文件格式对应http的Content-Type字段

"doc" = "application/msword"

"bin" = "application/octet-stream"

"dll" = "application/octet-stream"

"exe" = "application/octet-stream"

"pdf" = "application/pdf"

"p7c" = "application/pkcs7-mime"

"ai" = "application/postscript"

"eps" = "application/postscript"

"ps" = "application/postscript"

"rtf" = "application/rtf"

"fdf" = "application/vnd.fdf"

"arj" = "application/x-arj"

"gz" = "application/x-gzip"

"class" = "application/x-java-class"

"js" = "application/x-javascript"

"lzh" = "application/x-lzh"

"lnk" = "application/x-ms-shortcut"

"tar" = "application/x-tar"

"hlp" = "application/x-winhelp"

"cert" = "application/x-x509-ca-cert"

"zip" = "application/zip"

"cab" = "application/x-compressed"

"arj" = "application/x-compressed"

"aif" = "audio/aiff"

"aifc" = "audio/aiff"

"aiff" = "audio/aiff"

"au" = "audio/basic"

"snd" = "audio/basic"

"mid" = "audio/midi"

"rmi" = "audio/midi"

"mp3" = "audio/mpeg"

"vox" = "audio/voxware"

"wav" = "audio/wav"

"ra" = "audio/x-pn-realaudio"

"ram" = "audio/x-pn-realaudio"

"bmp" = "image/bmp"

"gif" = "image/gif"

"jpeg" = "image/jpeg"

"jpg" = "image/jpeg"

"tif" = "image/tiff"

"tiff" = "image/tiff"

"xbm" = "image/xbm"

"wrl" = "model/vrml"

"htm" = "text/html"

"html" = "text/html"

"c" = "text/plain"

"cpp" = "text/plain"

"def" = "text/plain"

"h" = "text/plain"

"txt" = "text/plain"

"rtx" = "text/richtext"

"rtf" = "text/richtext"

"java" = "text/x-java-source"

"css" = "text/css"

"mpeg" = "video/mpeg"

"mpg" = "video/mpeg"

"mpe" = "video/mpeg"

"avi" = "video/msvideo"

"mov" = "video/quicktime"

"qt" = "video/quicktime"

"shtml" = "wwwserver/html-ssi"

"asa" = "wwwserver/isapi"

"asp" = "wwwserver/isapi"

"cfm" = "wwwserver/isapi"

"dbm" = "wwwserver/isapi"

"isa" = "wwwserver/isapi"

"plx" = "wwwserver/isapi"

"url" = "wwwserver/isapi"

"cgi" = "wwwserver/isapi"

"php" = "wwwserver/isapi"

"wcgi" = "wwwserver/isapi"