PHP根据文件后缀名得到MIMETYPE

<?
function get_ext_mime($ext){
  $extensions = array(
      "ai"  =>  "application/postscript",
     "aif"  =>  "audio/x-aiff",
    "aifc"  =>  "audio/x-aiff",
    "aiff"  =>  "audio/x-aiff",
     "asc"  =>  "text/plain",
      "au"  =>  "audio/basic",
     "avi"  =>  "video/x-msvideo",
   "bcpio"  =>  "application/x-bcpio",
     "bin"  =>  "application/octet-stream",
       "c"  =>  "text/plain",
      "cc"  =>  "text/plain",
      "py"  =>  "text/plain",
     "php"  =>  "text/plain",
    "ccad"  =>  "application/clariscad",
     "cdf"  =>  "application/x-netcdf",
   "class"  =>  "application/octet-stream",
    "cpio"  =>  "application/x-cpio",
     "cpt"  =>  "application/mac-compactpro",
     "csh"  =>  "application/x-csh",
     "css"  =>  "text/css",
     "dcr"  =>  "application/x-director",
     "dir"  =>  "application/x-director",
     "dms"  =>  "application/octet-stream",
     "doc"  =>  "application/msword",
     "drw"  =>  "application/drafting",
     "dvi"  =>  "application/x-dvi",
     "dwg"  =>  "application/acad",
     "dxf"  =>  "application/dxf",
     "dxr"  =>  "application/x-director",
     "eps"  =>  "application/postscript",
     "etx"  =>  "text/x-setext",
     "exe"  =>  "application/octet-stream",
      "ez"  =>  "application/andrew-inset",
       "f"  =>  "text/plain",
     "f90"  =>  "text/plain",
     "fli"  =>  "video/x-fli",
     "gif"  =>  "image/gif",
    "gtar"  =>  "application/x-gtar",
      "gz"  =>  "application/x-gzip",
       "h"  =>  "text/plain",
     "hdf"  =>  "application/x-hdf",
      "hh"  =>  "text/plain",
     "hqx"  =>  "application/mac-binhex40",
     "htm"  =>  "text/html",
    "html"  =>  "text/html",
     "ice"  =>  "x-conference/x-cooltalk",
     "ief"  =>  "image/ief",
    "iges"  =>  "model/iges",
     "igs"  =>  "model/iges",
     "ips"  =>  "application/x-ipscript",
     "ipx"  =>  "application/x-ipix",
     "jpe"  =>  "image/jpeg",
    "jpeg"  =>  "image/jpeg",
     "jpg"  =>  "image/jpeg",
      "js"  =>  "application/x-javascript",
     "kar"  =>  "audio/midi",
   "latex"  =>  "application/x-latex",
     "lha"  =>  "application/octet-stream",
     "lsp"  =>  "application/x-lisp",
     "lzh"  =>  "application/octet-stream",
       "m"  =>  "text/plain",
     "man"  =>  "application/x-troff-man",
      "me"  =>  "application/x-troff-me",
    "mesh"  =>  "model/mesh",
     "mid"  =>  "audio/midi",
    "midi"  =>  "audio/midi",
     "mif"  =>  "application/vnd.mif",
    "mime"  =>  "www/mime",
     "mov"  =>  "video/quicktime",
   "movie"  =>  "video/x-sgi-movie",
     "mp2"  =>  "audio/mpeg",
     "mp3"  =>  "audio/mpeg",
     "mpe"  =>  "video/mpeg",
    "mpeg"  =>  "video/mpeg",
     "mpg"  =>  "video/mpeg",
    "mpga"  =>  "audio/mpeg",
      "ms"  =>  "application/x-troff-ms",
     "msh"  =>  "model/mesh",
      "nc"  =>  "application/x-netcdf",
     "oda"  =>  "application/oda",
     "pbm"  =>  "image/x-portable-bitmap",
     "pdb"  =>  "chemical/x-pdb",
     "pdf"  =>  "application/pdf",
     "pgm"  =>  "image/x-portable-graymap",
     "pgn"  =>  "application/x-chess-pgn",
     "png"  =>  "image/png",
     "pnm"  =>  "image/x-portable-anymap",
     "pot"  =>  "application/mspowerpoint",
     "ppm"  =>  "image/x-portable-pixmap",
     "pps"  =>  "application/mspowerpoint",
     "ppt"  =>  "application/mspowerpoint",
     "ppz"  =>  "application/mspowerpoint",
     "pre"  =>  "application/x-freelance",
     "prt"  =>  "application/pro_eng",
      "ps"  =>  "application/postscript",
      "qt"  =>  "video/quicktime",
      "ra"  =>  "audio/x-realaudio",
     "ram"  =>  "audio/x-pn-realaudio",
     "ras"  =>  "image/cmu-raster",
     "rgb"  =>  "image/x-rgb",
      "rm"  =>  "audio/x-pn-realaudio",
    "roff"  =>  "application/x-troff",
     "rpm"  =>  "audio/x-pn-realaudio-plugin",
     "rtf"  =>  "text/rtf",
     "rtx"  =>  "text/richtext",
     "scm"  =>  "application/x-lotusscreencam",
     "set"  =>  "application/set",
     "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",
     "sol"  =>  "application/solids",
     "spl"  =>  "application/x-futuresplash",
     "src"  =>  "application/x-wais-source",
    "step"  =>  "application/STEP",
     "stl"  =>  "application/SLA",
     "stp"  =>  "application/STEP",
 "sv4cpio"  =>  "application/x-sv4cpio",
  "sv4crc"  =>  "application/x-sv4crc",
     "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",
     "tsi"  =>  "audio/TSP-audio",
     "tsp"  =>  "application/dsptype",
     "tsv"  =>  "text/tab-separated-values",
     "txt"  =>  "text/plain",
     "unv"  =>  "application/i-deas",
   "ustar"  =>  "application/x-ustar",
     "vcd"  =>  "application/x-cdlink",
     "vda"  =>  "application/vda",
     "viv"  =>  "video/vnd.vivo",
    "vivo"  =>  "video/vnd.vivo",
    "vrml"  =>  "model/vrml",
     "wav"  =>  "audio/x-wav",
     "wrl"  =>  "model/vrml",
     "xbm"  =>  "image/x-xbitmap",
     "xlc"  =>  "application/vnd.ms-excel",
     "xll"  =>  "application/vnd.ms-excel",
     "xlm"  =>  "application/vnd.ms-excel",
     "xls"  =>  "application/vnd.ms-excel",
     "xlw"  =>  "application/vnd.ms-excel",
     "xml"  =>  "text/xml",
     "xpm"  =>  "image/x-xpixmap",
     "xwd"  =>  "image/x-xwindowdump",
     "xyz"  =>  "chemical/x-pdb",
     "zip"  =>  "application/zip"
  );
  $ext = strtolower($ext);
  $mime_type = $extensions[$ext];
  return $mime_type;
}