"html", "text/html"}, {"ice", "x-conference/x-cooltalk"}, {"ico", "image/x-icon"}, {"ics", "text/calendar"}, {"ief", "image/ief"}, {"ifb", "text/calendar"}, {"iges", "model/iges"}, {"igs", "model/iges"}, {"jnlp", "application/x-java-jnlp-file"}, {"jp2", "image/jp2"}, {"jpe", "image/jpeg"}, {"jpeg", "image/jpeg"}, {"jpg", "image/jpeg"}, {"js", "application/x-javascript"}, {"kar", "audio/midi"}, {"latex", "application/x-latex"}, {"lha", "application/octet-stream"}, {"lzh", "application/octet-stream"}, {"m3u", "audio/x-mpegurl"}, {"m4a", "audio/mp4a-latm"}, {"m4b", "audio/mp4a-latm"}, {"m4p", "audio/mp4a-latm"}, {"m4u", "video/vnd.mpegurl"}, {"m4v", "video/x-m4v"}, {"mac", "image/x-macpaint"}, {"man", "application/x-troff-man"}, {"mathml", "application/mathml+xml"}, {"me", "application/x-troff-me"}, {"mesh", "model/mesh"}, {"mid", "audio/midi"}, {"midi", "audio/midi"}, {"mif", "application/vnd.mif"}, {"mov", "video/quicktime"}, {"movie", "video/x-sgi-movie"}, {"mp2", "audio/mpeg"}, {"mp3", "audio/mpeg"}, {"mp4", "video/mp4"}, {"mpe", "video/mpeg"}, {"mpeg", "video/mpeg"}, {"mpg", "video/mpeg"}, {"mpga", "audio/mpeg"}, {"ms", "application/x-troff-ms"}, {"msh", "model/mesh"}, {"mxu", "video/vnd.mpegurl"}, {"nc", "application/x-netcdf"}, {"oda", "application/oda"}, {"ogg", "application/ogg"}, {"pbm", "image/x-portable-bitmap"}, {"pct", "image/pict"}, {"pdb", "chemical/x-pdb"}, {"pdf", "application/pdf"}, {"pgm", "image/x-portable-graymap"}, {"pgn", "application/x-chess-pgn"}, {"pic", "image/pict"}, {"pict", "image/pict"}, {"png", "image/png"}, {"pnm", "image/x-portable-anymap"}, {"pnt", "image/x-macpaint"}, {"pntg", "image/x-macpaint"}, {"ppm", "image/x-portable-pixmap"}, {"ppt", "application/vnd.ms-powerpoint"}, {"pptx","application/vnd.openxmlformats-officedocument.presentationml.presentation"}, {"potx","application/vnd.openxmlformats-officedocument.presentationml.template"}, {"ppsx","application/vnd.openxmlformats-officedocument.presentationml.slideshow"}, {"ppam","application/vnd.ms-powerpoint.addin.macroEnabled.12"}, {"pptm","application/vnd.ms-powerpoint.presentation.macroEnabled.12"}, {"potm","application/vnd.ms-powerpoint.template.macroEnabled.12"}, {"ppsm","application/vnd.ms-powerpoint.slideshow.macroEnabled.12"}, {"ps", "application/postscript"}, {"qt", "video/quicktime"}, {"qti", "image/x-quicktime"}, {"qtif", "image/x-quicktime"}, {"ra", "audio/x-pn-realaudio"}, {"ram", "audio/x-pn-realaudio"}, {"ras", "image/x-cmu-raster"}, {"rdf", "application/rdf+xml"}, {"rgb", "image/x-rgb"}, {"rm", "application/vnd.rn-realmedia"}, {"roff", "application/x-troff"}, {"rtf", "text/rtf"}, {"rtx", "text/richtext"}, {"sgm", "text/sgml"}, {"sgml", "text/sgml"}, {"sh", "application/x-sh"}, {"shar", "application/x-shar"}, {"silo", "model/mesh"}, {"sit", "application/x-stuffit"}, {"skd", "application/x-koan"}, {"skm", "application/x-koan"}, {"skp", "application/x-koan"}, {"skt", "application/x-koan"}, {"smi", "application/smil"}, {"smil", "application/smil"}, {"snd", "audio/basic"}, {"so", "application/octet-stream"}, {"spl", "application/x-futuresplash"}, {"src", "application/x-wais-source"}, {"sv4cpio", "application/x-sv4cpio"}, {"sv4crc", "application/x-sv4crc"}, {"svg", "image/svg+xml"}, {"swf", "application/x-shockwave-flash"}, {"t", "application/x-troff"}, {"tar", "application/x-tar"}, {"tcl", "application/x-tcl"}, {"tex", "application/x-tex"}, {"texi", "application/x-texinfo"}, {"texinfo", "application/x-texinfo"}, {"tif", "image/tiff"}, {"tiff", "image/tiff"}, {"tr", "application/x-troff"}, {"tsv", "text/tab-separated-values"}, {"txt", "text/plain"}, {"ustar", "application/x-ustar"}, {"vcd", "application/x-cdlink"}, {"vrml", "model/vrml"}, {"vxml", "application/voicexml+xml"}, {"wav", "audio/x-wav"}, {"wbmp", "image/vnd.wap.wbmp"}, {"wbmxl", "application/vnd.wap.wbxml"}, {"wml", "text/vnd.wap.wml"}, {"wmlc", "application/vnd.wap.wmlc"}, {"wmls", "text/vnd.wap.wmlscript"}, {"wmlsc", "application/vnd.wap.wmlscriptc"}, {"wrl", "model/vrml"}, {"xbm", "image/x-xbitmap"}, {"xht", "application/xhtml+xml"}, {"xhtml", "application/xhtml+xml"}, {"xls", "application/vnd.ms-excel"}, {"xml", "application/xml"}, {"xpm", "image/x-xpixmap"}, {"xsl", "application/xml"}, {"xlsx","application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"}, {"xltx","application/vnd.openxmlformats-officedocument.spreadsheetml.template"}, {"xlsm","application/vnd.ms-excel.sheet.macroEnabled.12"}, {"xltm","application/vnd.ms-excel.template.macroEnabled.12"}, {"xlam","application/vnd.ms-excel.addin.macroEnabled.12"}, {"xlsb","application/vnd.ms-excel.sheet.binary.macroEnabled.12"}, {"xslt", "application/xslt+xml"}, {"xul", "application/vnd.mozilla.xul+xml"}, {"xwd", "image/x-xwindowdump"}, {"xyz", "chemical/x-xyz"}, {"zip", "application/zip"} }; public static string GetMIMEType(string fileName) { //get file extension string extension = Path.GetExtension(fileName).ToLowerInvariant(); if (extension.Length > 0 && MIMETypesDictionary.ContainsKey(extension.Remove(0, 1))) { return MIMETypesDictionary[extension.Remove(0, 1)]; } return "unknown/unknown"; } }
编辑：只使用Mime侦探
我使用字节数组序列来确定给定文件的正确的MIMEtypes。 这只是看看文件名的文件扩展名的优点是，如果用户要重命名文件以绕过某些文件types上传限制，文件扩展名将无法捕捉到这一点。 另一方面，通过字节数组获取文件签名将停止发生恶作剧行为。
这里是C＃中的一个例子：
public class MimeType { private static readonly byte[] BMP = { 66, 77 }; private static readonly byte[] DOC = { 208, 207, 17, 224, 161, 177, 26, 225 }; private static readonly byte[] EXE_DLL = { 77, 90 }; private static readonly byte[] GIF = { 71, 73, 70, 56 }; private static readonly byte[] ICO = { 0, 0, 1, 0 }; private static readonly byte[] JPG = { 255, 216, 255 }; private static readonly byte[] MP3 = { 255, 251, 48 }; private static readonly byte[] OGG = { 79, 103, 103, 83, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0 }; private static readonly byte[] PDF = { 37, 80, 68, 70, 45, 49, 46 }; private static readonly byte[] PNG = { 137, 80, 78, 71, 13, 10, 26, 10, 0, 0, 0, 13, 73, 72, 68, 82 }; private static readonly byte[] RAR = { 82, 97, 114, 33, 26, 7, 0 }; private static readonly byte[] SWF = { 70, 87, 83 }; private static readonly byte[] TIFF = { 73, 73, 42, 0 }; private static readonly byte[] TORRENT = { 100, 56, 58, 97, 110, 110, 111, 117, 110, 99, 101 }; private static readonly byte[] TTF = { 0, 1, 0, 0, 0 }; private static readonly byte[] WAV_AVI = { 82, 73, 70, 70 }; private static readonly byte[] WMV_WMA = { 48, 38, 178, 117, 142, 102, 207, 17, 166, 217, 0, 170, 0, 98, 206, 108 }; private static readonly byte[] ZIP_DOCX = { 80, 75, 3, 4 }; public static string GetMimeType(byte[] file, string fileName) { string mime = "application/octet-stream"; //DEFAULT UNKNOWN MIME TYPE //Ensure that the filename isn't empty or null if (string.IsNullOrWhiteSpace(fileName)) { return mime; } //Get the file extension string extension = Path.GetExtension(fileName) == null ? string.Empty : Path.GetExtension(fileName).ToUpper(); //Get the MIME Type if (file.Take(2).SequenceEqual(BMP)) { mime = "image/bmp"; } else if (file.Take(8).SequenceEqual(DOC)) { mime = "application/msword"; } else if (file.Take(2).SequenceEqual(EXE_DLL)) { mime = "application/x-msdownload"; //both use same mime type } else if (file.Take(4).SequenceEqual(GIF)) { mime = "image/gif"; } else if (file.Take(4).SequenceEqual(ICO)) { mime = "image/x-icon"; } else if (file.Take(3).SequenceEqual(JPG)) { mime = "image/jpeg"; } else if (file.Take(3).SequenceEqual(MP3)) { mime = "audio/mpeg"; } else if (file.Take(14).SequenceEqual(OGG)) { if (extension == ".OGX") { mime = "application/ogg"; } else if (extension == ".OGA") { mime = "audio/ogg"; } else { mime = "video/ogg"; } } else if (file.Take(7).SequenceEqual(PDF)) { mime = "application/pdf"; } else if (file.Take(16).SequenceEqual(PNG)) { mime = "image/png"; } else if (file.Take(7).SequenceEqual(RAR)) { mime = "application/x-rar-compressed"; } else if (file.Take(3).SequenceEqual(SWF)) { mime = "application/x-shockwave-flash"; } else if (file.Take(4).SequenceEqual(TIFF)) { mime = "image/tiff"; } else if (file.Take(11).SequenceEqual(TORRENT)) { mime = "application/x-bittorrent"; } else if (file.Take(5).SequenceEqual(TTF)) { mime = "application/x-font-ttf"; } else if (file.Take(4).SequenceEqual(WAV_AVI)) { mime = extension == ".AVI" ? "video/x-msvideo" : "audio/x-wav"; } else if (file.Take(16).SequenceEqual(WMV_WMA)) { mime = extension == ".WMA" ? "audio/x-ms-wma" : "video/x-ms-wmv"; } else if (file.Take(4).SequenceEqual(ZIP_DOCX)) { mime = extension == ".DOCX" ? "application/vnd.openxmlformats-officedocument.wordprocessingml.document" : "application/x-zip-compressed"; } return mime; } }
注意我处理DOCX文件types的方式不同，因为DOCX实际上只是一个ZIP文件。 在这种情况下，我只需检查文件扩展名，一旦我确认它具有该序列。 这个例子对于一些人来说是远远不够的，但是你可以很容易的添加你自己的。
如果你想添加更多的MIMEtypes，你可以从这里获得许多不同文件types的字节数组序列。 另外， 这里还有另一个关于文件签名的好资源 。
如果一切都失败了，我会做很多次遍历一个特定types的文件，然后在这个文件的字节序列中寻找一个模式。 最后，这还是基本的validation，不能用于确定文件types的100％certificate。
如果您使用的是.NET Framework 4.5或更高版本，现在有一个MimeMapping.GetMimeMapping（filename）方法，它将返回一个正确的Mime映射的string作为传入的文件名。 请注意，这使用文件扩展名，而不是文件本身的数据。
文档位于http://msdn.microsoft.com/zh-CN/library/system.web.mimemapping.getmimemapping
你也可以看看registry。
using System.IO; using Microsoft.Win32; string GetMimeType(FileInfo fileInfo) { string mimeType = "application/unknown"; RegistryKey regKey = Registry.ClassesRoot.OpenSubKey( fileInfo.Extension.ToLower() ); if(regKey != null) { object contentType = regKey.GetValue("Content Type"); if(contentType != null) mimeType = contentType.ToString(); } return mimeType; }
无论如何，你将不得不挖掘MIME数据库 – 无论它们是从扩展映射还是神奇数字都有点微不足道 – Windowsregistry就是这样一个地方。 对于一个平台独立的解决scheme，虽然人们不得不将这个数据库与代码（或作为独立的库）。
我使用混合解决scheme：
using System.Runtime.InteropServices; [DllImport (@"urlmon.dll", CharSet = CharSet.Auto)] private extern static System.UInt32 FindMimeFromData( System.UInt32 pBC, [MarshalAs(UnmanagedType.LPStr)] System.String pwzUrl, [MarshalAs(UnmanagedType.LPArray)] byte[] pBuffer, System.UInt32 cbSize, [MarshalAs(UnmanagedType.LPStr)] System.String pwzMimeProposed, System.UInt32 dwMimeFlags, out System.UInt32 ppwzMimeOut, System.UInt32 dwReserverd ); private string GetMimeFromRegistry (string Filename) { string mime = "application/octetstream"; string ext = System.IO.Path.GetExtension(Filename).ToLower(); Microsoft.Win32.RegistryKey rk = Microsoft.Win32.Registry.ClassesRoot.OpenSubKey(ext); if (rk != null && rk.GetValue("Content Type") != null) mime = rk.GetValue("Content Type").ToString(); return mime; } public string GetMimeTypeFromFileAndRegistry (string filename) { if (!File.Exists(filename)) { return GetMimeFromRegistry (filename); } byte[] buffer = new byte[256]; using (FileStream fs = new FileStream(filename, FileMode.Open)) { if (fs.Length >= 256) fs.Read(buffer, 0, 256); else fs.Read(buffer, 0, (int)fs.Length); } try { System.UInt32 mimetype; FindMimeFromData(0, null, buffer, 256, null, 0, out mimetype, 0); System.IntPtr mimeTypePtr = new IntPtr(mimetype); string mime = Marshal.PtrToStringUni(mimeTypePtr); Marshal.FreeCoTaskMem(mimeTypePtr); if (string.IsNullOrWhiteSpace (mime) || mime =="text/plain" || mime == "application/octet-stream") { return GetMimeFromRegistry (filename); } return mime; } catch (Exception e) { return GetMimeFromRegistry (filename); } }
我发现这个有用。 对于VB.NET开发人员：
Public Shared Function GetFromFileName(ByVal fileName As String) As String Return GetFromExtension(Path.GetExtension(fileName).Remove(0, 1)) End Function Public Shared Function GetFromExtension(ByVal extension As String) As String If extension.StartsWith("."c) Then extension = extension.Remove(0, 1) End If If MIMETypesDictionary.ContainsKey(extension) Then Return MIMETypesDictionary(extension) End If Return "unknown/unknown" End Function Private Shared ReadOnly MIMETypesDictionary As New Dictionary(Of String, String)() From { _ {"ai", "application/postscript"}, _ {"aif", "audio/x-aiff"}, _ {"aifc", "audio/x-aiff"}, _ {"aiff", "audio/x-aiff"}, _ {"asc", "text/plain"}, _ {"atom", "application/atom+xml"}, _ {"au", "audio/basic"}, _ {"avi", "video/x-msvideo"}, _ {"bcpio", "application/x-bcpio"}, _ {"bin", "application/octet-stream"}, _ {"bmp", "image/bmp"}, _ {"cdf", "application/x-netcdf"}, _ {"cgm", "image/cgm"}, _ {"class", "application/octet-stream"}, _ {"cpio", "application/x-cpio"}, _ {"cpt", "application/mac-compactpro"}, _ {"csh", "application/x-csh"}, _ {"css", "text/css"}, _ {"dcr", "application/x-director"}, _ {"dif", "video/x-dv"}, _ {"dir", "application/x-director"}, _ {"djv", "image/vnd.djvu"}, _ {"djvu", "image/vnd.djvu"}, _ {"dll", "application/octet-stream"}, _ {"dmg", "application/octet-stream"}, _ {"dms", "application/octet-stream"}, _ {"doc", "application/msword"}, _ {"dtd", "application/xml-dtd"}, _ {"dv", "video/x-dv"}, _ {"dvi", "application/x-dvi"}, _ {"dxr", "application/x-director"}, _ {"eps", "application/postscript"}, _ {"etx", "text/x-setext"}, _ {"exe", "application/octet-stream"}, _ {"ez", "application/andrew-inset"}, _ {"gif", "image/gif"}, _ {"gram", "application/srgs"}, _ {"grxml", "application/srgs+xml"}, _ {"gtar", "application/x-gtar"}, _ {"hdf", "application/x-hdf"}, _ {"hqx", "application/mac-binhex40"}, _ {"htm", "text/html"}, _ {"html", "text/html"}, _ {"ice", "x-conference/x-cooltalk"}, _ {"ico", "image/x-icon"}, _ {"ics", "text/calendar"}, _ {"ief", "image/ief"}, _ {"ifb", "text/calendar"}, _ {"iges", "model/iges"}, _ {"igs", "model/iges"}, _ {"jnlp", "application/x-java-jnlp-file"}, _ {"jp2", "image/jp2"}, _ {"jpe", "image/jpeg"}, _ {"jpeg", "image/jpeg"}, _ {"jpg", "image/jpeg"}, _ {"js", "application/x-javascript"}, _ {"kar", "audio/midi"}, _ {"latex", "application/x-latex"}, _ {"lha", "application/octet-stream"}, _ {"lzh", "application/octet-stream"}, _ {"m3u", "audio/x-mpegurl"}, _ {"m4a", "audio/mp4a-latm"}, _ {"m4b", "audio/mp4a-latm"}, _ {"m4p", "audio/mp4a-latm"}, _ {"m4u", "video/vnd.mpegurl"}, _ {"m4v", "video/x-m4v"}, _ {"mac", "image/x-macpaint"}, _ {"man", "application/x-troff-man"}, _ {"mathml", "application/mathml+xml"}, _ {"me", "application/x-troff-me"}, _ {"mesh", "model/mesh"}, _ {"mid", "audio/midi"}, _ {"midi", "audio/midi"}, _ {"mif", "application/vnd.mif"}, _ {"mov", "video/quicktime"}, _ {"movie", "video/x-sgi-movie"}, _ {"mp2", "audio/mpeg"}, _ {"mp3", "audio/mpeg"}, _ {"mp4", "video/mp4"}, _ {"mpe", "video/mpeg"}, _ {"mpeg", "video/mpeg"}, _ {"mpg", "video/mpeg"}, _ {"mpga", "audio/mpeg"}, _ {"ms", "application/x-troff-ms"}, _ {"msh", "model/mesh"}, _ {"mxu", "video/vnd.mpegurl"}, _ {"nc", "application/x-netcdf"}, _ {"oda", "application/oda"}, _ {"ogg", "application/ogg"}, _ {"pbm", "image/x-portable-bitmap"}, _ {"pct", "image/pict"}, _ {"pdb", "chemical/x-pdb"}, _ {"pdf", "application/pdf"}, _ {"pgm", "image/x-portable-graymap"}, _ {"pgn", "application/x-chess-pgn"}, _ {"pic", "image/pict"}, _ {"pict", "image/pict"}, _ {"png", "image/png"}, _ {"pnm", "image/x-portable-anymap"}, _ {"pnt", "image/x-macpaint"}, _ {"pntg", "image/x-macpaint"}, _ {"ppm", "image/x-portable-pixmap"}, _ {"ppt", "application/vnd.ms-powerpoint"}, _ {"ps", "application/postscript"}, _ {"qt", "video/quicktime"}, _ {"qti", "image/x-quicktime"}, _ {"qtif", "image/x-quicktime"}, _ {"ra", "audio/x-pn-realaudio"}, _ {"ram", "audio/x-pn-realaudio"}, _ {"ras", "image/x-cmu-raster"}, _ {"rdf", "application/rdf+xml"}, _ {"rgb", "image/x-rgb"}, _ {"rm", "application/vnd.rn-realmedia"}, _ {"roff", "application/x-troff"}, _ {"rtf", "text/rtf"}, _ {"rtx", "text/richtext"}, _ {"sgm", "text/sgml"}, _ {"sgml", "text/sgml"}, _ {"sh", "application/x-sh"}, _ {"shar", "application/x-shar"}, _ {"silo", "model/mesh"}, _ {"sit", "application/x-stuffit"}, _ {"skd", "application/x-koan"}, _ {"skm", "application/x-koan"}, _ {"skp", "application/x-koan"}, _ {"skt", "application/x-koan"}, _ {"smi", "application/smil"}, _ {"smil", "application/smil"}, _ {"snd", "audio/basic"}, _ {"so", "application/octet-stream"}, _ {"spl", "application/x-futuresplash"}, _ {"src", "application/x-wais-source"}, _ {"sv4cpio", "application/x-sv4cpio"}, _ {"sv4crc", "application/x-sv4crc"}, _ {"svg", "image/svg+xml"}, _ {"swf", "application/x-shockwave-flash"}, _ {"t", "application/x-troff"}, _ {"tar", "application/x-tar"}, _ {"tcl", "application/x-tcl"}, _ {"tex", "application/x-tex"}, _ {"texi", "application/x-texinfo"}, _ {"texinfo", "application/x-texinfo"}, _ {"tif", "image/tiff"}, _ {"tiff", "image/tiff"}, _ {"tr", "application/x-troff"}, _ {"tsv", "text/tab-separated-values"}, _ {"txt", "text/plain"}, _ {"ustar", "application/x-ustar"}, _ {"vcd", "application/x-cdlink"}, _ {"vrml", "model/vrml"}, _ {"vxml", "application/voicexml+xml"}, _ {"wav", "audio/x-wav"}, _ {"wbmp", "image/vnd.wap.wbmp"}, _ {"wbmxl", "application/vnd.wap.wbxml"}, _ {"wml", "text/vnd.wap.wml"}, _ {"wmlc", "application/vnd.wap.wmlc"}, _ {"wmls", "text/vnd.wap.wmlscript"}, _ {"wmlsc", "application/vnd.wap.wmlscriptc"}, _ {"wrl", "model/vrml"}, _ {"xbm", "image/x-xbitmap"}, _ {"xht", "application/xhtml+xml"}, _ {"xhtml", "application/xhtml+xml"}, _ {"xls", "application/vnd.ms-excel"}, _ {"xml", "application/xml"}, _ {"xpm", "image/x-xpixmap"}, _ {"xsl", "application/xml"}, _ {"xslt", "application/xslt+xml"}, _ {"xul", "application/vnd.mozilla.xul+xml"}, _ {"xwd", "image/x-xwindowdump"}, _ {"xyz", "chemical/x-xyz"}, _ {"zip", "application/zip"} _ }
我认为正确的答案是史蒂夫·摩根和谢尔盖的答案的结合。 这就是Internet Explorer所做的。 对FindMimeFromData的pinvoke调用FindMimeFromData适用于26种硬编码的MIMEtypes。 此外，即使可能存在更具体，更适当的MIMEtypes，它也会给出不明确的MIMEtypes（如text/plain或application/octet-stream ）。 如果它没有给出一个好的MIMEtypes，你可以到registry中寻找更具体的MIMEtypes。 服务器registry可以有更多最新的MIMEtypes。
请参阅： http : //msdn.microsoft.com/en-us/library/ms775147(VS.85).aspx
这个类使用以前的答案尝试3种不同的方式：基于扩展，FindMimeFromData API和使用registry。
using System; using System.Collections.Generic; using System.IO; using System.Runtime.InteropServices; using Microsoft.Win32; namespace YourNamespace { public static class MimeTypeParser { [DllImport(@"urlmon.dll", CharSet = CharSet.Auto)] private extern static System.UInt32 FindMimeFromData( System.UInt32 pBC, [MarshalAs(UnmanagedType.LPStr)] System.String pwzUrl, [MarshalAs(UnmanagedType.LPArray)] byte[] pBuffer, System.UInt32 cbSize, [MarshalAs(UnmanagedType.LPStr)] System.String pwzMimeProposed, System.UInt32 dwMimeFlags, out System.UInt32 ppwzMimeOut, System.UInt32 dwReserverd ); public static string GetMimeType(string sFilePath) { string sMimeType = GetMimeTypeFromList(sFilePath); if (String.IsNullOrEmpty(sMimeType)) { sMimeType = GetMimeTypeFromFile(sFilePath); if (String.IsNullOrEmpty(sMimeType)) { sMimeType = GetMimeTypeFromRegistry(sFilePath); } } return sMimeType; } public static string GetMimeTypeFromList(string sFileNameOrPath) { string sMimeType = null; string sExtensionWithoutDot = Path.GetExtension(sFileNameOrPath).Substring(1).ToLower(); if (!String.IsNullOrEmpty(sExtensionWithoutDot) && spDicMIMETypes.ContainsKey(sExtensionWithoutDot)) { sMimeType = spDicMIMETypes[sExtensionWithoutDot]; } return sMimeType; } public static string GetMimeTypeFromRegistry(string sFileNameOrPath) { string sMimeType = null; string sExtension = Path.GetExtension(sFileNameOrPath).ToLower(); RegistryKey pKey = Registry.ClassesRoot.OpenSubKey(sExtension); if (pKey != null && pKey.GetValue("Content Type") != null) { sMimeType = pKey.GetValue("Content Type").ToString(); } return sMimeType; } public static string GetMimeTypeFromFile(string sFilePath) { string sMimeType = null; if (File.Exists(sFilePath)) { byte[] abytBuffer = new byte[256]; using (FileStream pFileStream = new FileStream(sFilePath, FileMode.Open)) { if (pFileStream.Length >= 256) { pFileStream.Read(abytBuffer, 0, 256); } else { pFileStream.Read(abytBuffer, 0, (int)pFileStream.Length); } } try { UInt32 unMimeType; FindMimeFromData(0, null, abytBuffer, 256, null, 0, out unMimeType, 0); IntPtr pMimeType = new IntPtr(unMimeType); string sMimeTypeFromFile = Marshal.PtrToStringUni(pMimeType); Marshal.FreeCoTaskMem(pMimeType); if (!String.IsNullOrEmpty(sMimeTypeFromFile) && sMimeTypeFromFile != "text/plain" && sMimeTypeFromFile != "application/octet-stream") { sMimeType = sMimeTypeFromFile; } } catch {} } return sMimeType; } private static readonly Dictionary<string, string> spDicMIMETypes = new Dictionary<string, string> { {"ai", "application/postscript"}, {"aif", "audio/x-aiff"}, {"aifc", "audio/x-aiff"}, {"aiff", "audio/x-aiff"}, {"asc", "text/plain"}, {"atom", "application/atom+xml"}, {"au", "audio/basic"}, {"avi", "video/x-msvideo"}, {"bcpio", "application/x-bcpio"}, {"bin", "application/octet-stream"}, {"bmp", "image/bmp"}, {"cdf", "application/x-netcdf"}, {"cgm", "image/cgm"}, {"class", "application/octet-stream"}, {"cpio", "application/x-cpio"}, {"cpt", "application/mac-compactpro"}, {"csh", "application/x-csh"}, {"css", "text/css"}, {"dcr", "application/x-director"}, {"dif", "video/x-dv"}, {"dir", "application/x-director"}, {"djv", "image/vnd.djvu"}, {"djvu", "image/vnd.djvu"}, {"dll", "application/octet-stream"}, {"dmg", "application/octet-stream"}, {"dms", "application/octet-stream"}, {"doc", "application/msword"}, {"docx","application/vnd.openxmlformats-officedocument.wordprocessingml.document"}, {"dotx", "application/vnd.openxmlformats-officedocument.wordprocessingml.template"}, {"docm","application/vnd.ms-word.document.macroEnabled.12"}, {"dotm","application/vnd.ms-word.template.macroEnabled.12"}, {"dtd", "application/xml-dtd"}, {"dv", "video/x-dv"}, {"dvi", "application/x-dvi"}, {"dxr", "application/x-director"}, {"eps", "application/postscript"}, {"etx", "text/x-setext"}, {"exe", "application/octet-stream"}, {"ez", "application/andrew-inset"}, {"gif", "image/gif"}, {"gram", "application/srgs"}, {"grxml", "application/srgs+xml"}, {"gtar", "application/x-gtar"}, {"hdf", "application/x-hdf"}, {"hqx", "application/mac-binhex40"}, {"htc", "text/x-component"}, {"htm", "text/html"}, {"html", "text/html"}, {"ice", "x-conference/x-cooltalk"}, {"ico", "image/x-icon"}, {"ics", "text/calendar"}, {"ief", "image/ief"}, {"ifb", "text/calendar"}, {"iges", "model/iges"}, {"igs", "model/iges"}, {"jnlp", "application/x-java-jnlp-file"}, {"jp2", "image/jp2"}, {"jpe", "image/jpeg"}, {"jpeg", "image/jpeg"}, {"jpg", "image/jpeg"}, {"js", "application/x-javascript"}, {"kar", "audio/midi"}, {"latex", "application/x-latex"}, {"lha", "application/octet-stream"}, {"lzh", "application/octet-stream"}, {"m3u", "audio/x-mpegurl"}, {"m4a", "audio/mp4a-latm"}, {"m4b", "audio/mp4a-latm"}, {"m4p", "audio/mp4a-latm"}, {"m4u", "video/vnd.mpegurl"}, {"m4v", "video/x-m4v"}, {"mac", "image/x-macpaint"}, {"man", "application/x-troff-man"}, {"mathml", "application/mathml+xml"}, {"me", "application/x-troff-me"}, {"mesh", "model/mesh"}, {"mid", "audio/midi"}, {"midi", "audio/midi"}, {"mif", "application/vnd.mif"}, {"mov", "video/quicktime"}, {"movie", "video/x-sgi-movie"}, {"mp2", "audio/mpeg"}, {"mp3", "audio/mpeg"}, {"mp4", "video/mp4"}, {"mpe", "video/mpeg"}, {"mpeg", "video/mpeg"}, {"mpg", "video/mpeg"}, {"mpga", "audio/mpeg"}, {"ms", "application/x-troff-ms"}, {"msh", "model/mesh"}, {"mxu", "video/vnd.mpegurl"}, {"nc", "application/x-netcdf"}, {"oda", "application/oda"}, {"ogg", "application/ogg"}, {"pbm", "image/x-portable-bitmap"}, {"pct", "image/pict"}, {"pdb", "chemical/x-pdb"}, {"pdf", "application/pdf"}, {"pgm", "image/x-portable-graymap"}, {"pgn", "application/x-chess-pgn"}, {"pic", "image/pict"}, {"pict", "image/pict"}, {"png", "image/png"}, {"pnm", "image/x-portable-anymap"}, {"pnt", "image/x-macpaint"}, {"pntg", "image/x-macpaint"}, {"ppm", "image/x-portable-pixmap"}, {"ppt", "application/vnd.ms-powerpoint"}, {"pptx","application/vnd.openxmlformats-officedocument.presentationml.presentation"}, {"potx","application/vnd.openxmlformats-officedocument.presentationml.template"}, {"ppsx","application/vnd.openxmlformats-officedocument.presentationml.slideshow"}, {"ppam","application/vnd.ms-powerpoint.addin.macroEnabled.12"}, {"pptm","application/vnd.ms-powerpoint.presentation.macroEnabled.12"}, {"potm","application/vnd.ms-powerpoint.template.macroEnabled.12"}, {"ppsm","application/vnd.ms-powerpoint.slideshow.macroEnabled.12"}, {"ps", "application/postscript"}, {"qt", "video/quicktime"}, {"qti", "image/x-quicktime"}, {"qtif", "image/x-quicktime"}, {"ra", "audio/x-pn-realaudio"}, {"ram", "audio/x-pn-realaudio"}, {"ras", "image/x-cmu-raster"}, {"rdf", "application/rdf+xml"}, {"rgb", "image/x-rgb"}, {"rm", "application/vnd.rn-realmedia"}, {"roff", "application/x-troff"}, {"rtf", "text/rtf"}, {"rtx", "text/richtext"}, {"sgm", "text/sgml"}, {"sgml", "text/sgml"}, {"sh", "application/x-sh"}, {"shar", "application/x-shar"}, {"silo", "model/mesh"}, {"sit", "application/x-stuffit"}, {"skd", "application/x-koan"}, {"skm", "application/x-koan"}, {"skp", "application/x-koan"}, {"skt", "application/x-koan"}, {"smi", "application/smil"}, {"smil", "application/smil"}, {"snd", "audio/basic"}, {"so", "application/octet-stream"}, {"spl", "application/x-futuresplash"}, {"src", "application/x-wais-source"}, {"sv4cpio", "application/x-sv4cpio"}, {"sv4crc", "application/x-sv4crc"}, {"svg", "image/svg+xml"}, {"swf", "application/x-shockwave-flash"}, {"t", "application/x-troff"}, {"tar", "application/x-tar"}, {"tcl", "application/x-tcl"}, {"tex", "application/x-tex"}, {"texi", "application/x-texinfo"}, {"texinfo", "application/x-texinfo"}, {"tif", "image/tiff"}, {"tiff", "image/tiff"}, {"tr", "application/x-troff"}, {"tsv", "text/tab-separated-values"}, {"txt", "text/plain"}, {"ustar", "application/x-ustar"}, {"vcd", "application/x-cdlink"}, {"vrml", "model/vrml"}, {"vxml", "application/voicexml+xml"}, {"wav", "audio/x-wav"}, {"wbmp", "image/vnd.wap.wbmp"}, {"wbmxl", "application/vnd.wap.wbxml"}, {"wml", "text/vnd.wap.wml"}, {"wmlc", "application/vnd.wap.wmlc"}, {"wmls", "text/vnd.wap.wmlscript"}, {"wmlsc", "application/vnd.wap.wmlscriptc"}, {"wrl", "model/vrml"}, {"xbm", "image/x-xbitmap"}, {"xht", "application/xhtml+xml"}, {"xhtml", "application/xhtml+xml"}, {"xls", "application/vnd.ms-excel"}, {"xml", "application/xml"}, {"xpm", "image/x-xpixmap"}, {"xsl", "application/xml"}, {"xlsx","application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"}, {"xltx","application/vnd.openxmlformats-officedocument.spreadsheetml.template"}, {"xlsm","application/vnd.ms-excel.sheet.macroEnabled.12"}, {"xltm","application/vnd.ms-excel.template.macroEnabled.12"}, {"xlam","application/vnd.ms-excel.addin.macroEnabled.12"}, {"xlsb","application/vnd.ms-excel.sheet.binary.macroEnabled.12"}, {"xslt", "application/xslt+xml"}, {"xul", "application/vnd.mozilla.xul+xml"}, {"xwd", "image/x-xwindowdump"}, {"xyz", "chemical/x-xyz"}, {"zip", "application/zip"} }; } }
I came across the same issue and eventually opted for my own flavour of Kirk Baucom's solution, found here .
It seems to me that this is an opportunity for someone to write an online look-up service.
Anyway, Hope it helps.
This answer is a copy of the author's answer (Richard Gourlay), but improved to solve issues on IIS 8 / win2012 (where function would cause app pool to crash), based on Rohland's comment pointing to http://www.pinvoke.net/default.aspx/urlmon.findmimefromdata
using System.Runtime.InteropServices;
…
public static string GetMimeFromFile(string filename) { if (!File.Exists(filename)) throw new FileNotFoundException(filename + " not found"); const int maxContent = 256; var buffer = new byte[maxContent]; using (var fs = new FileStream(filename, FileMode.Open)) { if (fs.Length >= maxContent) fs.Read(buffer, 0, maxContent); else fs.Read(buffer, 0, (int) fs.Length); } var mimeTypePtr = IntPtr.Zero; try { var result = FindMimeFromData(IntPtr.Zero, null, buffer, maxContent, null, 0, out mimeTypePtr, 0); if (result != 0) { Marshal.FreeCoTaskMem(mimeTypePtr); throw Marshal.GetExceptionForHR(result); } var mime = Marshal.PtrToStringUni(mimeTypePtr); Marshal.FreeCoTaskMem(mimeTypePtr); return mime; } catch (Exception e) { if (mimeTypePtr != IntPtr.Zero) { Marshal.FreeCoTaskMem(mimeTypePtr); } return "unknown/unknown"; } } [DllImport("urlmon.dll", CharSet = CharSet.Unicode, ExactSpelling = true, SetLastError = false)] private static extern int FindMimeFromData(IntPtr pBC, [MarshalAs(UnmanagedType.LPWStr)] string pwzUrl, [MarshalAs(UnmanagedType.LPArray, ArraySubType = UnmanagedType.I1, SizeParamIndex = 3)] byte[] pBuffer, int cbSize, [MarshalAs(UnmanagedType.LPWStr)] string pwzMimeProposed, int dwMimeFlags, out IntPtr ppwzMimeOut, int dwReserved);
@Steve Morgan and @Richard Gourlay this is a great solution, thank you for that. One small drawback is that when the number of bytes in a file is 255 or below, the mime type will sometimes yield "application/octet-stream", which is slightly inaccurate for files which would be expected to yield "text/plain". I have updated your original method to account for this situation as follows:
If the number of bytes in the file is less than or equal to 255 and the deduced mime type is "application/octet-stream", then create a new byte array that consists of the original file bytes repeated n-times until the total number of bytes is >= 256. Then re-check the mime-type on that new byte array.
Modified method:
Imports System.Runtime.InteropServices <DllImport("urlmon.dll", CharSet:=CharSet.Auto)> _ Private Shared Function FindMimeFromData(pBC As System.UInt32, <MarshalAs(UnmanagedType.LPStr)> pwzUrl As System.String, <MarshalAs(UnmanagedType.LPArray)> pBuffer As Byte(), cbSize As System.UInt32, <MarshalAs(UnmanagedType.LPStr)> pwzMimeProposed As System.String, dwMimeFlags As System.UInt32, _ ByRef ppwzMimeOut As System.UInt32, dwReserverd As System.UInt32) As System.UInt32 End Function Private Function GetMimeType(ByVal f As FileInfo) As String 'See http://stackoverflow.com/questions/58510/using-net-how-can-you-find-the-mime-type-of-a-file-based-on-the-file-signature Dim returnValue As String = "" Dim fileStream As FileStream = Nothing Dim fileStreamLength As Long = 0 Dim fileStreamIsLessThanBByteSize As Boolean = False Const byteSize As Integer = 255 Const bbyteSize As Integer = byteSize + 1 Const ambiguousMimeType As String = "application/octet-stream" Const unknownMimeType As String = "unknown/unknown" Dim buffer As Byte() = New Byte(byteSize) {} Dim fnGetMimeTypeValue As New Func(Of Byte(), Integer, String)( Function(_buffer As Byte(), _bbyteSize As Integer) As String Dim _returnValue As String = "" Dim mimeType As UInt32 = 0 FindMimeFromData(0, Nothing, _buffer, _bbyteSize, Nothing, 0, mimeType, 0) Dim mimeTypePtr As IntPtr = New IntPtr(mimeType) _returnValue = Marshal.PtrToStringUni(mimeTypePtr) Marshal.FreeCoTaskMem(mimeTypePtr) Return _returnValue End Function) If (f.Exists()) Then Try fileStream = New FileStream(f.FullName(), FileMode.Open, FileAccess.Read, FileShare.ReadWrite) fileStreamLength = fileStream.Length() If (fileStreamLength >= bbyteSize) Then fileStream.Read(buffer, 0, bbyteSize) Else fileStreamIsLessThanBByteSize = True fileStream.Read(buffer, 0, CInt(fileStreamLength)) End If returnValue = fnGetMimeTypeValue(buffer, bbyteSize) If (returnValue.Equals(ambiguousMimeType, StringComparison.OrdinalIgnoreCase) AndAlso fileStreamIsLessThanBByteSize AndAlso fileStreamLength > 0) Then 'Duplicate the stream content until the stream length is >= bbyteSize to get a more deterministic mime type analysis. Dim currentBuffer As Byte() = buffer.Take(fileStreamLength).ToArray() Dim repeatCount As Integer = Math.Floor((bbyteSize / fileStreamLength) + 1) Dim bBufferList As List(Of Byte) = New List(Of Byte) While (repeatCount > 0) bBufferList.AddRange(currentBuffer) repeatCount -= 1 End While Dim bbuffer As Byte() = bBufferList.Take(bbyteSize).ToArray() returnValue = fnGetMimeTypeValue(bbuffer, bbyteSize) End If Catch ex As Exception returnValue = unknownMimeType Finally If (fileStream IsNot Nothing) Then fileStream.Close() End Try End If Return returnValue End Function
If someone was up for it they could port the excellent perl module File::Type to .NET. In the code is a set of file header magic number look ups for each file type or regex matches.
Here's a .NET file type detecting library http://filetypedetective.codeplex.com/ but it only detects a smallish number of files at the moment.
IIS 7 or more
Use this code, but you need to be the admin on the server
public bool CheckMimeMapExtension(string fileExtension) { try { using ( ServerManager serverManager = new ServerManager()) { // connects to default app.config var config = serverManager.GetApplicationHostConfiguration(); var staticContent = config.GetSection("system.webServer/staticContent"); var mimeMap = staticContent.GetCollection(); foreach (var mimeType in mimeMap) { if (((String)mimeType["fileExtension"]).Equals(fileExtension, StringComparison.OrdinalIgnoreCase)) return true; } } return false; } catch (Exception ex) { Console.WriteLine("An exception has occurred: \n{0}", ex.Message); Console.Read(); } return false; }
I ended up using Winista MimeDetector from Netomatix. The sources can be downloaded for free after you created an account: http://www.netomatix.com/Products/DocumentManagement/MimeDetector.aspx
MimeTypes g_MimeTypes = new MimeTypes("mime-types.xml"); sbyte [] fileData = null; using (System.IO.FileStream srcFile = new System.IO.FileStream(strFile, System.IO.FileMode.Open)) { byte [] data = new byte[srcFile.Length]; srcFile.Read(data, 0, (Int32)srcFile.Length); fileData = Winista.Mime.SupportUtil.ToSByteArray(data); } MimeType oMimeType = g_MimeTypes.GetMimeType(fileData);
This is part of another question answered here: Alternative to FindMimeFromData method in Urlmon.dll one which has more MIME types The best solution to this problem in my opinion.
When working with Windows Azure Web role or any other host that runs your app in Limited Trust do not forget that you will not be allowed to access registry or unmanaged code. Hybrid approach – combination of try-catch-for-registry and in-memory dictionary looks like a good solution that has a bit of everything.
I use this code to do it :
public class DefaultMimeResolver : IMimeResolver { private readonly IFileRepository _fileRepository; public DefaultMimeResolver(IFileRepository fileRepository) { _fileRepository = fileRepository; } [DllImport(@"urlmon.dll", CharSet = CharSet.Auto)] private static extern System.UInt32 FindMimeFromData( System.UInt32 pBC, [MarshalAs(UnmanagedType.LPStr)] System.String pwzUrl, [MarshalAs(UnmanagedType.LPArray)] byte[] pBuffer, System.UInt32 cbSize, [MarshalAs(UnmanagedType.LPStr)] System.String pwzMimeProposed, System.UInt32 dwMimeFlags, out System.UInt32 ppwzMimeOut, System.UInt32 dwReserverd); public string GetMimeTypeFromFileExtension(string fileExtension) { if (string.IsNullOrEmpty(fileExtension)) { throw new ArgumentNullException("fileExtension"); } string mimeType = GetMimeTypeFromList(fileExtension); if (String.IsNullOrEmpty(mimeType)) { mimeType = GetMimeTypeFromRegistry(fileExtension); } return mimeType; } public string GetMimeTypeFromFile(string filePath) { if (string.IsNullOrEmpty(filePath)) { throw new ArgumentNullException("filePath"); } if (!File.Exists(filePath)) { throw new FileNotFoundException("File not found : ", filePath); } string mimeType = GetMimeTypeFromList(Path.GetExtension(filePath).ToLower()); if (String.IsNullOrEmpty(mimeType)) { mimeType = GetMimeTypeFromRegistry(Path.GetExtension(filePath).ToLower()); if (String.IsNullOrEmpty(mimeType)) { mimeType = GetMimeTypeFromFileInternal(filePath); } } return mimeType; } private string GetMimeTypeFromList(string fileExtension) { string mimeType = null; if (fileExtension.StartsWith(".")) { fileExtension = fileExtension.TrimStart('.'); } if (!String.IsNullOrEmpty(fileExtension) && _mimeTypes.ContainsKey(fileExtension)) { mimeType = _mimeTypes[fileExtension]; } return mimeType; } private string GetMimeTypeFromRegistry(string fileExtension) { string mimeType = null; try { RegistryKey key = Registry.ClassesRoot.OpenSubKey(fileExtension); if (key != null && key.GetValue("Content Type") != null) { mimeType = key.GetValue("Content Type").ToString(); } } catch (Exception) { // Empty. When this code is running in limited mode accessing registry is not allowed. } return mimeType; } private string GetMimeTypeFromFileInternal(string filePath) { string mimeType = null; if (!File.Exists(filePath)) { return null; } byte[] byteBuffer = new byte[256]; using (FileStream fileStream = _fileRepository.Get(filePath)) { if (fileStream.Length >= 256) { fileStream.Read(byteBuffer, 0, 256); } else { fileStream.Read(byteBuffer, 0, (int)fileStream.Length); } } try { UInt32 MimeTypeNum; FindMimeFromData(0, null, byteBuffer, 256, null, 0, out MimeTypeNum, 0); IntPtr mimeTypePtr = new IntPtr(MimeTypeNum); string mimeTypeFromFile = Marshal.PtrToStringUni(mimeTypePtr); Marshal.FreeCoTaskMem(mimeTypePtr); if (!String.IsNullOrEmpty(mimeTypeFromFile) && mimeTypeFromFile != "text/plain" && mimeTypeFromFile != "application/octet-stream") { mimeType = mimeTypeFromFile; } } catch { // Empty. } return mimeType; } private readonly Dictionary<string, string> _mimeTypes = new Dictionary<string, string> { {"ai", "application/postscript"}, {"aif", "audio/x-aiff"}, {"aifc", "audio/x-aiff"}, {"aiff", "audio/x-aiff"}, {"asc", "text/plain"}, {"atom", "application/atom+xml"}, {"au", "audio/basic"}, {"avi", "video/x-msvideo"}, {"bcpio", "application/x-bcpio"}, {"bin", "application/octet-stream"}, {"bmp", "image/bmp"}, {"cdf", "application/x-netcdf"}, {"cgm", "image/cgm"}, {"class", "application/octet-stream"}, {"cpio", "application/x-cpio"}, {"cpt", "application/mac-compactpro"}, {"csh", "application/x-csh"}, {"css", "text/css"}, {"dcr", "application/x-director"}, {"dif", "video/x-dv"}, {"dir", "application/x-director"}, {"djv", "image/vnd.djvu"}, {"djvu", "image/vnd.djvu"}, {"dll", "application/octet-stream"}, {"dmg", "application/octet-stream"}, {"dms", "application/octet-stream"}, {"doc", "application/msword"}, {"docx", "application/vnd.openxmlformats-officedocument.wordprocessingml.document"}, {"dotx", "application/vnd.openxmlformats-officedocument.wordprocessingml.template"}, {"docm", "application/vnd.ms-word.document.macroEnabled.12"}, {"dotm", "application/vnd.ms-word.template.macroEnabled.12"}, {"dtd", "application/xml-dtd"}, {"dv", "video/x-dv"}, {"dvi", "application/x-dvi"}, {"dxr", "application/x-director"}, {"eps", "application/postscript"}, {"etx", "text/x-setext"}, {"exe", "application/octet-stream"}, {"ez", "application/andrew-inset"}, {"gif", "image/gif"}, {"gram", "application/srgs"}, {"grxml", "application/srgs+xml"}, {"gtar", "application/x-gtar"}, {"hdf", "application/x-hdf"}, {"hqx", "application/mac-binhex40"}, {"htc", "text/x-component"}, {"htm", "text/html"}, {"html", "text/html"}, {"ice", "x-conference/x-cooltalk"}, {"ico", "image/x-icon"}, {"ics", "text/calendar"}, {"ief", "image/ief"}, {"ifb", "text/calendar"}, {"iges", "model/iges"}, {"igs", "model/iges"}, {"jnlp", "application/x-java-jnlp-file"}, {"jp2", "image/jp2"}, {"jpe", "image/jpeg"}, {"jpeg", "image/jpeg"}, {"jpg", "image/jpeg"}, {"js", "application/x-javascript"}, {"kar", "audio/midi"}, {"latex", "application/x-latex"}, {"lha", "application/octet-stream"}, {"lzh", "application/octet-stream"}, {"m3u", "audio/x-mpegurl"}, {"m4a", "audio/mp4a-latm"}, {"m4b", "audio/mp4a-latm"}, {"m4p", "audio/mp4a-latm"}, {"m4u", "video/vnd.mpegurl"}, {"m4v", "video/x-m4v"}, {"mac", "image/x-macpaint"}, {"man", "application/x-troff-man"}, {"mathml", "application/mathml+xml"}, {"me", "application/x-troff-me"}, {"mesh", "model/mesh"}, {"mid", "audio/midi"}, {"midi", "audio/midi"}, {"mif", "application/vnd.mif"}, {"mov", "video/quicktime"}, {"movie", "video/x-sgi-movie"}, {"mp2", "audio/mpeg"}, {"mp3", "audio/mpeg"}, {"mp4", "video/mp4"}, {"mpe", "video/mpeg"}, {"mpeg", "video/mpeg"}, {"mpg", "video/mpeg"}, {"mpga", "audio/mpeg"}, {"ms", "application/x-troff-ms"}, {"msh", "model/mesh"}, {"mxu", "video/vnd.mpegurl"}, {"nc", "application/x-netcdf"}, {"oda", "application/oda"}, {"ogg", "application/ogg"}, {"pbm", "image/x-portable-bitmap"}, {"pct", "image/pict"}, {"pdb", "chemical/x-pdb"}, {"pdf", "application/pdf"}, {"pgm", "image/x-portable-graymap"}, {"pgn", "application/x-chess-pgn"}, {"pic", "image/pict"}, {"pict", "image/pict"}, {"png", "image/png"}, {"pnm", "image/x-portable-anymap"}, {"pnt", "image/x-macpaint"}, {"pntg", "image/x-macpaint"}, {"ppm", "image/x-portable-pixmap"}, {"ppt", "application/vnd.ms-powerpoint"}, {"pptx", "application/vnd.openxmlformats-officedocument.presentationml.presentation"}, {"potx", "application/vnd.openxmlformats-officedocument.presentationml.template"}, {"ppsx", "application/vnd.openxmlformats-officedocument.presentationml.slideshow"}, {"ppam", "application/vnd.ms-powerpoint.addin.macroEnabled.12"}, {"pptm", "application/vnd.ms-powerpoint.presentation.macroEnabled.12"}, {"potm", "application/vnd.ms-powerpoint.template.macroEnabled.12"}, {"ppsm", "application/vnd.ms-powerpoint.slideshow.macroEnabled.12"}, {"ps", "application/postscript"}, {"qt", "video/quicktime"}, {"qti", "image/x-quicktime"}, {"qtif", "image/x-quicktime"}, {"ra", "audio/x-pn-realaudio"}, {"ram", "audio/x-pn-realaudio"}, {"ras", "image/x-cmu-raster"}, {"rdf", "application/rdf+xml"}, {"rgb", "image/x-rgb"}, {"rm", "application/vnd.rn-realmedia"}, {"roff", "application/x-troff"}, {"rtf", "text/rtf"}, {"rtx", "text/richtext"}, {"sgm", "text/sgml"}, {"sgml", "text/sgml"}, {"sh", "application/x-sh"}, {"shar", "application/x-shar"}, {"silo", "model/mesh"}, {"sit", "application/x-stuffit"}, {"skd", "application/x-koan"}, {"skm", "application/x-koan"}, {"skp", "application/x-koan"}, {"skt", "application/x-koan"}, {"smi", "application/smil"}, {"smil", "application/smil"}, {"snd", "audio/basic"}, {"so", "application/octet-stream"}, {"spl", "application/x-futuresplash"}, {"src", "application/x-wais-source"}, {"sv4cpio", "application/x-sv4cpio"}, {"sv4crc", "application/x-sv4crc"}, {"svg", "image/svg+xml"}, {"swf", "application/x-shockwave-flash"}, {"t", "application/x-troff"}, {"tar", "application/x-tar"}, {"tcl", "application/x-tcl"}, {"tex", "application/x-tex"}, {"texi", "application/x-texinfo"}, {"texinfo", "application/x-texinfo"}, {"tif", "image/tiff"}, {"tiff", "image/tiff"}, {"tr", "application/x-troff"}, {"tsv", "text/tab-separated-values"}, {"txt", "text/plain"}, {"ustar", "application/x-ustar"}, {"vcd", "application/x-cdlink"}, {"vrml", "model/vrml"}, {"vxml", "application/voicexml+xml"}, {"wav", "audio/x-wav"}, {"wbmp", "image/vnd.wap.wbmp"}, {"wbmxl", "application/vnd.wap.wbxml"}, {"wml", "text/vnd.wap.wml"}, {"wmlc", "application/vnd.wap.wmlc"}, {"wmls", "text/vnd.wap.wmlscript"}, {"wmlsc", "application/vnd.wap.wmlscriptc"}, {"wrl", "model/vrml"}, {"xbm", "image/x-xbitmap"}, {"xht", "application/xhtml+xml"}, {"xhtml", "application/xhtml+xml"}, {"xls", "application/vnd.ms-excel"}, {"xml", "application/xml"}, {"xpm", "image/x-xpixmap"}, {"xsl", "application/xml"}, {"xlsx", "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"}, {"xltx", "application/vnd.openxmlformats-officedocument.spreadsheetml.template"}, {"xlsm", "application/vnd.ms-excel.sheet.macroEnabled.12"}, {"xltm", "application/vnd.ms-excel.template.macroEnabled.12"}, {"xlam", "application/vnd.ms-excel.addin.macroEnabled.12"}, {"xlsb", "application/vnd.ms-excel.sheet.binary.macroEnabled.12"}, {"xslt", "application/xslt+xml"}, {"xul", "application/vnd.mozilla.xul+xml"}, {"xwd", "image/x-xwindowdump"}, {"xyz", "chemical/x-xyz"}, {"zip", "application/zip"} }; }
