用dokuwiki写了篇文档，想要导出到pdf，于是装了dw2pdf，可是导出之后发现中文都是乱码。
搜索之后，只找到一篇关于问题的博文:http://xwz.me/blog/2011/03/15/dokuwiki_exportpdf/，可惜已经过时了，给的链接也不能用。
最后在官方文档中找到了答案，看来还是文档最全面。
在文档中搜索cjk,可以找到一些条目。
主要看两篇文档，第一个看到的是use_CJK_only

Note: DEPRACATED mPDF >= 5.0 See useAdobeCJK
$mpdf->use_CJK_only = true;
Use this if you are using a CJK codepage with only CJK/ASCII or embedded characters -this will prevent loading of Unicode fonts - keeping file size to a minimum
Ignored if not using a CJK codepage.
Default = false

根据提示找到了useAdobeCJK

(mPDF >= 5.0)
Description
boolean useAdobeCJK
When TRUE, forces mPDF to use the free Adobe CJK Asian fonts, thus keeping the PDF file size to a minimum. This affects text defines using the CSS lang property, which includes the use of AutoFont. Thus a CSS stylesheet defining lang="ja" will be substituted by the Adobe Japanes font. (This will not prevent the use of other CJK fonts if specified by font-family.)
The precise effect it has on different languages/fonts will be specified in the config_cp.php configuration file.
Note: This value can only be set inside the config.php configuration file. To change the value at runtime, you must use $mpdf = new mPDF('-aCJK'); to set as FALSE or $mpdf = new mPDF('+aCJK'); to set as TRUE
Values
useAdobeCJK = TRUE|FALSE
Values
TRUE: DEFAULT Use the free Adobe CJK Asian fonts
FALSE: Use normal embedded fonts

然后修改mpdf/config.php，大致44行，将useAdobeCJK改为true:

$this->useAdobeCJK = true;		// Uses Adobe CJK fonts for CJK languages

之后导出中文正常！