Yii2源码学习之yii\base\Behavior代码详解

╰半夏微凉° 2022-07-16 13:44 254阅读 0赞

<?php
    /**
     * @link http://www.yiiframework.com/
     * @copyright Copyright (c) 2008 Yii Software LLC
     * @license http://www.yiiframework.com/license/
     */
    
    namespace yii\base;
    
    /**
     * Behavior is the base class for all behavior classes.
     * 所有行为的基类
     *
     * A behavior can be used to enhance the functionality of an existing component without modifying its code.
     * In particular, it can "inject" its own methods and properties into the component
     * and make them directly accessible via the component. It can also respond to the events triggered in the component
     * and thus intercept the normal code execution.
     * 用来增强现有组件的功能而不修改它的代码。它可以添加自己的方法和属性组件
     * 使他们可以直接通过组件访问。还可以响应组件中触发的事件，拦截正常的代码执行。
     *
     * @author Qiang Xue <qiang.xue@gmail.com>
     * @since 2.0
     *
     * 继承父类Object
     */
    class Behavior extends Object
    {
        /**
         * @var Component the owner of this behavior
         * 行为组件的所有者,要附加行为对象的组件。
         */
        public $owner;
    
    
        /**
         * Declares event handlers for the [[owner]]'s events.
         * 声明[[owner]]的事件处理程序
         *
         * Child classes may override this method to declare what PHP callbacks should
         * be attached to the events of the [[owner]] component.
         * 子类可以重写此方法 php回调应连接 [[owner]]组件。
         *
         * The callbacks will be attached to the [[owner]]'s events when the behavior is
         * attached to the owner; and they will be detached from the events when
         * the behavior is detached from the component.
         * 当行为被连接到owner时回调将附在[[owner]]的事件中，当行为从组件中分离时，它们将被分离
         *
         * The callbacks can be any of the following:
         *
         * - method in this behavior: `'handleClick'`, equivalent to `[$this, 'handleClick']`
         * - object method: `[$object, 'handleClick']`
         * - static method: `['Page', 'handleClick']`
         * - anonymous function: `function ($event) { ... }`
         *
         * The following is an example:
         * 下面是一个例子
         *
         * ```php
         * [
         *     Model::EVENT_BEFORE_VALIDATE => 'myBeforeValidate',
         *     Model::EVENT_AFTER_VALIDATE => 'myAfterValidate',
         * ]
         * ```
         *
         * @return array events (array keys) and the corresponding event handler methods (array values).
         * 事件和相应的事件处理方法
         */
        public function events()
        {
            // Behavior 基类本身没用，主要是子类使用，重载这个函数返回一个数组表
            // 示行为所关联的事件
            //用于表示行为所有要响应的事件
            return [];
        }
    
        /**
         * Attaches the behavior object to the component. 绑定行为到组件
         * The default implementation will set the [[owner]] property
         * and attach event handlers as declared in [[events]].
         * 默认设置[[owner]]属性并将事件处理程序绑定到组件
         * Make sure you call the parent implementation if you override this method. 如果重写方法，确保调用父类去实现
         * @param Component $owner the component that this behavior is to be attached to. 行为绑定到$owner组件
         */
        public function attach($owner)
        {
            $this->owner = $owner;//设置 $owner ，使得所依附的对象可以访问、操作
            foreach ($this->events() as $event => $handler) {
                //将准备响应的事件，通过所依附类的 on()方法 绑定到类上
                $owner->on($event, is_string($handler) ? [$this, $handler] : $handler);
            }
        }
    
        /**
         * Detaches the behavior object from the component. 解除绑定的行为
         * The default implementation will unset the [[owner]] property  默认取消 owner的属性
         * and detach event handlers declared in [[events]]. 将events中的事件程序解除绑定
         * Make sure you call the parent implementation if you override this method. 如果重写方法，确保调用父类去实现
         */
        public function detach()
        {
            if ($this->owner) {
                foreach ($this->events() as $event => $handler) {
       //遍历行为中 events() 返回的数组
                    //通过Component的 off() 将绑定到类上的事件解除
                    $this->owner->off($event, is_string($handler) ? [$this, $handler] : $handler);
                }
                $this->owner = null;//将 $owner 设置为 null ，表示这个解除绑定
            }
        }
    }
    
    
    /*
     * 一个绑定了行为的类，表现起来是这样的:
     *
     */
    
    // Step 1: 定义一个将绑定行为的类
    // class MyClass extends yii\base\Component
    //  {
        
        // 空的
    // }
    
    // Step 2: 定义一个行为类，他将绑定到MyClass上
    // class MyBehavior extends yii\base\Behavior
    //{
        
        // 行为的一个属性
    //    public $property1 = 'This is property in MyBehavior.';
    
        // 行为的一个方法
    //    public function method1()
    //    {
        
    //        return 'Method in MyBehavior is called.';
    //    }
    // }
    
    //$myClass = new MyClass();
    //$myBehavior = new MyBehavior();
    
    // Step 3: 将行为绑定到类上
    //$myClass->attachBehavior('myBehavior', $myBehavior);
    
    // Step 4: 访问行为中的属性和方法，就和访问类自身的属性和方法一样
    //echo $myClass->property1;
    //echo $myClass->method1();