response.setContentType(MIME)的作用是使客户端的浏览器区分不同种类的数据，并根据不同的MIME调用浏览器内不同的程序嵌入模块来处理相应的数据。
一、什么是MIME
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。
它是一个互联网标准，扩展了电子邮件标准，使其能够支持：
非ASCII字符文本；非文本格式附件（二进制、声音、图像等）；由多部分（multiple parts）组成的消息体；包含非ASCII字符的头信息（Header information）。
这个标准被定义在RFC 2045、RFC 2046、RFC 2047、RFC 2048、RFC 2049等RFC中。 MIME改善了由RFC 822转变而来的RFC 2822，这些旧标准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，声音等非文字消息原本都不能在电子邮件中传输(MIME可以)。MIME规定了用于表示各种各样的数据类型的符号化方法。 此外，在万维网中使用的HTTP协议中也使用了MIME的框架，标准被扩展为互联网媒体类型。
二、MIME的作用
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，并不了解文档的类型，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信息头比较常用的两个：
Content-Type:(常用，该实体头的作用是让服务器告诉浏览器它发送的数据属于什么文件类型)
Content-Disposition: (常用，当Content-Type 的类型为要下载的类型时 , 这个信息头会告诉浏览器这个文件的名字和类型)
//头部信息设置如下
response.addHeader("content-type","image/png");
response.addHeader("Content-Disposition", "attachment;filename="+filename);
三、MIME类型大全
//格式前面为后辍名，后面为对应的MIME型。
//常用的类型
{".json", "application/json" },
{".apk", "application/vnd.android.package-archive" },
{".avi", "video/x-msvideo" },
{ ".bin", "application/octet-stream" },
{".bmp", "image/bmp" },
{".gif", "image/gif" },
{".jpe", "image/jpeg" },
{".jpeg", "image/jpeg" },
{".jpg", "image/jpeg" },
{".png", "image/png" },
{".jfif", "image/pipeg" },
{".jpz", "image/jpeg" },
{".htm", "text/html" },
{".html", "text/html" },
{".xml","text/plain"},
{".xml","application/xml"},
{".js", "application/x-javascript" },
{".css", "text/css" },
{".dll", "application/x-msdownload" },
{".jar", "application/java-archive" },
{".java", "text/plain" },
{".log", "text/plain" },
{".txt", "text/plain" },
{".wps", "application/vnd.ms-works" },
{".doc", "application/msword" },
{".docx","application/vnd.openxmlformats-officedocument.wordprocessingml.document"},
{".ppt", "application/vnd.ms-powerpoint" },
{".pptx","application/vnd.openxmlformats-officedocument.presentationml.presentation"},
{".pdf", "application/pdf" },
{".exe", "application/octet-stream" },
{".movie", "video/x-sgi-movie" },
{".wav", "audio/x-wav" },
{".wax", "audio/x-ms-wax" },
{".mp2", "video/mpeg" },
{".mp3", "audio/mpeg" },
{".mp4", "video/mp4" },
{".mpe", "video/mpeg" },
{".mpeg", "video/mpeg" },
{".mpg", "video/mpeg" },
{".mpg4", "video/mp4" },
{".zip", "application/zip" },
{".tar", "application/x-tar" },
{".taz", "application/x-tar" },
{".rpm", "audio/x-pn-realaudio-plugin" }
//不太常用的类型
{".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" },
{".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" },
{".awb", "audio/amr-wb" },
{".axs", "application/olescript" },
{".bas", "text/plain" },
{".bcpio", "application/x-bcpio" },
{".bld", "application/bld" },
{".bld2", "application/bld2" },
{".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" },
{".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" },
{".dmg", "application/octet-stream" },
{".dms", "application/octet-stream" },
{".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" },
{".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" },
{".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" },
{ ".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" },
{".jnlp", "application/x-java-jnlp-file" },
{".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" },
{".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" },
{".mpa", "video/mpeg" },
{".mpc", "application/vnd.mpohun.certificate" },
{".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" },
{".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" },
{".pnm", "image/x-portable-anymap" },
{".pnz", "image/png" },
{".pot,", "application/vnd.ms-powerpoint" },
{".ppm", "image/x-portable-pixmap" },
{".pps", "application/vnd.ms-powerpoint" },
{".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" },
{".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" },
{".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" },
{".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" },
{".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" },
{".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" },
{".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" }
参考博文：https://blog.csdn.net/MengDiL_yl/article/details/91047667