Yii源码阅读笔记（十）

控制器类，所有控制器的基类，用于调用模型和布局，输出到视图

 namespace yii\base;

 use Yii;

 /**
  * Controller is the base class for classes containing controller logic.
  * 控制器，是所用控制器类的基类
  *
  * @property Module[] $modules  只读属性  当前控制器的所有模块
  *
  * @property string $route  (module ID, controller ID and action ID)  当前请求的路径  只读属性 可以获取到请求的路径
  *
  * @property string $uniqueId  以module ID（如果有的话） 为前缀的controller ID  应该是唯一标识的作用
  *
  * @property View|\yii\web\View $view 视图 object 用来传递视图或视图文件.
  *
  * @property string $viewPath 包含当前控制器的视图目录.
  *
  * @author Qiang Xue <qiang.xue@gmail.com>
  * @since 2.0
  */
 class Controller extends Component implements ViewContextInterface
 {
     /**
      * @event ActionEvent an event raised right before executing a controller action.
      * You may set [[ActionEvent::isValid]] to be false to cancel the action execution.
      * 在执行beforeAction方法时触发的事件，如果对事件的isValid属性设置为false，将取消action的执行
      */
     const EVENT_BEFORE_ACTION = 'beforeAction';
     /**
      * @event ActionEvent an event raised right after executing a controller action.
      * 在执行afterAction方法是触发的事件
      */
     const EVENT_AFTER_ACTION = 'afterAction';

     /**
      * @var string the ID of this controller.
      * 控制器id，
      */
     public $id;
     /**
      * @var Module $module the module that this controller belongs to.
      * 所属模块
      */
     public $module;
     /**
      * @var string the ID of the action that is used when the action ID is not specified
      * in the request. Defaults to 'index'.
      * 控制器中默认动作，默认为index
      */
     public $defaultAction = 'index';
     /**
      * @var string|boolean the name of the layout to be applied to this controller's views.
      * This property mainly affects the behavior of [[render()]].
      * Defaults to null, meaning the actual layout value should inherit that from [[module]]'s layout value.
      * If false, no layout will be applied.
      * 布局文件，如果设置为false，则不使用布局文件
      */
     public $layout;
     /**
      * @var Action the action that is currently being executed. This property will be set
      * by [[run()]] when it is called by [[Application]] to run an action.
      * 当前下面执行的action，可在事件中根据这个action来执行不同的操作
      */
     public $action;

     /**
      * @var View the view object that can be used to render views or view files.
      * 视图对象，用来定义输出的视图文件
      */
     private $_view;
     /**
      * @var string the root directory that contains view files for this controller.
      */
     private $_viewPath;

     /**
      * @param string $id 当前控制器的ID
      * @param Module $module 当前控制器的模块
      * @param array $config 初始化对像时的配置文件
      */
     public function __construct($id, $module, $config = [])
     {
         //初始化指定控制器id，模块，根据配置文件初始化控制器对象
         $this->id = $id;
         $this->module = $module;
         parent::__construct($config);
     }

     /**
      * Declares external actions for the controller.
      * 定义action   声明控制器的外部操作
      * This method is meant to be overwritten to declare external actions for the controller.
      * It should return an array, with array keys being action IDs, and array values the corresponding
      * action class names or action configuration arrays. For example,
      * 这个用来指定独立的action，返回格式为name-value的数组，name为action的id,value为action类的实现，如：
      *
      * ```php
      * return [
      *     'action1' => 'app\components\Action1',
      *     'action2' => [
      *         'class' => 'app\components\Action2',
      *         'property1' => 'value1',
      *         'property2' => 'value2',
      *     ],
      * ];
      * ```
      *
      * [[\Yii::createObject()]] will be used later to create the requested action
      * using the configuration provided here.
      * 这个主要是用于在子类中重写
      */

     public function actions()
     {
         return [];
     }

     /**
      * Runs an action within this controller with the specified action ID and parameters.
      * If the action ID is empty, the method will use [[defaultAction]].
      * $id 为action的id,也就是操作的名称，如定义的actionIndex，那么id就为Index。
      * 如果没有定义 action ID，就会调用默认的操作，例如常用的index
      *
      * @param string $id 操作id，也就是操作名
      * @param array $params the parameters (name-value pairs) to be passed to the action.
      * @return mixed the result of the action.
      * @throws InvalidRouteException if the requested action ID cannot be resolved into an action successfully.
      * @see createAction()
      */
     public function runAction($id, $params = [])
     {
         //创建action
         $action = $this->createAction($id);
         if ($action === null) {
             //创建action失败，抛出异常
             throw new InvalidRouteException('Unable to resolve the request: ' . $this->getUniqueId() . '/' . $id);
         }
         //写入trace信息
         Yii::trace('Route to run: ' . $action->getUniqueId(), __METHOD__);

         if (Yii::$app->requestedAction === null) {
             Yii::$app->requestedAction = $action;//不知道这个是干嘛用的0.0
         }

         $oldAction = $this->action;//将action中的信息保存到oldAction
         $this->action = $action; //将当前的action写入action属性中
         //用来保存当前控制器的所有父模块，顺序为由子模块到父模块
         $modules = [];
         $runAction = true;

          /*
          * 获取当前控制器的所有的模块，并执行每个模块的beforeAction来检查当前的action是否可以执行，
          * 注意：getModules返回的数组顺序为：从父模块到子模块，
          * 所以在执行beforeAction的时候，先检查最外层的父模块，然后检查子模块。
          *
          * 然而在执行afterAction的时候，顺序就反过来了，先执行子模块，最后执行父模块。
          *
          */
         foreach ($this->getModules() as $module) {
             if ($module->beforeAction($action)) {
                 array_unshift($modules, $module);
             } else {
                 $runAction = false;
                 break;
             }
         }

         $result = null;
          //如果所有的父模块都满足执行的条件
         if ($runAction && $this->beforeAction($action)) {//判断当前控制器中beforeAction
             // 由生成的action对象来执行runWithParams方法
             $result = $action->runWithParams($params);
                 //执行完后，再执行afterAction方法
             $result = $this->afterAction($action, $result);

              //执行所有父模块的afterAction
             foreach ($modules as $module) {
                 /* @var $module Module */
                 $result = $module->afterAction($action, $result);
             }
         }
         $this->action = $oldAction;//有什么用呢？，看完后面的在回头看吧

         return $result;
     }