直接再实例化D(); 或者M();都会报错。

——————————
无法加载数据库驱动: Think\Db\Driver\
错误位置
FILE: D:\phpStudy\WWW\BookDataCenter\ThinkPHP\Library\Think\Db.class.php 　LINE: 42
TRACE
#0 D:\phpStudy\WWW\BookDataCenter\ThinkPHP\Library\Think\Db.class.php(42): E('???????????????...')
#1 D:\phpStudy\WWW\BookDataCenter\ThinkPHP\Library\Think\Model.class.php(1423): Think\Db::getInstance('')
#2 D:\phpStudy\WWW\BookDataCenter\ThinkPHP\Library\Think\Model.class.php(97): Think\Model->db(0, '', true)
#3 D:\phpStudy\WWW\BookDataCenter\ThinkPHP\Common\functions.php(621): Think\Model->__construct('', '', '')
#4 D:\phpStudy\WWW\BookDataCenter\Application\Book\Controller\BookMainController.class.php(429): M()
#5 [internal function]: Book\Controller\BookMainController->addBook()
#6 D:\phpStudy\WWW\BookDataCenter\ThinkPHP\Library\Think\App.class.php(164): ReflectionMethod->invoke(object(Book\Controller\BookMainController))
#7 D:\phpStudy\WWW\BookDataCenter\ThinkPHP\Library\Think\App.class.php(202): Think\App::exec()
#8 D:\phpStudy\WWW\BookDataCenter\ThinkPHP\Library\Think\Think.class.php(120): Think\App::run()
#9 D:\phpStudy\WWW\BookDataCenter\ThinkPHP\ThinkPHP.php(97): Think\Think::start()
#10 D:\phpStudy\WWW\BookDataCenter\index.php(26): require('D:\phpStudy\WWW...')
#11 {main}