使用c的asp.net中的mime类型的扩展

可能重复：
从扩展中获取MIME？

在带有c#的asp.net中，是否有返回Extension的MIME Type的方法？

其中一些如下：

.bm image/bmp 
.bmp image/bmp 
.bmp image/x-windows-bmp 
.boo application/book 
.book application/book 
.boz application/x-bzip2 
.bsh application/x-bsh 
.bz application/x-bzip 
.bz2 application/x-bzip2 
.c text/plain 
.c text/x-c 
.c++ text/plain 
.cat application/vnd.ms-pki.seccat 
.cc text/plain 
.cc text/x-c 
.ccad application/clariscad 
.cco application/x-cocoa 
.cdf application/cdf 
.cdf application/x-cdf 
.cdf application/x-netcdf 
.cer application/pkix-cert 
.cer application/x-x509-ca-cert 
.cha application/x-chat 
.chat application/x-chat 
.class application/java 
.class application/java-byte-code 
.class application/x-java-class 
.com application/octet-stream 
.com text/plain 
.conf text/plain 
.cpio application/x-cpio 
.cpp text/x-c 
.cpt application/mac-compactpro 
.cpt application/x-compactpro 
.cpt application/x-cpt 
.crl application/pkcs-crl 
.crl application/pkix-crl 
.crt application/pkix-cert 
.crt application/x-x509-ca-cert 
.crt application/x-x509-user-cert 
.csh application/x-csh 
.csh text/x-script.csh 
.css text/x-pointplus 
.css text/css 
.cxx text/plain 
.dcr application/x-director 
.deepv application/x-deepv 
.def text/plain 
.der application/x-x509-ca-cert 
.dif video/x-dv 
.dir application/x-director 
.dl video/dl 
.dl video/x-dl 
.doc application/msword 
.docx application/vnd.openxmlformats-officedocument.wordprocessingml.document 
.dot application/msword 
.dp application/commonground 
.drw application/drafting 
.dump application/octet-stream 
.dv video/x-dv 
.dvi application/x-dvi 
.dwf drawing/x-dwf (old) 
.dwf model/vnd.dwf 
.dwg application/acad 
.dwg image/vnd.dwg 
.dwg image/x-dwg 
.dxf application/dxf 
.dxf image/vnd.dwg 
.dxf image/x-dwg 
.dxr application/x-director 
.el text/x-script.elisp 
.elc application/x-bytecode.elisp 
.elc application/x-elc 
.env application/x-envoy 
.eps application/postscript 
.es application/x-esrehber 
.etx text/x-setext 
.evy application/envoy 
.evy application/x-envoy 
.exe application/octet-stream 
.f text/plain 
.f text/x-fortran 
.f77 text/x-fortran 
.f90 text/plain 
.f90 text/x-fortran 
.fdf application/vnd.fdf 
.fif application/fractals 
.fif image/fif 
.fli video/fli 
.fli video/x-fli 
.flo image/florian 
.flx text/vnd.fmi.flexstor 
.fmf video/x-atomic3d-feature 
.for text/plain 
.for text/x-fortran 
.fpx image/vnd.fpx 
.fpx image/vnd.net-fpx 
.frl application/freeloader 
.funk audio/make 
.g text/plain 
.g3 image/g3fax 
.gif image/gif 
.gl video/gl 
.gl video/x-gl 
.gsd audio/x-gsm 
.gsm audio/x-gsm 
.gsp application/x-gsp 
.gss application/x-gss 
.gtar application/x-gtar 
.gz application/x-compressed 
.gz application/x-gzip 
.gzip application/x-gzip 
.gzip multipart/x-gzip 
.h text/plain 
.h text/x-h 
.hdf application/x-hdf 
.help application/x-helpfile 
.hgl application/vnd.hp-hpgl 
.hh text/plain 
.hh text/x-h 
.hlb text/x-script 
.hlp application/hlp 
.hlp application/x-helpfile 
.hlp application/x-winhelp 
.hpg application/vnd.hp-hpgl 
.hpgl application/vnd.hp-hpgl 
.hqx application/binhex 
.hqx application/binhex4 
.hqx application/mac-binhex 
.hqx application/mac-binhex40 
.hqx application/x-binhex40 
.hqx application/x-mac-binhex40 
.hta application/hta 
.htc text/c-component 
.htm text/html 
.html text/html 
.htmls text/html 
.htt text/webviewhtml 
.htx text/html 
.ice x-conference/x-cooltalk 
.ico image/x-icon 
.idc text/plain 
.ief image/ief 
.iefs image/ief 
.iges application/iges 
.iges model/iges 
.igs application/iges 
.igs model/iges 
.ima application/x-ima 
.imap application/x-httpd-imap 
.inf application/inf 
.ins application/x-internett-signup 
.ip application/x-ip2 
.isu video/x-isvideo 
.it audio/it 
.iv application/x-inventor 
.ivr i-world/i-vrml 
.ivy application/x-livescreen 
.jam audio/x-jam 
.jav text/plain 
.jav text/x-java-source 
.java text/plain 
.java text/x-java-source 
.jcm application/x-java-commerce 
.jfif image/jpeg 
.jfif image/pjpeg 
.jfif-tbnl image/jpeg 
.jpe image/jpeg 
.jpe image/pjpeg 
.jpeg image/jpeg 
.jpeg image/pjpeg 
.jpg image/jpeg 
.jpg image/pjpeg 
.jps image/x-jps 
.js application/x-javascript 
.jut image/jutvision 
.kar audio/midi 
.kar music/x-karaoke 
.ksh application/x-ksh 
.ksh text/x-script.ksh 
.la audio/nspaudio 
.la audio/x-nspaudio 
.lam audio/x-liveaudio 
.latex application/x-latex 
.lha application/lha 
.lha application/octet-stream 
.lha application/x-lha 
.lhx application/octet-stream 
.list text/plain 
.lma audio/nspaudio 
.lma audio/x-nspaudio 
.log text/plain 
.lsp application/x-lisp 
.lsp text/x-script.lisp 
.lst text/plain 
.lsx text/x-la-asf 
.ltx application/x-latex 
.lzh application/octet-stream 
.lzh application/x-lzh 
.lzx application/lzx 
.lzx application/octet-stream 
.lzx application/x-lzx 
.m text/plain 
.m text/x-m 
.m1v video/mpeg 
.m2a audio/mpeg 
.m2v video/mpeg 
.m3u audio/x-mpequrl 
.man application/x-troff-man 
.map application/x-navimap 
.mar text/plain 
.mbd application/mbedlet 
.mc$ application/x-magic-cap-package-1.0 
.mcd application/mcad 
.mcd application/x-mathcad 
.mcf image/vasa 
.mcf text/mcf 
.mcp application/netmc 
.me application/x-troff-me 
.mht message/rfc822 
.mhtml message/rfc822 
.mid application/x-midi 
.mid audio/midi 
.mid audio/x-mid 
.mid audio/x-midi 
.mid music/crescendo 
.mid x-music/x-midi 
.midi application/x-midi 
.midi audio/midi 
.midi audio/x-mid 
.midi audio/x-midi 
.midi music/crescendo 
.midi x-music/x-midi 
.mif application/x-frame 
.mif application/x-mif 
.mime message/rfc822 
.mime www/mime 
.mjf audio/x-vnd.audioexplosion.mjuicemediafile 
.mjpg video/x-motion-jpeg 
.mm application/base64 
.mm application/x-meme 
.mme application/base64 
.mod audio/mod 
.mod audio/x-mod 
.moov video/quicktime 
.mov video/quicktime 
.movie video/x-sgi-movie 
.mp2 audio/mpeg 
.mp2 audio/x-mpeg 
.mp2 video/mpeg 
.mp2 video/x-mpeg 
.mp2 video/x-mpeq2a 
.mp3 audio/mpeg3 
.mp3 audio/x-mpeg3 
.mp3 video/mpeg 
.mp3 video/x-mpeg 
.mpa audio/mpeg 
.mpa video/mpeg 
.mpc application/x-project 
.mpe video/mpeg 
.mpeg video/mpeg 
.mpg audio/mpeg 
.mpg video/mpeg 
.mpga audio/mpeg 
.mpp application/vnd.ms-project 
.mpt application/x-project 
.mpv application/x-project 
.mpx application/x-project 
.mrc application/marc 
.ms application/x-troff-ms 
.mv video/x-sgi-movie 
.my audio/make 
.mzz application/x-vnd.audioexplozion.mzz 
.nap image/naplps 
.naplps image/naplps 
.nc application/x-netcdf 
.ncm application/vnd.nokia.configuration-message 
.nif image/x-niff 
.niff image/x-niff 
.nix application/x-mix-transfer 
.nsc application/x-conference 
.nvd application/x-navidoc 
.o application/octet-stream 
.oda application/oda 
.omc application/x-omc 
.omcd application/x-omcdatamaker 
.omcr application/x-omcregerator 
.p text/x-pascal 
.p10 application/pkcs10 
.p10 application/x-pkcs10 
.p12 application/pkcs-12 
.p12 application/x-pkcs12 
.p7a application/x-pkcs7-signature 
.p7c application/pkcs7-mime 
.p7c application/x-pkcs7-mime 
.p7m application/pkcs7-mime 
.p7m application/x-pkcs7-mime 
.p7r application/x-pkcs7-certreqresp 
.p7s application/pkcs7-signature 
.part application/pro_eng 
.pas text/pascal 
.pbm image/x-portable-bitmap 
.pcl application/vnd.hp-pcl 
.pcl application/x-pcl 
.pct image/x-pict 
.pcx image/x-pcx 
.pdb chemical/x-pdb 
.pdf application/pdf 
.pfunk audio/make 
.pfunk audio/make.my.funk 
.pgm image/x-portable-graymap 
.pgm image/x-portalbe-greymap 
.pic image/pict 
.pict image/pict 
.pkg application/x-newton-compatible-pkg 
.pko application/vnd.ms-pik.pko 
.pl text/plain 
.pl text/x-script.perl 
.plx application/x-pixclscript 
.pm image/x-xpixmap 
.pm text/x-script.perl-module 
.pm4 application/x-pagemaker 
.pm5 application/x-pagemaker 
.png image/png 
.png image/x-png 
.pnm application/x-portable-anymap 
.pnm image/x-portable-anymap 
.pot application/mspowerpoint 
.pot application/vnd.ms-powerpoint 
.pov model/x-pov 
.ppa application/vnd.ms-powerpoint 
.ppm image/x-portable-pixmap 
.pps application/mspowerpoint 
.pps application/vnd.ms-powerpoint 
.ppt application/mspowerpoint 
.ppt application/powerpoint 
.ppt application/vnd.ms-powerpoint 
.ppt application/x-ms-powerpoint 
.pptx application/vnd.openxmlformats-officedocument.presentationml.presentation 
.ppz application/mspowerpoint 
.pre application/x-freelance 
.prt application/pro_eng 
.ps application/postscript 
.psd application/octet-stream 
.pvu paleovu/x-pv 
.pwz application/vnd.ms-pwerpoint 
.py text/x-script.python 
.pyc application/x-bytecode.python 
.qcp audio/vnd.qcelp 
.qd3 x-world/x-3dmf 
.qd3d x-world/x-3dmf 
.qif image/x-quicktime 
.qt video/quicktime 
.qtc video/x-qtc 
.qti image/x-quicktime 
.qtif image/x-quicktime 
.ra audio/x-pn-realaudio 
.ra audio/x-pn-realaudio-plugin 
.ra audio/x-realaudio 
.ram audio/x-pn-realaudio 
.ras application/x-cmu-raster 
.ras image/cmu-raster 
.ras image/x-cum-raster 
.rast image/cum-raster 
.rexx text/x-script.rexx 
.rf image/vnd.rn-realmedia 
.rgb image/x-rgb 
.rm application/vnd.rn-realmedia 
.rm audio/x-pn-realaudio 
.rmi audio/mid 
.rmm audio/x-pn-realaudio 
.rmp audio/x-pn-realaudio 
.rmp audio/x-pn-realaudio-plugin 
.rng application/ringing-tones 
.rng application/vnd.nokia.ringing-tone 
.rnx application/vnd.rn-realplayer 
.roff application/x-troff 
.rp image/vnd.rn-realpix 
.rpm audio/x-pn-realaudio-plugin 
.rt text/richtext 
.rt text/vnd.rn-realtext 
.rtf application/rtf 
.rtf application/x-rtf 
.rtf text/richtext 
.rtx application/rtf 
.rtx text/richtext 
.rv video/vnd.rn-realvideo 
.s text/x-asm 
.s3m audio/s3m 
.saveme application/octet-stream 
.sbk application/x-tbook 
.scm application/x-lotusscreencam 
.scm text/x-script.guile 
.scm text/x-script.scheme 
.scm video/x-scm 
.sdml text/plan 
.sdp application/sdp 
.sdp application/x-sdp 
.sdr application/sounder 
.sea application/sea 
.sea application/x-sea 
.set application/set 
.sgm text/sgml 
.sgm text/x-sgml 
.sgml text/sgml 
.sgml text/x-sgml 
.sh application/x-bsh 
.sh application/x-sh 
.sh application/x-shar 
.sh application/x-script.sh 
.shar application/x-bsh 
.shar application/x-shar 
.shtml text/html 
.shtml text/x-server-parsed-html 
.sid audio/x-psid 
.sit application/x-sit 
.sit application/x-stuffit 
.skd application/x-koan 
.skm application/x-koan 
.skp application/x-koan 
.skt application/x-koan 
.sl application/x-seelogo 
.smi application/smil 
.smil application/smil 
.snd audio/basic 
.snd audio/x-adpcm 
.sol application/solids 
.spc application/x-pkcs7-certificates 
.spc text/x-speech 
.spl application/futuresplash 
.spr application/x-sprite 
.spr application/x-sprite 
.sprite application/x-sprite 
.src application/x-wais-source 
.ssi text/x-server-parsed-html 
.ssm application/streamingmedia 
.sst application/vnd.ms-pki.certstore 
.step application/step 
.stl application/sla 
.stl application/vnd.ms-pki.stl 
.stl application/x-navistyle 
.stp application/step 
.sv4cpio application/x-sv4cpio 
.sv4crc application/x-sv4crc 
.svf image/vnd.dwg 
.svf image/x-dwg 
.svr application/x-world 
.svr x-world/x-svr 
.swf application/x-shockwave-flash 
.t application/x-troff 
.talk text/x-speech 
.tar application/x-tar 
.tbk application/toolbook 
.tbk application/x-tbook 
.tcl application/x-tcl 
.tcl text/x-script.tcl 
.tcsh text/x-script.tcsh 
.tex application/x-tex 
.texi application/x-texinfo 
.texinfo application/x-texinfo 
.text application/plain 
.text text/plain 
.tgz application/gnutar 
.tgz application/x-compressed 
.tif image/tiff 
.tif image/x-tiff 
.tiff image/tiff 
.tiff image/x-tiff 
.tr application/x-troff 
.tsi audio/tsp-audio 
.tsp application/dsptype 
.tsp audio/tsplayer 
.tsv text/tab-separated-values 
.turbot image/florian 
.txt text/plain 
.uil text/x-uil 
.uni text/uri-list 
.unis text/uri-list 
.unv application/i-deas 
.uri text/uri-list 
.uris text/uri-list 
.ustar application/x-ustar 
.ustar multipart/x-ustar 
.uu application/octet-stream 
.uu text/x-uuencode 
.uue text/x-uuencode 
.vcd application/x-cdlink 
.vcs text/x-vcalendar 
.vda application/vda 
.vdo video/vdo 
.vew application/groupwise 
.viv video/vivo 
.viv video/vnd.vivo 
.vivo video/vivo 
.vivo video/vnd.vivo 
.vmd application/vocaltec-media-desc 
.vmf application/vocaltec-media-file 
.voc audio/voc 
.voc audio/x-voc 
.vos video/vosaic 
.vox audo/voxware 
.vqe audio/x-twinvq-plugin 
.vqf audio/x-twinvq 
.vql audio/x-twinvq-plugin 
.vrml application/x-vrml 
.vrml model/vrml 
.vrml x-world/x-vrml 
.vrt x-world/x-vrt 
.vsd application/x-visio 
.vst application/x-visio 
.vsw application/x-visio 
.w60 application/wordperfect6.0 
.w61 application/wordperfect6.1 
.w6w application/msword 
.wav audio/wav 
.wav audio/x-wav 
.wb1 application/x-qpro 
.wbmp image/vnd.wap.wbmp 
.web application/vnd.xara 
.wiz application/msword 
.wk1 application/x-123 
.wmf window/metafile 
.wml text/vnd.wap.wml 
.wmlc applciation/vnd.wap.wmlc 
.wmls text/vnd.wap.wmlscript 
.wmlsc application/vnd.wap.wmlscriptc 
.word application/msword 
.wp application/wordperfect 
.wp5 application/wordperfect 
.wp5 application/wordperfect6.0 
.wp6 application/wordperfect 
.wpd application/wordperfect 
.wpd application/x-wpwin 
.wq1 application/x-lotus 
.wri application/mswrite 
.wri application/x-wri 
.wrl application/x-world 
.wrl model/vrml 
.wrl x-world/x-vrml 
.wrz model/vrml 
.wrz x-world/x-vrml 
.wsc text/scriplet 
.wsrc application/x-wais-source 
.wtk application/x-wintalk 
.xbm image/x-xbitmap 
.xbm image/x-xbm 
.xbm image/xbm 
.xdr video/x-amt-demorun 
.xgz xgl/drawing 
.xif image/vnd.xiff 
.xl application/excel 
.xla application/excel 
.xla application/x-excel 
.xla application/x-msexcel 
.xlb application/excel 
.xlb application/vnd.ms-excel 
.xlb application/x-excel 
.xlc application/excel 
.xlc application/vnd.ms-excel 
.xlc application/x-excel 
.xld application/excel 
.xld application/x-excel 
.xlk application/excel 
.xlk application/x-excel 
.xll application/excel 
.xll application/vnd.ms-excel 
.xll application/x-excel 
.xlm application/excel 
.xlm application/vnd.ms-excel 
.xlm application/x-excel 
.xls application/excel 
.xls application/vnd.ms-excel 
.xls application/x-excel 
.xls application/x-msexcel 
.xlsx application/vnd.openxmlformats-officedocument.spreadsheetml.sheet 
.xlt application/excel 
.xlt application/x-excel 
.xlv application/excel 
.xlv application/x-excel 
.xlw application/excel 
.xlw application/vnd.ms-excel 
.xlw application/x-excel 
.xlw application/x-msexcel 
.xm audio/xm 
.xml application/xml 
.xml text/xml 
.xmz xgl/movie 
.xpix application/x-vnd.ls-xpix 
.xpm image/x-xpixmap 
.xpm image/xpm 
.x-png image/png 
.xsr video/x-amt-showrun 
.xwd image/x-xwd 
.xwd image/x-xwindowdump 
.xyz chemical/x-pdb 
.z application/x-compress 
.z application/x-compressed 
.zip application/x-compressed 
.zip application/x-zip-compressed 
.zip application/zip 
.zip multipart/x-zip 
.zoo application/octet-stream 
.zsh text/x-script.zsh 

提前感谢

 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 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";
    }
}