什么是 MIME TYPE？

一、首先，我們要了解瀏覽器是如何處理內容的。在瀏覽器中顯示的內容有 HTML、有 XML、有 GIF、還有 Flash ……那么，瀏覽器是如何區(qū)分它們，決定什么內容用什么形式來顯示呢？答案是 MIME Type，也就是該資源的媒體類型。

媒體類型通常是通過 HTTP 協(xié)議，由 Web 服務器告知瀏覽器的，更準確地說，是通過 Content-Type 來表示的，例如:

Content-Type: text/HTML

表示內容是 text/HTML 類型，也就是超文本文件。為什么是“text/HTML”而不是“HTML/text”或者別的什么？MIME Type 不是個人指定的，是經(jīng)過 ietf 組織協(xié)商，以 RFC 的形式作為建議的標準發(fā)布在網(wǎng)上的，大多數(shù)的 Web 服務器和用戶代理都會支持這個規(guī)范 (順便說一句，Email 附件的類型也是通過 MIME Type 指定的)。

通常只有一些在互聯(lián)網(wǎng)上獲得廣泛應用的格式才會獲得一個 MIME Type，如果是某個客戶端自己定義的格式，一般只能以 application/x- 開頭。

XHTML 正是一個獲得廣泛應用的格式，因此，在 RFC 3236 中，說明了 XHTML 格式文件的 MIME Type 應該是 application/xHTML+XML。

當然，處理本地的文件，在沒有人告訴瀏覽器某個文件的 MIME Type 的情況下，瀏覽器也會做一些默認的處理，這可能和你在操作系統(tǒng)中給文件配置的 MIME Type 有關。比如在 Windows 下，打開注冊表的“HKEY_LOCAL_MACHINESOFTWAREClassesMIMEDatabaseContent Type”主鍵，你可以看到所有 MIME Type 的配置信息。

二、在把輸出結果傳送到瀏覽器上的時候，瀏覽器必須啟動適當?shù)膽贸绦騺硖幚磉@個輸出文檔。這可以通過多種類型MIME（多功能網(wǎng)際郵件擴充協(xié)議）來完成。在HTTP中，MIME類型被定義在Content-Type header中。

例如，架設你要傳送一個Microsoft Excel文件到客戶端。那么這時的MIME類型就是“application/vnd.ms-excel”。在大多數(shù)實際情況中，這個文件然后將傳送給Execl來處理（假設我們設定Execl為處理特殊MIME類型的應用程序）。在ASP中，設定MIME類型的方法是通過Response對象的ContentType屬性。


多媒體文件格式MIME

最早的HTTP協(xié)議中，并沒有附加的數(shù)據(jù)類型信息，所有傳送的數(shù)據(jù)都被客戶程序解釋為超文本標記語言HTML 文檔，而為了支持多媒體數(shù)據(jù)類型，HTTP協(xié)議中就使用了附加在文檔之前的MIME數(shù)據(jù)類型信息來標識數(shù)據(jù)類型。

MIME意為多目Internet郵件擴展，它設計的最初目的是為了在發(fā)送電子郵件時附加多媒體數(shù)據(jù)，讓郵件客戶程序能根據(jù)其類型進行處理。然而當它被HTTP協(xié)議支持之后，它的意義就更為顯著了。它使得HTTP傳輸?shù)牟粌H是普通的文本，而變得豐富多彩。

每個MIME類型由兩部分組成，前面是數(shù)據(jù)的大類別，例如聲音audio、圖象image等，后面定義具體的種類。

常見的MIME類型

超文本標記語言文本 .html,.html text/html
普通文本 .txt text/plain
RTF文本 .rtf application/rtf
GIF圖形 .gif image/gif
JPEG圖形 .ipeg,.jpg image/jpeg
au聲音文件 .au audio/basic
MIDI音樂文件 mid,.midi audio/midi,audio/x-midi
RealAudio音樂文件 .ra, .ram audio/x-pn-realaudio
MPEG文件 .mpg,.mpeg video/mpeg
AVI文件 .avi video/x-msvideo
GZIP文件 .gz application/x-gzip
TAR文件 .tar application/x-tar

Internet中有一個專門組織IANA來確認標準的MIME類型，但Internet發(fā)展的太快，很多應用程序等不及IANA來確認他們使用的MIME類型為標準類型。因此他們使用在類別中以x-開頭的方法標識這個類別還沒有成為標準，例如：x-gzip，x-tar等。事實上這些類型運用的很廣泛，已經(jīng)成為了事實標準。只要客戶機和服務器共同承認這個MIME類型，即使它是不標準的類型也沒有關系，客戶程序就能根據(jù)MIME類型，采用具體的處理手段來處理數(shù)據(jù)。而Web服務器和瀏覽器（包括操作系統(tǒng)）中，缺省都設置了標準的和常見的MIME類型，只有對于不常見的 MIME類型，才需要同時設置服務器和客戶瀏覽器，以進行識別。

由于MIME類型與文檔的后綴相關，因此服務器使用文檔的后綴來區(qū)分不同文件的MIME類型，服務器中必須定義文檔后綴和MIME類型之間的對應關系。而客戶程序從服務器上接收數(shù)據(jù)的時候，它只是從服務器接受數(shù)據(jù)流，并不了解文檔的名字，因此服務器必須使用附加信息來告訴客戶程序數(shù)據(jù)的MIME類型。服務器在發(fā)送真正的數(shù)據(jù)之前，就要先發(fā)送標志數(shù)據(jù)的MIME類型的信息，這個信息使用Content-type關鍵字進行定義，例如對于HTML文檔，服務器將首先發(fā)送以下兩行MIME標識信息,這個標識并不是真正的數(shù)據(jù)文件的一部分。

Content-type: text/html

注意，第二行為一個空行，這是必須的，使用這個空行的目的是將MIME信息與真正的數(shù)據(jù)內容分隔開。

MIME (Multipurpose Internet Mail Extensions) 是描述消息內容類型的因特網(wǎng)標準。
MIME 消息能包含文本、圖像、音頻、視頻以及其他應用程序專用的數(shù)據(jù)。
官方的 MIME 信息是由 Internet Engineering Task Force (IETF) 在下面的文檔中提供的：
RFC-822 Standard for ARPA Internet text messages

RFC-2045 MIME Part 1: Format of Internet Message Bodies

RFC-2046 MIME Part 2: Media Types

RFC-2047 MIME Part 3: Header Extensions for Non-ASCII Text

RFC-2048 MIME Part 4: Registration Procedures

RFC-2049 MIME Part 5: Conformance Criteria and Examples

不同的應用程序支持不同的 MIME 類型。

MIME Types
MIME 類型

MIME (Multipurpose Internet Mail Extensions) is an Internet standard for describes message content types.
MIME （ 多用途的網(wǎng)際郵件擴充協(xié)議）是用于描述信息內容類型的國際標準。

MIME messages can contain text, images, audio, video, and other application-specific data.
MIME 信息可以包含文本、圖像、音頻、視頻和其他的應用程序細節(jié)數(shù)據(jù)。

Official MIME info is provided by the Internet Engineering Task Force (IETF) in the following documents:
官方的MIME信息是由internet工程任務組（IETF）中的下列文檔所提供的：

RFC-822 Standard for ARPA Internet text messages [ARPA互連網(wǎng)文本信息標準]
RFC-2045 MIME Part 1: Format of Internet Message Bodies [MIME 第1部分：互聯(lián)網(wǎng)信息主體的格式]
RFC-2046 MIME Part 2: Media Types [MIME 第2部分：多媒體類型]
RFC-2047 MIME Part 3: Header Extensions for Non-ASCII Text [MIME 第3部分：非ASCII文本的頁眉擴展名]
RFC-2048 MIME Part 4: Registration Procedures [MIME 第4部分：注冊程序]
RFC-2049 MIME Part 5: Conformance Criteria and Examples [MIME 第5部分：一致性標準和案例]
Different applications support different MIME types.
不同的應用程序支持不同的MIME類型。

The reference below is a list of MIME types supported by Microsoft Internet Information Server version 5.
微軟IIS5以上版本支持下面關于MIME類型的參數(shù)列表。

MIME Types By Content Type
Content [內容] 類型 中的 MIME 類型

Type/sub-type 類型/二級類型	Extension 擴展名
application/envoy	evy
application/fractals	fif
application/futuresplash	spl
application/hta	hta
application/internet-property-stream	acx
application/mac-binhex40	hqx
application/msword	doc
application/msword	dot
application/octet-stream	*
application/octet-stream	bin
application/octet-stream	class
application/octet-stream	dms
application/octet-stream	exe
application/octet-stream	lha
application/octet-stream	lzh
application/oda	oda
application/olescript	axs
application/pdf	pdf
application/pics-rules	prf
application/pkcs10	p10
application/pkix-crl	crl
application/postscript	ai
application/postscript	eps
application/postscript	ps
application/rtf	rtf
application/set-payment-initiation	setpay
application/set-registration-initiation	setreg
application/vnd.ms-excel	xla
application/vnd.ms-excel	xlc
application/vnd.ms-excel	xlm
application/vnd.ms-excel	xls
application/vnd.ms-excel	xlt
application/vnd.ms-excel	xlw
application/vnd.ms-pkicertstore	sst
application/vnd.ms-pkiseccat	cat
application/vnd.ms-pkistl	stl
application/vnd.ms-powerpoint	pot,
application/vnd.ms-powerpoint	pps
application/vnd.ms-powerpoint	ppt
application/vnd.ms-project	mpp
application/vnd.ms-works	wcm
application/vnd.ms-works	wdb
application/vnd.ms-works	wks
application/vnd.ms-works	wps
application/winhlp	hlp
application/x-bcpio	bcpio
application/x-cdf	cdf
application/x-compress	z
application/x-compressed	tgz
application/x-cpio	cpio
application/x-csh	csh
application/x-director	dcr
application/x-director	dir
application/x-director	dxr
application/x-dvi	dvi
application/x-gtar	gtar
application/x-gzip	gz
application/x-hdf	hdf
application/x-internet-signup	ins
application/x-internet-signup	isp
application/x-iphone	iii
application/x-javascript	js
application/x-latex	latex
application/x-msaccess	mdb
application/x-mscardfile	crd
application/x-msclip	clp
application/x-msdownload	dll
application/x-msmediaview	m13
application/x-msmediaview	m14
application/x-msmediaview	mvb
application/x-msmetafile	wmf
application/x-msmoney	mny
application/x-mspublisher	pub
application/x-msschedule	scd
application/x-msterminal	trm
application/x-mswrite	wri
application/x-netcdf	cdf
application/x-netcdf	nc
application/x-perfmon	pma
application/x-perfmon	pmc
application/x-perfmon	pml
application/x-perfmon	pmr
application/x-perfmon	pmw
application/x-pkcs12	p12
application/x-pkcs12	pfx
application/x-pkcs7-certificates	p7b
application/x-pkcs7-certificates	spc
application/x-pkcs7-certreqresp	p7r
application/x-pkcs7-mime	p7c
application/x-pkcs7-mime	p7m
application/x-pkcs7-signature	p7s
application/x-sh	sh
application/x-shar	shar
application/x-stuffit	sit
application/x-sv4cpio	sv4cpio
application/x-sv4crc	sv4crc
application/x-tar	tar
application/x-tcl	tcl
application/x-tex	tex
application/x-texinfo	texi
application/x-texinfo	texinfo
application/x-troff	roff
application/x-troff	t
application/x-troff	tr
application/x-troff-man	man
application/x-troff-me	me
application/x-troff-ms	ms
application/x-ustar	ustar
application/x-wais-source	src
application/x-x509-ca-cert	cer
application/x-x509-ca-cert	crt
application/x-x509-ca-cert	der
application/ynd.ms-pkipko	pko
application/zip	zip
audio/basic	au
audio/basic	snd
audio/mid	mid
audio/mid	rmi
audio/mpeg	mp3
audio/x-aiff	aif
audio/x-aiff	aifc
audio/x-aiff	aiff
audio/x-mpegurl	m3u
audio/x-pn-realaudio	ra
audio/x-pn-realaudio	ram
audio/x-wav	wav
image/bmp	bmp
image/cis-cod	cod
image/gif	gif
image/ief	ief
image/jpeg	jpe
image/jpeg	jpeg
image/jpeg	jpg
image/pipeg	jfif
image/svg+xml	svg
image/tiff	tif
image/tiff	tiff
image/x-cmu-raster	ras
image/x-cmx	cmx
image/x-icon	ico
image/x-portable-anymap	pnm
image/x-portable-bitmap	pbm
image/x-portable-graymap	pgm
image/x-portable-pixmap	ppm
image/x-rgb	rgb
image/x-xbitmap	xbm
image/x-xpixmap	xpm
image/x-xwindowdump	xwd
message/rfc822	mht
message/rfc822	mhtml
message/rfc822	nws
text/css	css
text/h323	323
text/html	htm
text/html	html
text/html	stm
text/iuls	uls
text/plain	bas
text/plain	c
text/plain	h
text/plain	txt
text/richtext	rtx
text/scriptlet	sct
text/tab-separated-values	tsv
text/webviewhtml	htt
text/x-component	htc
text/x-setext	etx
text/x-vcard	vcf
video/mpeg	mp2
video/mpeg	mpa
video/mpeg	mpe
video/mpeg	mpeg
video/mpeg	mpg
video/mpeg	mpv2
video/quicktime	mov
video/quicktime	qt
video/x-la-asf	lsf
video/x-la-asf	lsx
video/x-ms-asf	asf
video/x-ms-asf	asr
video/x-ms-asf	asx
video/x-msvideo	avi
video/x-sgi-movie	movie
x-world/x-vrml	flr
x-world/x-vrml	vrml
x-world/x-vrml	wrl
x-world/x-vrml	wrz
x-world/x-vrml	xaf
x-world/x-vrml	xof

按照文件擴展名羅列的Mime類型

Extension 擴展名	Type/sub-type 類型/二級類型
	application/octet-stream
323	text/h323
acx	application/internet-property-stream
ai	application/postscript
aif	audio/x-aiff
aifc	audio/x-aiff
aiff	audio/x-aiff
asf	video/x-ms-asf
asr	video/x-ms-asf
asx	video/x-ms-asf
au	audio/basic
avi	video/x-msvideo
axs	application/olescript
bas	text/plain
bcpio	application/x-bcpio
bin	application/octet-stream
bmp	image/bmp
c	text/plain
cat	application/vnd.ms-pkiseccat
cdf	application/x-cdf
cer	application/x-x509-ca-cert
class	application/octet-stream
clp	application/x-msclip
cmx	image/x-cmx
cod	image/cis-cod
cpio	application/x-cpio
crd	application/x-mscardfile
crl	application/pkix-crl
crt	application/x-x509-ca-cert
csh	application/x-csh
css	text/css
dcr	application/x-director
der	application/x-x509-ca-cert
dir	application/x-director
dll	application/x-msdownload
dms	application/octet-stream
doc	application/msword
dot	application/msword
dvi	application/x-dvi
dxr	application/x-director
eps	application/postscript
etx	text/x-setext
evy	application/envoy
exe	application/octet-stream
fif	application/fractals
flr	x-world/x-vrml
gif	image/gif
gtar	application/x-gtar
gz	application/x-gzip
h	text/plain
hdf	application/x-hdf
hlp	application/winhlp
hqx	application/mac-binhex40
hta	application/hta
htc	text/x-component
htm	text/html
html	text/html
htt	text/webviewhtml
ico	image/x-icon
ief	image/ief
iii	application/x-iphone
ins	application/x-internet-signup
isp	application/x-internet-signup
jfif	image/pipeg
jpe	image/jpeg
jpeg	image/jpeg
jpg	image/jpeg
js	application/x-javascript
latex	application/x-latex
lha	application/octet-stream
lsf	video/x-la-asf
lsx	video/x-la-asf
lzh	application/octet-stream
m13	application/x-msmediaview
m14	application/x-msmediaview
m3u	audio/x-mpegurl
man	application/x-troff-man
mdb	application/x-msaccess
me	application/x-troff-me
mht	message/rfc822
mhtml	message/rfc822
mid	audio/mid
mny	application/x-msmoney
mov	video/quicktime
movie	video/x-sgi-movie
mp2	video/mpeg
mp3	audio/mpeg
mpa	video/mpeg
mpe	video/mpeg
mpeg	video/mpeg
mpg	video/mpeg
mpp	application/vnd.ms-project
mpv2	video/mpeg
ms	application/x-troff-ms
mvb	application/x-msmediaview
nws	message/rfc822
oda	application/oda
p10	application/pkcs10
p12	application/x-pkcs12
p7b	application/x-pkcs7-certificates
p7c	application/x-pkcs7-mime
p7m	application/x-pkcs7-mime
p7r	application/x-pkcs7-certreqresp
p7s	application/x-pkcs7-signature
pbm	image/x-portable-bitmap
pdf	application/pdf
pfx	application/x-pkcs12
pgm	image/x-portable-graymap
pko	application/ynd.ms-pkipko
pma	application/x-perfmon
pmc	application/x-perfmon
pml	application/x-perfmon
pmr	application/x-perfmon
pmw	application/x-perfmon
pnm	image/x-portable-anymap
pot,	application/vnd.ms-powerpoint
ppm	image/x-portable-pixmap
pps	application/vnd.ms-powerpoint
ppt	application/vnd.ms-powerpoint
prf	application/pics-rules
ps	application/postscript
pub	application/x-mspublisher
qt	video/quicktime
ra	audio/x-pn-realaudio
ram	audio/x-pn-realaudio
ras	image/x-cmu-raster
rgb	image/x-rgb
rmi	audio/mid
roff	application/x-troff
rtf	application/rtf
rtx	text/richtext
scd	application/x-msschedule
sct	text/scriptlet
setpay	application/set-payment-initiation
setreg	application/set-registration-initiation
sh	application/x-sh
shar	application/x-shar
sit	application/x-stuffit
snd	audio/basic
spc	application/x-pkcs7-certificates
spl	application/futuresplash
src	application/x-wais-source
sst	application/vnd.ms-pkicertstore
stl	application/vnd.ms-pkistl
stm	text/html
svg	image/svg+xml
sv4cpio	application/x-sv4cpio
sv4crc	application/x-sv4crc
t	application/x-troff
tar	application/x-tar
tcl	application/x-tcl
tex	application/x-tex
texi	application/x-texinfo
texinfo	application/x-texinfo
tgz	application/x-compressed
tif	image/tiff
tiff	image/tiff
tr	application/x-troff
trm	application/x-msterminal
tsv	text/tab-separated-values
txt	text/plain
uls	text/iuls
ustar	application/x-ustar
vcf	text/x-vcard
vrml	x-world/x-vrml
wav	audio/x-wav
wcm	application/vnd.ms-works
wdb	application/vnd.ms-works
wks	application/vnd.ms-works
wmf	application/x-msmetafile
wps	application/vnd.ms-works
wri	application/x-mswrite
wrl	x-world/x-vrml
wrz	x-world/x-vrml
xaf	x-world/x-vrml
xbm	image/x-xbitmap
xla	application/vnd.ms-excel
xlc	application/vnd.ms-excel
xlm	application/vnd.ms-excel
xls	application/vnd.ms-excel
xlt	application/vnd.ms-excel
xlw	application/vnd.ms-excel
xof	x-world/x-vrml
xpm	image/x-xpixmap
xwd	image/x-xwindowdump
z	application/x-compress
zip	application/zip

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