PHPePub\Core\EPub::setLanguage PHP Method

    function setLanguage($language)
    {
        if ($this->isFinalized || mb_strlen($language) != 2) {
            return false;
        }
        $this->language = $language;
        return true;
    }

 /**
  * @inheritdoc
  */
 public function initialization(Config $config)
 {
     $this->epub = new EPub();
     $this->epub->setTitle($config->get('title', 'untitled'));
     if ($isbn = $config->get('ISBN')) {
         $this->epub->setIdentifier($isbn, EPub::IDENTIFIER_ISBN);
     } else {
         $this->epub->setIdentifier($config->get('uri'), EPub::IDENTIFIER_URI);
     }
     $this->epub->setLanguage($config->get('language', 'zh-cn'));
     // Not needed, but included for the example, Language is mandatory, but EPub defaults to "en". Use RFC3066 Language codes, such as "en", "da", "fr" etc.
     $this->epub->setDescription($config->get('description'));
     $this->epub->setAuthor($config->get('author'), $config->get('author'));
     $this->epub->setPublisher($config->get('publisher.name'), $config->get('publisher.url'));
     // I hope this is a non existent address :)
     $this->epub->setDate(time());
     // Strictly not needed as the book date defaults to time().
     $this->epub->setRights($config->get('copyright'));
     // As this is generated, this _could_ contain the name or licence information of the user who purchased the book, if needed. If this is used that way, the identifier must also be made unique for the book.
     $this->epub->setSourceURL($config->get('publisher.url'));
     $this->epub->addDublinCoreMetadata(DublinCore::CONTRIBUTOR, "PHP");
     $this->epub->buildTOC(NULL, "toc", "目录", TRUE, TRUE);
 }