中文乱码有两个环节会出现
第一，从请求体中获得的数据
从请求体中获得的数据要为其进行编码，默认为ISO-8859-1，所以在使用getParameter()时先调用setCharacterEncoding("utf-8")方法对数据进行编码。。
这仅仅对post有效，对get时，因为在生成URL的时候已经对其编码，所以要使用String的构造方法对其重新编码，new String(str.getBytes("iso-8859-1"),"utf-8");
第二，响应给浏览器的数据
响应时，首先要设置给浏览器的文件MIME类型 setContentType("text/html;charset=utf-8")
其次需要设置响应的字符编码，setCharacterType("utf-8")
这样可以解决乱码问题
常见MIME类型
按照功能排列的MIME_type类型
| 类型/子类型 | 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 | |
| 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-outlook | msg |
| 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-shockwave-flash | swf |
| 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 http://www.dreamdu.com | 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 |