yii2 controller behavior函数的beforeAction实现原理

首先写一个例子，在siteController中覆盖behaviors函数

    public function behaviors()
    {
        return [
            "access" => [
                "class"=>AuthFilter::className(),
                "only"=>["index"],
              ],
            "access11" => [
                "class"=>AuthFilter::className(),
                "only"=>["index"],
            ],
        ];
    }

AuthFilter的定义

class AuthFilter extends ActionFilter
{
    public function beforeAction($action)
    {
        echo "this is echo when before Action";
        return parent::beforeAction($action); // TODO: Change the autogenerated stub
    }

    public function afterAction($action, $result)
    {
        echo "this is echo when after action";
        return parent::afterAction($action, $result); // TODO: Change the autogenerated stub
    }
}

我们知道controller的拦截器是在behavior中进行定义的，而controller的拦截器的函数必须定义beforeAction  和afterAction，这是为什么呢，因为这是当前Controller的祖父类定义的！！！

我的SiteController的父类是web的Controller，该类的父类是yiiasecontroller，每次 一个请求的到来，都会执行祖父类Controller的runAction

 public function runAction($id, $params = [])
    {
        $action = $this->createAction($id);
        if ($action === null) {
            throw new InvalidRouteException("Unable to resolve the request: " . $this->getUniqueId() . "/" . $id);
        }

        Yii::trace("Route to run: " . $action->getUniqueId(), __METHOD__);

        if (Yii::$app->requestedAction === null) {
            Yii::$app->requestedAction = $action;
        }

        $oldAction = $this->action;
        $this->action = $action;

        $modules = [];
        $runAction = true;

        // call beforeAction on modules
        foreach ($this->getModules() as $module) {
            if ($module->beforeAction($action)) {    //这里执行了一次，调用点是yiiwebapplication
                array_unshift($modules, $module);
            } else {
                $runAction = false;
                break;
            }
        }

        $result = null;

        if ($runAction && $this->beforeAction($action)) {  //可以看到，执行beforeAction之后，并且返回true，之后参会进行下一步操作
            // run the action
            $result = $action->runWithParams($params);

            $result = $this->afterAction($action, $result);

            // call afterAction on modules
            foreach ($modules as $module) {
                /* @var $module Module */
                $result = $module->afterAction($action, $result);
            }
        }

        $this->action = $oldAction;

        return $result;
    }

祖父类执行了beforeAction，但是大家需要注意的是beforeAction执行了两次，一次是webapplication执行beforeAction，这样是不会执行我们controller中的behavior中的beforeAction函数的，而当执行$this->beforeAction的时候其定义如下：

    public function beforeAction($action)
    {
        $event = new ActionEvent($action);
        $this->trigger(self::EVENT_BEFORE_ACTION, $event);
        return $event->isValid;
    }

这样就触发了trigger函数，其函数定义如下：

  public function trigger($name, Event $event = null)
    {
        $this->ensureBehaviors();
        if (!empty($this->_events[$name])) {
            if ($event === null) {
                $event = new Event;
            }
            if ($event->sender === null) {
                $event->sender = $this;
            }
            $event->handled = false;
            $event->name = $name;

            foreach ($this->_events[$name] as $handler) {
                $event->data = $handler[1];
                call_user_func($handler[0], $event);//此处进行beforeAction的调用
                // stop further handling if the event is handled
                if ($event->handled) {
                    return;
                }
            }
        }
        // invoke class-level attached handlers
        Event::trigger($this, $name, $event);
    }

因为我们在$this 也就是siteController中定义了behaviors函数，在ensureBahaviors中就将behavior放在了component中的_behaviors数组当中，同时将对应的数据写在了_events当中，其$name 也是beforeAction,这样就会执行call_user_func函数，调用我们的接口

只是此时$name 是beforeAction，而 $handler是一个数组，第一个元素是定义类的对象，第二个是要执行的函数名称"beforeFilter"，该函数的定义是在ActionFilter类中定义的

    /**
     * @param ActionEvent $event
     */
    public function beforeFilter($event)
    {
        if (!$this->isActive($event->action)) {
            return;
        }

        $event->isValid = $this->beforeAction($event->action);
        if ($event->isValid) {
            // call afterFilter only if beforeFilter succeeds
            // beforeFilter and afterFilter should be properly nested
            $this->owner->on(Controller::EVENT_AFTER_ACTION, [$this, "afterFilter"], null, false);
        } else {
            $event->handled = true;
        }
    }

由该函数转调子类的beforeAction，这样就完成了我们的整个操作，需要注意的是如果有多个behavior的时候，则会根据behaviors数组的顺序，依次进行调用！！！