Yii2.0遵循默认规则指定控制器ID映射到同名控制器类([路径正确],如site对应app\controller\SiteController)。通过配置yii\base\Application::controllerMap属性,改变这个默认规则,如例:
[ 'controllerMap' => [ [ 'admin' => 'app\controllers\UserController', 'site' => [ 'class' => 'app\controllers\PostController', 'enableCsrfValidation' => false, ], ], ], ]