'POST / HTTP/1.1\r\nContent-Type: application/json\r\nUser-Agent: PostmanRuntime/7.35.0\r\nAccept: */*\r\nCache-Control: no-cache\r\nPostman-Token: 7cfaa52f-1f6b-418d-afb4-09fcb07e9bd3\r\nHost: 127.0.0.1:8080\r\nAccept-Encoding: gzip, deflate, br\r\nConnection: keep-alive\r\nContent-Length: 30\r\n\r\n{"user":"chunshu","pwd":"123"}'
Content-Type
MediaType，即是Internet Media Type，互联网媒体类型；也叫做MIME类型，在Http协议消息头中，使用Content-Type来表示具体请求中的媒体类型信息。
类型格式：type/subtype(;parameter)? type
主类型，任意的字符串，如text，如果是号代表所有；
subtype 子类型，任意的字符串，如html，如果是号代表所有；
parameter 可选，一些参数，如Accept请求头的q参数， Content-Type的 charset参数。
常见的媒体格式类型如下：
text/html ： HTML格式 text/plain ：纯文本格式 text/xml ： XML格式 image/gif ：gif图片格式 image/jpeg ：jpg图片格式 image/png：png图片格式
以application开头的媒体格式类型：
application/xhtml+xml ：XHTML格式 application/xml ： XML数据格式 application/atom+xml ：Atom XML聚合格式 application/json ： JSON数据格式 application/pdf ：pdf格式 application/msword ： Word文档格式 application/octet-stream ： 二进制流数据（如常见的文件下载） application/x-www-form-urlencoded ： <form encType=””>中默认的encType，form表单数据被编码为key/value格式发送到服务器（表单默认的提交数据的格式）
另外一种常见的媒体格式是上传文件之时使用的：
multipart/form-data ： 需要在表单中进行文件上传时，就需要使用该格式
常遇到下面的几种情况:
服务端需要返回一段普通文本给客户端，Content-Type="text/plain" 服务端需要返回一段HTML代码给客户端 ，Content-Type="text/html" 服务端需要返回一段XML代码给客户端 ，Content-Type="text/xml" 服务端需要返回一段javascript代码给客户端，text/javascript 服务端需要返回一段json串给客户端，application/Json
比较全面的contentType的类型值
文件扩展名 Content-Type(Mime-Type) .*（ 二进制流，不知道下载文件类型） application/octet-stream .tif image/tiff .asp text/asp .asx video/x-ms-asf .au audio/basic .avi video/avi .awf application/vnd.adobe.workflow .biz text/xml .bmp application/x-bmp .bot application/x-bot .cit application/x-cit .class java/* .csi application/x-csi .css text/css .dcd text/xml .dcx application/x-dcx .dib application/x-dib .dll application/x-msdownload .doc application/msword .dot application/msword .drw application/x-drw .dtd text/xml .dwf Model/vnd.dwf .dwf application/x-dwf .etd application/x-ebx .exe application/x-msdownload .gif image/gif .gl2 application/x-gl2 .hrf application/x-hrf .hta application/hta .htc text/x-component .htm text/html .html text/html .htt text/webviewhtml .htx text/html .icb application/x-icb .ico image/x-icon .ico application/x-ico .iff application/x-iff .ig4 application/x-g4 .igs application/x-igs .iii application/x-iphone .img application/x-img .ins application/x-internet-signup .java java/* .jfif image/jpeg .jpe image/jpeg .jpe application/x-jpe .jpeg image/jpeg .jpg image/jpeg .jpg application/x-jpg .js application/x-javascript .jsp text/html .la1 audio/x-liquid-file .mdb application/msaccess .mdb application/x-mdb .mfp application/x-shockwave-flash .mht message/rfc822 .mhtml message/rfc822 .mi application/x-mi .mid audio/mid .midi audio/mid .mil application/x-mil .mml text/xml .mnd audio/x-musicnet-download .mns audio/x-musicnet-stream .mocha application/x-javascript .movie video/x-sgi-movie .mp1 audio/mp1 .mp2 audio/mp2 .mp2v video/mpeg .mp3 audio/mp3 .mp4 video/mpeg4 .mpa video/x-mpg .mpd application/vnd.ms-project .mpe video/x-mpeg .mpeg video/mpg .mpg video/mpg .mpga audio/rn-mpeg .mpp application/vnd.ms-project .mps video/x-mpeg .mpt application/vnd.ms-project .mpv video/mpg .mpv2 video/mpeg .mpw application/vnd.ms-project .mpx application/vnd.ms-project .mtx text/xml .mxp application/x-mmxp .net image/pnetvue .nrf application/x-nrf .nws message/rfc822 .odc text/x-ms-odc .out application/x-out .p10 application/pkcs10 .p12 application/x-pkcs12 .p7b application/x-pkcs7-certificates .p7c application/pkcs7-mime .p7m application/pkcs7-mime .p7r application/x-pkcs7-certreqresp .p7s application/pkcs7-signature .pc5 application/x-pc5 .pci application/x-pci .pcl application/x-pcl .pcx application/x-pcx .pdf application/pdf .pdf application/pdf .pdx application/vnd.adobe.pdx .pfx application/x-pkcs12 .pgl application/x-pgl .pic application/x-pic .pko application/vnd.ms-pki.pko .pl application/x-perl .plg text/html .pls audio/scpls .plt application/x-plt .png image/png .png application/x-png .pot application/vnd.ms-powerpoint .ppa application/vnd.ms-powerpoint .ppm application/x-ppm .pps application/vnd.ms-powerpoint .ppt application/vnd.ms-powerpoint .ppt application/x-ppt .pr application/x-pr .prf application/pics-rules .prn application/x-prn .prt application/x-prt .ps application/x-ps .ps application/postscript .ptn application/x-ptn .pwz application/vnd.ms-powerpoint .r3t text/vnd.rn-realtext3d .ra audio/vnd.rn-realaudio .ram audio/x-pn-realaudio .ras application/x-ras .rat application/rat-file .rdf text/xml .rec application/vnd.rn-recording .red application/x-red .rgb application/x-rgb .rjs application/vnd.rn-realsystem-rjs .rjt application/vnd.rn-realsystem-rjt .rlc application/x-rlc .rle application/x-rle .rm application/vnd.rn-realmedia .rmf application/vnd.adobe.rmf .rmi audio/mid .rmj application/vnd.rn-realsystem-rmj .rmm audio/x-pn-realaudio .rmp application/vnd.rn-rn_music_package .rms application/vnd.rn-realmedia-secure .rmvb application/vnd.rn-realmedia-vbr .rmx application/vnd.rn-realsystem-rmx .rnx application/vnd.rn-realplayer .rp image/vnd.rn-realpix .rpm audio/x-pn-realaudio-plugin .rsml application/vnd.rn-rsml .rt text/vnd.rn-realtext .rtf application/msword .rtf application/x-rtf .rv video/vnd.rn-realvideo .sam application/x-sam .sat application/x-sat .sdp application/sdp .sdw application/x-sdw .sit application/x-stuffit .slb application/x-slb .sld application/x-sld .slk drawing/x-slk .smi application/smil .smil application/smil .smk application/x-smk .snd audio/basic .sol text/plain .sor text/plain .spc application/x-pkcs7-certificates .spl application/futuresplash .spp text/xml .ssm application/streamingmedia .sst application/vnd.ms-pki.certstore .stl application/vnd.ms-pki.stl .stm text/html .sty application/x-sty .svg text/xml .swf application/x-shockwave-flash .tdf application/x-tdf .tg4 application/x-tg4 .tga application/x-tga .tif image/tiff .tif application/x-tif .tiff image/tiff .tld text/xml .top drawing/x-top .torrent application/x-bittorrent .tsd text/xml .txt text/plain .uin application/x-icq .uls text/iuls .vcf text/x-vcard .vda application/x-vda .vdx application/vnd.visio .vml text/xml .vpg application/x-vpeg005 .vsd application/vnd.visio .vsd application/x-vsd .vss application/vnd.visio .vst application/vnd.visio .vst application/x-vst .vsw application/vnd.visio .vsx application/vnd.visio .vtx application/vnd.visio .vxml text/xml .wav audio/wav .wax audio/x-ms-wax .wb1 application/x-wb1 .wb2 application/x-wb2 .wb3 application/x-wb3 .wbmp image/vnd.wap.wbmp .wiz application/msword .wk3 application/x-wk3 .wk4 application/x-wk4 .wkq application/x-wkq .wks application/x-wks .wm video/x-ms-wm .wma audio/x-ms-wma .wmd application/x-ms-wmd .wmf application/x-wmf .wml text/vnd.wap.wml .wmv video/x-ms-wmv .wmx video/x-ms-wmx .wmz application/x-ms-wmz .wp6 application/x-wp6 .wpd application/x-wpd .wpg application/x-wpg .wpl application/vnd.ms-wpl .wq1 application/x-wq1 .wr1 application/x-wr1 .wri application/x-wri .wrk application/x-wrk .ws application/x-ws .ws2 application/x-ws .wsc text/scriptlet .wsdl text/xml .wvx video/x-ms-wvx .xdp application/vnd.adobe.xdp .xdr text/xml .xfd application/vnd.adobe.xfd .xfdf application/vnd.adobe.xfdf .xhtml text/html .xls application/vnd.ms-excel .xls application/x-xls .xlw application/x-xlw .xml text/xml .xpl audio/scpls .xq text/xml .xql text/xml .xquery text/xml .xsd text/xml .xsl text/xml .xslt text/xml .xwd application/x-xwd .x_b application/x-x_b .sis application/vnd.symbian.install .sisx application/vnd.symbian.install .x_t application/x-x_t .ipa application/vnd.iphone .apk application/vnd.android.package-archive .xap application/x-silverlight-app
