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;
}