开发者社区> wuyudong> 正文
阿里云
为了无法计算的价值
打开APP
阿里云APP内打开

MIME简介

简介:
+关注继续查看

MIME(Multipurpose Internet Mail Extensions)多用途互联网邮件扩展类型。是设定某种扩展名的文件用一种应用程序来打开的方式类型,当该扩展名文件被访问的时候,浏览器会自动使 用指定应用程序来打开。多用于指定一些客户端自定义的文件名,以及一些媒体文件打开方式。

背景介绍

多用途互联网邮件扩展,它是一个互联网标准,在1992年最早应用于电子邮件系统,但后来也应用到浏览器。服务器会将它 们发送的多媒体数据的类型告诉浏览器,而通知手段就是说明该多媒体数据的MIME类型,从而让浏览器知道接收到的信息哪些是MP3文件,哪些是 Shockwave文件等等。服务器将MIME标志符放入传送的数据中来告诉浏览器使用哪种插件读取相关文件。

MIME能够支持非ASCII字符、二进制格式附件等多种格式的邮件消息。这个标准被定义在RFC 2045,RFC 2046,RFC 2047,RFC 2048,RFC 2049等RFC中。 由RFC 822转变而来的RFC 2822,规定电子邮件标准并不允许在邮件消息中使用7位ASCII字符集以外的字符。正因如此,一些非英语字符消息和二进制文件,图像,声音等非文字消息都不能在电子邮件中传输。MIME规定了用于表示各种各样的数据类型的符号化方法。

浏览器接收到文件后,会进入插件系统进行查找,查找出哪种插件可以识别读取接收到的文件。如果浏览器不清楚调用哪种插件系统,它可能会告诉用户缺少某插件,或者直接选择某现有插件来试图读取接收到的文件,或者可能会导致系统的崩溃。传输的信息中缺少MIME标识可能导致的情况很难估计,因为某些计算机系统可能不会出现什么故障,但某些计算机可能就会因此而崩溃。

Microsoft公司应用于Windows系统下的浏览器使用ActiveX控件,而不是Netscape插件,这种 浏览器不必象其它浏览器那样依靠MIME的编码。"OBJECT"标签的"CLSID"属性准确地标明了应调用哪种程序来读取接收到的文件,因此浏览器不 必象"EMBED"标签那样选择一种读取程序。正因为如此,你往往会在使用带插件的浏览器时遇到MIME问题,而使用ActiveX控件的浏览器则很少出 现此类麻烦。

正由于上述工作方式的差别也解释了一种现象,不知你是否发现在使用Netscape浏览器播放WAV文件时,浏览器会调 用LiveConnect插件进行播放,而其它浏览器一般都使用通用的QuickTime的播放插件等来进行播放,这是因为Netscape浏览器接收文 件需要读取MIME标识符,以便决定调用哪种程序来读取接收的文件,而服务器设置在Netscape浏览器中播放WAV文件应使用LiveConnect 插件,因此Netscape浏览器接收到WAV格式的文件时必然就会调用LiveConnect插件,但由于其它浏览器不使用这种方式,因此它们都使用系 统默认的播放WAV格式文件的播放器。当然Flash电影文件并不存在这种问题,因为只有Flash播放器才能够正确读取这种格式的文件。

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,假设你要传送一个Microsoft Excel文件到客户端。那么这时的MIME类型就是“excel”。在大多数实际情况中,这个文件然后将传送给Excel来处理(假设我们设定Excel为处理特殊MIME类型的应用程序)。

文件格式

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意为多功能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(通用型):

超文本标记语言文本   .html text/html

xml文档   .xml text/xml

XHTML文档   .xhtml application/xhtml+xml

普通文本   .txt text/plain

RTF文本   .rtf application/rtf

PDF文档   .pdf application/pdf

Microsoft Word文件   .word application/msword

PNG图像   .png image/png

GIF图形   .gif image/gif

JPEG图形   .jpeg,.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

任意的二进制数据   application/octet-stream

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利用了一个事实就是,RFC 822在消息体的内容中做了一点限制:唯一的限制就是只能使用简单的ASCII文本。所以,MIME信息由正常的Internet文本邮件组成,文本邮件 拥有一些特别的符合RFC 822的信息头和格式化过的信息体(用ASCII 的子集来表示的附件)。这些MIME头给出了一种在邮件中表示附件的特别的方法。

信息剖析

一个普通的文本邮件的信息包含一个头部分(To: From: Subject: 等等)和一个体部分(Hello Mr.,等等)。在一个符合MIME的信息中,也包含一个信息头并不奇怪,邮件的各个部分叫做MIME段,每段前也缀以一个特别的头。MIME邮件只是基 于RFC 822邮件的一个扩展,然而它有着自己的RFC规范集。

头字段

MIME头根据在邮件包中的位置,大体上分为MIME信息头和MIME段头。

MIME信息头有:

MIME-Version:

这个头提供了所用MIME的版本号。这个值习惯上为1.0。

Content-Type:

它定义了数据的类型,以便数据能被适当的处理。有效的类型 有:text,image,audio,video,applications,multipart和message。注意任何一个二进制附件都应该被叫 做application/octet- stream。这个头的一些用例为:image/jpg, application/mswork,multipart/mixed,这只是很少的一部分。

Content-Transfer-Encoding:

这是所有头中最重要的一个,因为它说明了对数据所执行的编码方式,客户/MUA 将用它对附件进行解码。对于每个附件,可以使用7bit,8bit,binary ,quoted-printable,base64和custom中的一种编码方式。7bit编码是用在US ASCII字符集上的常用的一种编码方式,也就是,保持它的原样。8bit和binary编码一般不用。对人类可读的标准文本,如果传输要经过对格式有影 响的网关时对其进行保护,可以使用quoted printable 。Base64是一种通用方法,在需要决定使用哪一种编码方法时,它提供了一个不用费脑子的选择;它通常用在二进制,非文本数据上。注意,任何非7bit 数据必须用一种模式编码,这样它就可以通过Internet邮件网关!

Content-ID:

如果Content-Type是message/external-body或multipart/alternative时,这个头就有用了,它超出了本文的范围。

Content-Description:

这是一个可选的头。它是任何信息段内容的自由文本描述。描述必须使用us-ascii码。

Content-Disposition:

一个试验性的头,它用于给客户程序/MUA提供提示,来决定是否在行内显示附件或作为单独的附件。

MIME段头(出现在实际的MIME附件部分的头),除了MIME-Version头,可以拥有以上任何头字段。如果一 个MIME头是信息块的一部分,它将作用于整个信息体。例如,如果Content-Transfer-Encoding显示在信息(指整个信息)头中,它 应用于整个信息体,但是如果它显示在一个MIME段里,它"只能"用于那个段中。

注意:其可以对自动对收到的邮件进行解密。

类型大全

格式前面为后辍名,后面为对应的MIME型(例如:rar application/x-rar-compressed 表示。RAR对应的是application/x-rar-compressed )

{ ".323", "text/h323" },
{ ".3gp", "video/3gpp" },
{ ".aab", "application/x-authoware-bin" },
{ ".aam", "application/x-authoware-map" },
{ ".aas", "application/x-authoware-seg" },
{ ".acx", "application/internet-property-stream" },
{ ".ai", "application/postscript" },
{ ".aif", "audio/x-aiff" },
{ ".aifc", "audio/x-aiff" },
{ ".aiff", "audio/x-aiff" },
{ ".als", "audio/X-Alpha5" },
{ ".amc", "application/x-mpeg" },
{ ".ani", "application/octet-stream" },
{ ".apk", "application/vnd.android.package-archive" },
{ ".asc", "text/plain" },
{ ".asd", "application/astound" },
{ ".asf", "video/x-ms-asf" },
{ ".asn", "application/astound" },
{ ".asp", "application/x-asap" },
{ ".asr", "video/x-ms-asf" },
{ ".asx", "video/x-ms-asf" },
{ ".au", "audio/basic" },
{ ".avb", "application/octet-stream" },
{ ".avi", "video/x-msvideo" },
{ ".awb", "audio/amr-wb" },
{ ".axs", "application/olescript" },
{ ".bas", "text/plain" },
{ ".bcpio", "application/x-bcpio" },
{ ".bin ", "application/octet-stream" },
{ ".bld", "application/bld" },
{ ".bld2", "application/bld2" },
{ ".bmp", "image/bmp" },
{ ".bpk", "application/octet-stream" },
{ ".bz2", "application/x-bzip2" },
{ ".c", "text/plain" },
{ ".cal", "image/x-cals" },
{ ".cat", "application/vnd.ms-pkiseccat" },
{ ".ccn", "application/x-cnc" },
{ ".cco", "application/x-cocoa" },
{ ".cdf", "application/x-cdf" },
{ ".cer", "application/x-x509-ca-cert" },
{ ".cgi", "magnus-internal/cgi" },
{ ".chat", "application/x-chat" },
{ ".class", "application/octet-stream" },
{ ".clp", "application/x-msclip" },
{ ".cmx", "image/x-cmx" },
{ ".co", "application/x-cult3d-object" },
{ ".cod", "image/cis-cod" },
{ ".conf", "text/plain" },
{ ".cpio", "application/x-cpio" },
{ ".cpp", "text/plain" },
{ ".cpt", "application/mac-compactpro" },
{ ".crd", "application/x-mscardfile" },
{ ".crl", "application/pkix-crl" },
{ ".crt", "application/x-x509-ca-cert" },
{ ".csh", "application/x-csh" },
{ ".csm", "chemical/x-csml" },
{ ".csml", "chemical/x-csml" },
{ ".css", "text/css" },
{ ".cur", "application/octet-stream" },
{ ".dcm", "x-lml/x-evm" },
{ ".dcr", "application/x-director" },
{ ".dcx", "image/x-dcx" },
{ ".der", "application/x-x509-ca-cert" },
{ ".dhtml", "text/html" },
{ ".dir", "application/x-director" },
{ ".dll", "application/x-msdownload" },
{ ".dmg", "application/octet-stream" },
{ ".dms", "application/octet-stream" },
{ ".doc", "application/msword" },
{ ".docx", "application/vnd.openxmlformats-officedocument.wordprocessingml.document" },
{ ".dot", "application/msword" },
{ ".dvi", "application/x-dvi" },
{ ".dwf", "drawing/x-dwf" },
{ ".dwg", "application/x-autocad" },
{ ".dxf", "application/x-autocad" },
{ ".dxr", "application/x-director" },
{ ".ebk", "application/x-expandedbook" },
{ ".emb", "chemical/x-embl-dl-nucleotide" },
{ ".embl", "chemical/x-embl-dl-nucleotide" },
{ ".eps", "application/postscript" },
{ ".epub", "application/epub+zip" },
{ ".eri", "image/x-eri" },
{ ".es", "audio/echospeech" },
{ ".esl", "audio/echospeech" },
{ ".etc", "application/x-earthtime" },
{ ".etx", "text/x-setext" },
{ ".evm", "x-lml/x-evm" },
{ ".evy", "application/envoy" },
{ ".exe", "application/octet-stream" },
{ ".fh4", "image/x-freehand" },
{ ".fh5", "image/x-freehand" },
{ ".fhc", "image/x-freehand" },
{ ".fif", "application/fractals" },
{ ".flr", "x-world/x-vrml" },
{ ".flv", "flv-application/octet-stream" },
{ ".fm", "application/x-maker" },
{ ".fpx", "image/x-fpx" },
{ ".fvi", "video/isivideo" },
{ ".gau", "chemical/x-gaussian-input" },
{ ".gca", "application/x-gca-compressed" },
{ ".gdb", "x-lml/x-gdb" },
{ ".gif", "image/gif" },
{ ".gps", "application/x-gps" },
{ ".gtar", "application/x-gtar" },
{ ".gz", "application/x-gzip" },
{ ".h", "text/plain" },
{ ".hdf", "application/x-hdf" },
{ ".hdm", "text/x-hdml" },
{ ".hdml", "text/x-hdml" },
{ ".hlp", "application/winhlp" },
{ ".hqx", "application/mac-binhex40" },
{ ".hta", "application/hta" },
{ ".htc", "text/x-component" },
{ ".htm", "text/html" },
{ ".html", "text/html" },
{ ".hts", "text/html" },
{ ".htt", "text/webviewhtml" },
{ ".ice", "x-conference/x-cooltalk" },
{ ".ico", "image/x-icon" },
{ ".ief", "image/ief" },
{ ".ifm", "image/gif" },
{ ".ifs", "image/ifs" },
{ ".iii", "application/x-iphone" },
{ ".imy", "audio/melody" },
{ ".ins", "application/x-internet-signup" },
{ ".ips", "application/x-ipscript" },
{ ".ipx", "application/x-ipix" },
{ ".isp", "application/x-internet-signup" },
{ ".it", "audio/x-mod" },
{ ".itz", "audio/x-mod" },
{ ".ivr", "i-world/i-vrml" },
{ ".j2k", "image/j2k" },
{ ".jad", "text/vnd.sun.j2me.app-descriptor" },
{ ".jam", "application/x-jam" },
{ ".jar", "application/java-archive" },
{ ".java", "text/plain" },
{ ".jfif", "image/pipeg" },
{ ".jnlp", "application/x-java-jnlp-file" },
{ ".jpe", "image/jpeg" },
{ ".jpeg", "image/jpeg" },
{ ".jpg", "image/jpeg" },
{ ".jpz", "image/jpeg" },
{ ".js", "application/x-javascript" },
{ ".jwc", "application/jwc" },
{ ".kjx", "application/x-kjx" },
{ ".lak", "x-lml/x-lak" },
{ ".latex", "application/x-latex" },
{ ".lcc", "application/fastman" },
{ ".lcl", "application/x-digitalloca" },
{ ".lcr", "application/x-digitalloca" },
{ ".lgh", "application/lgh" },
{ ".lha", "application/octet-stream" },
{ ".lml", "x-lml/x-lml" },
{ ".lmlpack", "x-lml/x-lmlpack" },
{ ".log", "text/plain" },
{ ".lsf", "video/x-la-asf" },
{ ".lsx", "video/x-la-asf" },
{ ".lzh", "application/octet-stream" },
{ ".m13", "application/x-msmediaview" },
{ ".m14", "application/x-msmediaview" },
{ ".m15", "audio/x-mod" },
{ ".m3u", "audio/x-mpegurl" },
{ ".m3url", "audio/x-mpegurl" },
{ ".m4a", "audio/mp4a-latm" },
{ ".m4b", "audio/mp4a-latm" },
{ ".m4p", "audio/mp4a-latm" },
{ ".m4u", "video/vnd.mpegurl" },
{ ".m4v", "video/x-m4v" },
{ ".ma1", "audio/ma1" },
{ ".ma2", "audio/ma2" },
{ ".ma3", "audio/ma3" },
{ ".ma5", "audio/ma5" },
{ ".man", "application/x-troff-man" },
{ ".map", "magnus-internal/imagemap" },
{ ".mbd", "application/mbedlet" },
{ ".mct", "application/x-mascot" },
{ ".mdb", "application/x-msaccess" },
{ ".mdz", "audio/x-mod" },
{ ".me", "application/x-troff-me" },
{ ".mel", "text/x-vmel" },
{ ".mht", "message/rfc822" },
{ ".mhtml", "message/rfc822" },
{ ".mi", "application/x-mif" },
{ ".mid", "audio/mid" },
{ ".midi", "audio/midi" },
{ ".mif", "application/x-mif" },
{ ".mil", "image/x-cals" },
{ ".mio", "audio/x-mio" },
{ ".mmf", "application/x-skt-lbs" },
{ ".mng", "video/x-mng" },
{ ".mny", "application/x-msmoney" },
{ ".moc", "application/x-mocha" },
{ ".mocha", "application/x-mocha" },
{ ".mod", "audio/x-mod" },
{ ".mof", "application/x-yumekara" },
{ ".mol", "chemical/x-mdl-molfile" },
{ ".mop", "chemical/x-mopac-input" },
{ ".mov", "video/quicktime" },
{ ".movie", "video/x-sgi-movie" },
{ ".mp2", "video/mpeg" },
{ ".mp3", "audio/mpeg" },
{ ".mp4", "video/mp4" },
{ ".mpa", "video/mpeg" },
{ ".mpc", "application/vnd.mpohun.certificate" },
{ ".mpe", "video/mpeg" },
{ ".mpeg", "video/mpeg" },
{ ".mpg", "video/mpeg" },
{ ".mpg4", "video/mp4" },
{ ".mpga", "audio/mpeg" },
{ ".mpn", "application/vnd.mophun.application" },
{ ".mpp", "application/vnd.ms-project" },
{ ".mps", "application/x-mapserver" },
{ ".mpv2", "video/mpeg" },
{ ".mrl", "text/x-mrml" },
{ ".mrm", "application/x-mrm" },
{ ".ms", "application/x-troff-ms" },
{ ".msg", "application/vnd.ms-outlook" },
{ ".mts", "application/metastream" },
{ ".mtx", "application/metastream" },
{ ".mtz", "application/metastream" },
{ ".mvb", "application/x-msmediaview" },
{ ".mzv", "application/metastream" },
{ ".nar", "application/zip" },
{ ".nbmp", "image/nbmp" },
{ ".nc", "application/x-netcdf" },
{ ".ndb", "x-lml/x-ndb" },
{ ".ndwn", "application/ndwn" },
{ ".nif", "application/x-nif" },
{ ".nmz", "application/x-scream" },
{ ".nokia-op-logo", "image/vnd.nok-oplogo-color" },
{ ".npx", "application/x-netfpx" },
{ ".nsnd", "audio/nsnd" },
{ ".nva", "application/x-neva1" },
{ ".nws", "message/rfc822" },
{ ".oda", "application/oda" },
{ ".ogg", "audio/ogg" },
{ ".oom", "application/x-AtlasMate-Plugin" },
{ ".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" },
{ ".pac", "audio/x-pac" },
{ ".pae", "audio/x-epac" },
{ ".pan", "application/x-pan" },
{ ".pbm", "image/x-portable-bitmap" },
{ ".pcx", "image/x-pcx" },
{ ".pda", "image/x-pda" },
{ ".pdb", "chemical/x-pdb" },
{ ".pdf", "application/pdf" },
{ ".pfr", "application/font-tdpfr" },
{ ".pfx", "application/x-pkcs12" },
{ ".pgm", "image/x-portable-graymap" },
{ ".pict", "image/x-pict" },
{ ".pko", "application/ynd.ms-pkipko" },
{ ".pm", "application/x-perl" },
{ ".pma", "application/x-perfmon" },
{ ".pmc", "application/x-perfmon" },
{ ".pmd", "application/x-pmd" },
{ ".pml", "application/x-perfmon" },
{ ".pmr", "application/x-perfmon" },
{ ".pmw", "application/x-perfmon" },
{ ".png", "image/png" },
{ ".pnm", "image/x-portable-anymap" },
{ ".pnz", "image/png" },
{ ".pot,", "application/vnd.ms-powerpoint" },
{ ".ppm", "image/x-portable-pixmap" },
{ ".pps", "application/vnd.ms-powerpoint" },
{ ".ppt", "application/vnd.ms-powerpoint" },
{ ".pptx", "application/vnd.openxmlformats-officedocument.presentationml.presentation" },
{ ".pqf", "application/x-cprplayer" },
{ ".pqi", "application/cprplayer" },
{ ".prc", "application/x-prc" },
{ ".prf", "application/pics-rules" },
{ ".prop", "text/plain" },
{ ".proxy", "application/x-ns-proxy-autoconfig" },
{ ".ps", "application/postscript" },
{ ".ptlk", "application/listenup" },
{ ".pub", "application/x-mspublisher" },
{ ".pvx", "video/x-pv-pvx" },
{ ".qcp", "audio/vnd.qcelp" },
{ ".qt", "video/quicktime" },
{ ".qti", "image/x-quicktime" },
{ ".qtif", "image/x-quicktime" },
{ ".r3t", "text/vnd.rn-realtext3d" },
{ ".ra", "audio/x-pn-realaudio" },
{ ".ram", "audio/x-pn-realaudio" },
{ ".rar", "application/octet-stream" },
{ ".ras", "image/x-cmu-raster" },
{ ".rc", "text/plain" },
{ ".rdf", "application/rdf+xml" },
{ ".rf", "image/vnd.rn-realflash" },
{ ".rgb", "image/x-rgb" },
{ ".rlf", "application/x-richlink" },
{ ".rm", "audio/x-pn-realaudio" },
{ ".rmf", "audio/x-rmf" },
{ ".rmi", "audio/mid" },
{ ".rmm", "audio/x-pn-realaudio" },
{ ".rmvb", "audio/x-pn-realaudio" },
{ ".rnx", "application/vnd.rn-realplayer" },
{ ".roff", "application/x-troff" },
{ ".rp", "image/vnd.rn-realpix" },
{ ".rpm", "audio/x-pn-realaudio-plugin" },
{ ".rt", "text/vnd.rn-realtext" },
{ ".rte", "x-lml/x-gps" },
{ ".rtf", "application/rtf" },
{ ".rtg", "application/metastream" },
{ ".rtx", "text/richtext" },
{ ".rv", "video/vnd.rn-realvideo" },
{ ".rwc", "application/x-rogerwilco" },
{ ".s3m", "audio/x-mod" },
{ ".s3z", "audio/x-mod" },
{ ".sca", "application/x-supercard" },
{ ".scd", "application/x-msschedule" },
{ ".sct", "text/scriptlet" },
{ ".sdf", "application/e-score" },
{ ".sea", "application/x-stuffit" },
{ ".setpay", "application/set-payment-initiation" },
{ ".setreg", "application/set-registration-initiation" },
{ ".sgm", "text/x-sgml" },
{ ".sgml", "text/x-sgml" },
{ ".sh", "application/x-sh" },
{ ".shar", "application/x-shar" },
{ ".shtml", "magnus-internal/parsed-html" },
{ ".shw", "application/presentations" },
{ ".si6", "image/si6" },
{ ".si7", "image/vnd.stiwap.sis" },
{ ".si9", "image/vnd.lgtwap.sis" },
{ ".sis", "application/vnd.symbian.install" },
{ ".sit", "application/x-stuffit" },
{ ".skd", "application/x-Koan" },
{ ".skm", "application/x-Koan" },
{ ".skp", "application/x-Koan" },
{ ".skt", "application/x-Koan" },
{ ".slc", "application/x-salsa" },
{ ".smd", "audio/x-smd" },
{ ".smi", "application/smil" },
{ ".smil", "application/smil" },
{ ".smp", "application/studiom" },
{ ".smz", "audio/x-smd" },
{ ".snd", "audio/basic" },
{ ".spc", "application/x-pkcs7-certificates" },
{ ".spl", "application/futuresplash" },
{ ".spr", "application/x-sprite" },
{ ".sprite", "application/x-sprite" },
{ ".sdp", "application/sdp" },
{ ".spt", "application/x-spt" },
{ ".src", "application/x-wais-source" },
{ ".sst", "application/vnd.ms-pkicertstore" },
{ ".stk", "application/hyperstudio" },
{ ".stl", "application/vnd.ms-pkistl" },
{ ".stm", "text/html" },
{ ".svg", "image/svg+xml" },
{ ".sv4cpio", "application/x-sv4cpio" },
{ ".sv4crc", "application/x-sv4crc" },
{ ".svf", "image/vnd" },
{ ".svg", "image/svg+xml" },
{ ".svh", "image/svh" },
{ ".svr", "x-world/x-svr" },
{ ".swf", "application/x-shockwave-flash" },
{ ".swfl", "application/x-shockwave-flash" },
{ ".t", "application/x-troff" },
{ ".tad", "application/octet-stream" },
{ ".talk", "text/x-speech" },
{ ".tar", "application/x-tar" },
{ ".taz", "application/x-tar" },
{ ".tbp", "application/x-timbuktu" },
{ ".tbt", "application/x-timbuktu" },
{ ".tcl", "application/x-tcl" },
{ ".tex", "application/x-tex" },
{ ".texi", "application/x-texinfo" },
{ ".texinfo", "application/x-texinfo" },
{ ".tgz", "application/x-compressed" },
{ ".thm", "application/vnd.eri.thm" },
{ ".tif", "image/tiff" },
{ ".tiff", "image/tiff" },
{ ".tki", "application/x-tkined" },
{ ".tkined", "application/x-tkined" },
{ ".toc", "application/toc" },
{ ".toy", "image/toy" },
{ ".tr", "application/x-troff" },
{ ".trk", "x-lml/x-gps" },
{ ".trm", "application/x-msterminal" },
{ ".tsi", "audio/tsplayer" },
{ ".tsp", "application/dsptype" },
{ ".tsv", "text/tab-separated-values" },
{ ".ttf", "application/octet-stream" },
{ ".ttz", "application/t-time" },
{ ".txt", "text/plain" },
{ ".uls", "text/iuls" },
{ ".ult", "audio/x-mod" },
{ ".ustar", "application/x-ustar" },
{ ".uu", "application/x-uuencode" },
{ ".uue", "application/x-uuencode" },
{ ".vcd", "application/x-cdlink" },
{ ".vcf", "text/x-vcard" },
{ ".vdo", "video/vdo" },
{ ".vib", "audio/vib" },
{ ".viv", "video/vivo" },
{ ".vivo", "video/vivo" },
{ ".vmd", "application/vocaltec-media-desc" },
{ ".vmf", "application/vocaltec-media-file" },
{ ".vmi", "application/x-dreamcast-vms-info" },
{ ".vms", "application/x-dreamcast-vms" },
{ ".vox", "audio/voxware" },
{ ".vqe", "audio/x-twinvq-plugin" },
{ ".vqf", "audio/x-twinvq" },
{ ".vql", "audio/x-twinvq" },
{ ".vre", "x-world/x-vream" },
{ ".vrml", "x-world/x-vrml" },
{ ".vrt", "x-world/x-vrt" },
{ ".vrw", "x-world/x-vream" },
{ ".vts", "workbook/formulaone" },
{ ".wav", "audio/x-wav" },
{ ".wax", "audio/x-ms-wax" },
{ ".wbmp", "image/vnd.wap.wbmp" },
{ ".wcm", "application/vnd.ms-works" },
{ ".wdb", "application/vnd.ms-works" },
{ ".web", "application/vnd.xara" },
{ ".wi", "image/wavelet" },
{ ".wis", "application/x-InstallShield" },
{ ".wks", "application/vnd.ms-works" },
{ ".wm", "video/x-ms-wm" },
{ ".wma", "audio/x-ms-wma" },
{ ".wmd", "application/x-ms-wmd" },
{ ".wmf", "application/x-msmetafile" },
{ ".wml", "text/vnd.wap.wml" },
{ ".wmlc", "application/vnd.wap.wmlc" },
{ ".wmls", "text/vnd.wap.wmlscript" },
{ ".wmlsc", "application/vnd.wap.wmlscriptc" },
{ ".wmlscript", "text/vnd.wap.wmlscript" },
{ ".wmv", "audio/x-ms-wmv" },
{ ".wmx", "video/x-ms-wmx" },
{ ".wmz", "application/x-ms-wmz" },
{ ".wpng", "image/x-up-wpng" },
{ ".wps", "application/vnd.ms-works" },
{ ".wpt", "x-lml/x-gps" },
{ ".wri", "application/x-mswrite" },
{ ".wrl", "x-world/x-vrml" },
{ ".wrz", "x-world/x-vrml" },
{ ".ws", "text/vnd.wap.wmlscript" },
{ ".wsc", "application/vnd.wap.wmlscriptc" },
{ ".wv", "video/wavelet" },
{ ".wvx", "video/x-ms-wvx" },
{ ".wxl", "application/x-wxl" },
{ ".x-gzip", "application/x-gzip" },
{ ".xaf", "x-world/x-vrml" },
{ ".xar", "application/vnd.xara" },
{ ".xbm", "image/x-xbitmap" },
{ ".xdm", "application/x-xdma" },
{ ".xdma", "application/x-xdma" },
{ ".xdw", "application/vnd.fujixerox.docuworks" },
{ ".xht", "application/xhtml+xml" },
{ ".xhtm", "application/xhtml+xml" },
{ ".xhtml", "application/xhtml+xml" },
{ ".xla", "application/vnd.ms-excel" },
{ ".xlc", "application/vnd.ms-excel" },
{ ".xll", "application/x-excel" },
{ ".xlm", "application/vnd.ms-excel" },
{ ".xls", "application/vnd.ms-excel" },
{ ".xlsx", "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet" },
{ ".xlt", "application/vnd.ms-excel" },
{ ".xlw", "application/vnd.ms-excel" },
{ ".xm", "audio/x-mod" },
{ ".xml", "text/plain" },
{ ".xmz", "audio/x-mod" },
{ ".xof", "x-world/x-vrml" },
{ ".xpi", "application/x-xpinstall" },
{ ".xpm", "image/x-xpixmap" },
{ ".xsit", "text/xml" },
{ ".xsl", "text/xml" },
{ ".xul", "text/xul" },
{ ".xwd", "image/x-xwindowdump" },
{ ".xyz", "chemical/x-pdb" },
{ ".yz1", "application/x-yz1" },
{ ".z", "application/x-compress" },
{ ".zac", "application/x-zaurus-zac" },
{ ".zip", "application/zip" },
{ ".json", "application/json" },

传输编码

内容传输编码(Content-Transfer-Encoding),这个区域使指定ASCII以外的字符编码方式成为可能。形式如下:
Content-Transfer-Encoding: [mechanism]
其中,mechanism的值可以指定为“7bit”,“8bit”,“binary”,“quoted-printable”,“base64”。
7bit
7bit这里指的是7位的ASCII编码方式。
8bit
8位元ASCII码。
binary
quoted-printable
因为欧洲的一些文字和ASCII字符集中的某些字符有部分相同。如果邮件消息使用的是这些语言的话,于ASCII重 叠的那些字符可以原样使用,ASCII字符集中不存在的字符采用形如“=??”的方法编码。这里“??”需要用将字符编码后的16进制数字来指定。采用 quoted-printable编码的消息,长度不会变得太长,而且大部分都是ASCII中的字符,即使不通过解码也大致可以读懂消息的内容。
base64
base64是一种将二进制的01序列转化成ASCII字符的编码方法。编码后的文本或者二进制消息,就可以运用SMTP等只支持ASCII字符的协议传送了。Base64一般被认为会平均增加33%的报文长度,而且,经过编码的消息对于人类来说是不可读的。
x-encodingname
这个值是预留的扩展。

版权声明:本文内容由阿里云实名注册用户自发贡献,版权归原作者所有,阿里云开发者社区不拥有其著作权,亦不承担相应法律责任。具体规则请查看《阿里云开发者社区用户服务协议》和《阿里云开发者社区知识产权保护指引》。如果您发现本社区中有涉嫌抄袭的内容,填写侵权投诉表单进行举报,一经查实,本社区将立刻删除涉嫌侵权内容。

相关文章
ONNX简介
Open Neural Network Exchange(ONNX,开放神经网络交换)格式,是一个用于表示深度学习模型的标准,可使模型在不同框架之间进行转移。
56 0
Shiro(一):shiro简介
Shiro(一):shiro简介
36 0
shiro简介
shiro是apache提供的强大而灵活的开源安全框架,它主要用来处理身份认证,授权,企业会话管理和加密。 通俗的讲,shiro的身份认证和授权就是拦截用户未登陆或者没有相应权限的越权访问。 Shiro的企业会话管理实际就是session管理,shiro的session管理可以自定义Session存储的方式,保存到内存、文件、数据库都可以,与传统tomcat等容器无关。
50 0
Speex手册----Speex 简介
文档分为几部分,第2节介绍Speex的特性以及一些文档中用到的基本术语。第4节是关于Speex提供的标准命令行工具。第5节是使用libspeex API进行编程的详细说明。第7节是一些关于Speex相关标准的信息。
1718 0
MD5简介
MD5简介 所谓MD5,即"Message-Digest Algorithm 5(信息-摘要算法)",它由MD2、MD3、MD4发展而来的一种单向函数算法(也就是HASH算法),它是国际著名的公钥加密算法标准RSA的第一设计者R.Rivest于上个世纪90年代初开发出来的。
738 0
+关注
wuyudong
我的个人博客地址:http://wuyudong.com/
203
文章
0
问答
文章排行榜
最热
最新
相关电子书
更多
低代码开发师(初级)实战教程
立即下载
阿里巴巴DevOps 最佳实践手册
立即下载
冬季实战营第三期:MySQL数据库进阶实战
立即下载