什么是 MIME TYPE？

一、首先，我们要了解浏览器是如何处理内容的。在浏览器中显示的内容有 HTML、有 XML、有 GIF、还有 Flash ……那么，浏览器是如何区分它们，决定什么内容用什么形式来显示呢？答案是 MIME Type，也就是该资源的媒体类型。

媒体类型通常是通过 HTTP 协议，由 Web 服务器告知浏览器的，更准确地说，是通过 Content-Type 来表示的，例如:

Content-Type: text/HTML

表示内容是 text/HTML 类型，也就是超文本文件。为什么是“text/HTML”而不是“HTML/text”或者别的什么？MIME Type 不是个人指定的，是经过 ietf 组织协商，以 RFC 的形式作为建议的标准发布在网上的，大多数的 Web 服务器和用户代理都会支持这个规范 (顺便说一句，Email 附件的类型也是通过 MIME Type 指定的)。

通常只有一些在互联网上获得广泛应用的格式才会获得一个 MIME Type，如果是某个客户端自己定义的格式，一般只能以 application/x- 开头。

XHTML 正是一个获得广泛应用的格式，因此，在 RFC 3236 中，说明了 XHTML 格式文件的 MIME Type 应该是 application/xHTML+XML。

当然，处理本地的文件，在没有人告诉浏览器某个文件的 MIME Type 的情况下，浏览器也会做一些默认的处理，这可能和你在操作系统中给文件配置的 MIME Type 有关。比如在 Windows 下，打开注册表的“HKEY_LOCAL_MACHINESOFTWAREClassesMIMEDatabaseContent Type”主键，你可以看到所有 MIME Type 的配置信息。

二、在把输出结果传送到浏览器上的时候，浏览器必须启动适当的应用程序来处理这个输出文档。这可以通过多种类型MIME（多功能网际邮件扩充协议）来完成。在HTTP中，MIME类型被定义在Content-Type header中。

例如，架设你要传送一个Microsoft Excel文件到客户端。那么这时的MIME类型就是“application/vnd.ms-excel”。在大多数实际情况中，这个文件然后将传送给Execl来处理（假设我们设定Execl为处理特殊MIME类型的应用程序）。在ASP中，设定MIME类型的方法是通过Response对象的ContentType属性。


多媒体文件格式MIME

最早的HTTP协议中，并没有附加的数据类型信息，所有传送的数据都被客户程序解释为超文本标记语言HTML 文档，而为了支持多媒体数据类型，HTTP协议中就使用了附加在文档之前的MIME数据类型信息来标识数据类型。

MIME意为多目Internet邮件扩展，它设计的最初目的是为了在发送电子邮件时附加多媒体数据，让邮件客户程序能根据其类型进行处理。然而当它被HTTP协议支持之后，它的意义就更为显著了。它使得HTTP传输的不仅是普通的文本，而变得丰富多彩。

每个MIME类型由两部分组成，前面是数据的大类别，例如声音audio、图象image等，后面定义具体的种类。

常见的MIME类型

超文本标记语言文本 .html,.html text/html
普通文本 .txt text/plain
RTF文本 .rtf application/rtf
GIF图形 .gif image/gif
JPEG图形 .ipeg,.jpg image/jpeg
au声音文件 .au audio/basic
MIDI音乐文件 mid,.midi audio/midi,audio/x-midi
RealAudio音乐文件 .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中有一个专门组织IANA来确认标准的MIME类型，但Internet发展的太快，很多应用程序等不及IANA来确认他们使用的MIME类型为标准类型。因此他们使用在类别中以x-开头的方法标识这个类别还没有成为标准，例如：x-gzip，x-tar等。事实上这些类型运用的很广泛，已经成为了事实标准。只要客户机和服务器共同承认这个MIME类型，即使它是不标准的类型也没有关系，客户程序就能根据MIME类型，采用具体的处理手段来处理数据。而Web服务器和浏览器（包括操作系统）中，缺省都设置了标准的和常见的MIME类型，只有对于不常见的 MIME类型，才需要同时设置服务器和客户浏览器，以进行识别。

由于MIME类型与文档的后缀相关，因此服务器使用文档的后缀来区分不同文件的MIME类型，服务器中必须定义文档后缀和MIME类型之间的对应关系。而客户程序从服务器上接收数据的时候，它只是从服务器接受数据流，并不了解文档的名字，因此服务器必须使用附加信息来告诉客户程序数据的MIME类型。服务器在发送真正的数据之前，就要先发送标志数据的MIME类型的信息，这个信息使用Content-type关键字进行定义，例如对于HTML文档，服务器将首先发送以下两行MIME标识信息,这个标识并不是真正的数据文件的一部分。

Content-type: text/html

注意，第二行为一个空行，这是必须的，使用这个空行的目的是将MIME信息与真正的数据内容分隔开。

MIME (Multipurpose Internet Mail Extensions) 是描述消息内容类型的因特网标准。
MIME 消息能包含文本、图像、音频、视频以及其他应用程序专用的数据。
官方的 MIME 信息是由 Internet Engineering Task Force (IETF) 在下面的文档中提供的：
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

不同的应用程序支持不同的 MIME 类型。

MIME Types
MIME 类型

MIME (Multipurpose Internet Mail Extensions) is an Internet standard for describes message content types.
MIME （ 多用途的网际邮件扩充协议）是用于描述信息内容类型的国际标准。

MIME messages can contain text, images, audio, video, and other application-specific data.
MIME 信息可以包含文本、图像、音频、视频和其他的应用程序细节数据。

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工程任务组（IETF）中的下列文档所提供的：

RFC-822 Standard for ARPA Internet text messages [ARPA互连网文本信息标准]
RFC-2045 MIME Part 1: Format of Internet Message Bodies [MIME 第1部分：互联网信息主体的格式]
RFC-2046 MIME Part 2: Media Types [MIME 第2部分：多媒体类型]
RFC-2047 MIME Part 3: Header Extensions for Non-ASCII Text [MIME 第3部分：非ASCII文本的页眉扩展名]
RFC-2048 MIME Part 4: Registration Procedures [MIME 第4部分：注册程序]
RFC-2049 MIME Part 5: Conformance Criteria and Examples [MIME 第5部分：一致性标准和案例]
Different applications support different MIME types.
不同的应用程序支持不同的MIME类型。

The reference below is a list of MIME types supported by Microsoft Internet Information Server version 5.
微软IIS5以上版本支持下面关于MIME类型的参数列表。

MIME Types By Content Type
Content [内容] 类型 中的 MIME 类型

Type/sub-type
类型/二级类型 Extension
扩展名 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

按照文件扩展名罗列的Mime类型

Extension
扩展名 Type/sub-type
类型/二级类型   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