Widget类

Widget类是所有部件的基类。yii2\base\Widget.php

<?php/** * @link http://www.yiiframework.com/ * @copyright Copyright (c) 2008 Yii Software LLC * @license http://www.yiiframework.com/license/ */namespace yii\base;use Yii;use ReflectionClass;/** * Widget is the base class for widgets. * Widget是所有小部件的基类 * @property string $id ID of the widget. 小部件标识 * @property \yii\web\View $view The view object that can be used to render views or view files. Note that the * type of this property differs in getter and setter. See [[getView()]] and [[setView()]] for details. * 用于渲染视图或视图文件的视图对象 在getter 和 setter中是不同的 * @property string $viewPath The directory containing the view files for this widget. This property is * read-only. 包含此控件的视图文件目录 * * @author Qiang Xue <[e-mail]> * @since 2.0 */class Widget extends Component implements ViewContextInterface{    /**     * @var integer a counter used to generate [[id]] for widgets.     * @internal 用于生成widget ID的计数器     */    public static $counter = 0;    /**     * @var string the prefix to the automatically generated widget IDs.     * @see getId() 自动生成的前缀     */    public static $autoIdPrefix = 'w';    /**     * @var Widget[] the widgets that are currently being rendered (not ended). This property     * is maintained by [[begin()]] and [[end()]] methods. 目前正在渲染的小部件     * @internal     */    public static $stack = [];    /**     * Begins a widget.  开始一个部件     * This method creates an instance of the calling class. It will apply the configuration     * to the created instance. A matching [[end()]] call should be called later.     * 将应用配置文件创建调用类的实例，与[end()]方法相对应     * @param array $config name-value pairs that will be used to initialize the object properties     * 用于初始化属性的参数     * @return static the newly created widget instance 静态新创建的部件实例     */    public static function begin($config = [])    {        $config['class'] = get_called_class();//后期静态绑定类的名称        /* @var $widget Widget */        $widget = Yii::createObject($config);//通过类名和传入的配置，实例化调用类        static::$stack[] = $widget;//将对象放入正在渲染的部件堆栈中        return $widget;    }    /**     * Ends a widget.   结束小部件     * Note that the rendering result of the widget is directly echoed out.渲染结果是直接呼应的     * @return static the widget instance that is ended. 静态结束的部件实例。     * @throws InvalidCallException if [[begin()]] and [[end()]] calls are not properly nested     */    public static function end()    {        if (!empty(static::$stack)) {//正在呈现的小部件堆栈中存在调用类实例            $widget = array_pop(static::$stack);//从堆栈中删除最后一个实例            if (get_class($widget) === get_called_class()) {                echo $widget->run(); //如果删除的实例类名和当前调用类名相同，输出小部件的内容                return $widget;            } else {                throw new InvalidCallException("Expecting end() of " . get_class($widget) . ", found " . get_called_class());            }        } else {            throw new InvalidCallException("Unexpected " . get_called_class() . '::end() call. A matching begin() is not found.');        }    }    /**     * Creates a widget instance and runs it.   创建一个部件实例，并运行     * The widget rendering result is returned by this method. 返回部件渲染的结果。     * @param array $config name-value pairs that will be used to initialize the object properties     * 用于初始化对象属性的参数     * @return string the rendering result of the widget. 控件的渲染结果。     */    public static function widget($config = [])    {        ob_start(); //打开输出缓冲区        ob_implicit_flush(false);//关闭绝对刷新        /* @var $widget Widget */        $config['class'] = get_called_class(); //获取调用类的类名        $widget = Yii::createObject($config);   //实例化类        $out = $widget->run();//运行部件        return ob_get_clean() . $out; //返回内部缓冲区的内容，关闭缓冲区    }    private $_id;    /**     * Returns the ID of the widget. 返回插件的标识     * @param boolean $autoGenerate whether to generate an ID if it is not set previously     * 是否生成一个唯一标识，如果没有设置     * @return string ID of the widget. 部件唯一标识     */    public function getId($autoGenerate = true)    {        if ($autoGenerate && $this->_id === null) {            //如果标识为空，并且设置为允许自动生成标识，自动生成            $this->_id = static::$autoIdPrefix . static::$counter++;        }        return $this->_id;    }    /**     * Sets the ID of the widget. 设置小部件标识     * @param string $value id of the widget. 部件的标识。     */    public function setId($value)    {        $this->_id = $value;    }    private $_view;    /**     * Returns the view object that can be used to render views or view files.返回视图对象     * The [[render()]] and [[renderFile()]] methods will use     * this view object to implement the actual view rendering.     * [render()]和[renderFile()]方法用视图对象实现实际的视图显示。     * If not set, it will default to the "view" application component.     * @return \yii\web\View the view object that can be used to render views or view files.     */    public function getView()    {        if ($this->_view === null) {            $this->_view = Yii::$app->getView();//如果视图对象为空，调用getView()取得视图对象实例        }        return $this->_view;    }    /**     * Sets the view object to be used by this widget. 设置当前部件调用的视图对象实例     * @param View $view the view object that can be used to render views or view files.     */    public function setView($view)    {        $this->_view = $view;//要用的视图对象    }    /**     * Executes the widget. 执行部件     * @return string the result of widget execution to be outputted.     * 控件执行的结果输出。     */    public function run()    {    }    /**     * Renders a view.     * The view to be rendered can be specified in one of the following formats:     * 渲染一个视图   实际调用View类中的同名方法 渲染的视图可以用下列方式指定路径     * - path alias (e.g. "@app/views/site/index");     * - absolute path within application (e.g. "//site/index"): the view name starts with double slashes.     *   The actual view file will be looked for under the [[Application::viewPath|view path]] of the application.     * - absolute path within module (e.g. "/site/index"): the view name starts with a single slash.     *   The actual view file will be looked for under the [[Module::viewPath|view path]] of the currently     *   active module.     * - relative path (e.g. "index"): the actual view file will be looked for under [[viewPath]].     *     * If the view name does not contain a file extension, it will use the default one `.php`.     *     * @param string $view the view name.   视图名     * @param array $params the parameters (name-value pairs) that should be made available in the view.     * 在视图中可用的参数     * @return string the rendering result. 渲染结果     * @throws InvalidParamException if the view file does not exist.     */    public function render($view, $params = [])    {        //调用view类中的render渲染指定的视图        return $this->getView()->render($view, $params, $this);    }    /**     * Renders a view file. 渲染一个视图文件 同上     * @param string $file the view file to be rendered. This can be either a file path or a path alias.     * @param array $params the parameters (name-value pairs) that should be made available in the view.     * @return string the rendering result.     * @throws InvalidParamException if the view file does not exist.     */    public function renderFile($file, $params = [])    {        return $this->getView()->renderFile($file, $params, $this);    }    /**     * Returns the directory containing the view files for this widget. 返回视图文件路径     * The default implementation returns the 'views' subdirectory under the directory containing the widget class file.     * @return string the directory containing the view files for this widget.     */    public function getViewPath()    {        $class = new ReflectionClass($this);        //取得部件类文件的目录，拼接为视图目录        return dirname($class->getFileName()) . DIRECTORY_SEPARATOR . 'views';    }}