action() public method

public action ( )
    }
}
class ProxySubject extends Subject
{
    // 代理主题角色
    private $_real_subject = NULL;
    public function __construct()
    {
    }
    public function action()
    {
        $this->_beforeAction();
        if (is_null($this->_real_subject)) {
            $this->_real_subject = new RealSubject();
        }
        $this->_real_subject->action();
        $this->_afterAction();
    }
    private function _beforeAction()
    {
        echo '在action前,我想干点啥....';
    }
    private function _afterAction()
    {
        echo '在action后,我还想干点啥....';
    }
}
// client
$subject = new ProxySubject();
$subject->action();