android源码学习 yii2源码学习笔记二十）

Widget类是所有部件的基类。yii2\base\Widget.php

  1 php
  2/**
  3 * @link http://www.yiiframework.com/  4 * @copyright Copyright (c) 2008 Yii Software LLC
  5 * @license http://www.yiiframework.com/license/  6*/  7  8namespace yii\base;
  9 10use Yii;
 11use ReflectionClass;
 12 13/**
 14 * Widget is the base class for widgets.
 15 * Widget是所有小部件的基类
 16 * @property string $id ID of the widget. 小部件标识
 17 * @property \yii\web\View $view The view object that can be used to render views or view files. Note that the
 18 * type of this property differs in getter and setter. See [[getView()]] and [[setView()]] for details.
 19 * 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
 20 * @property string $viewPath The directory containing the view files for this widget. This property is
 21 * read-only. 包含此控件的视图文件目录
 22 *
 23 * @author Qiang Xue  24 * @since 2.0
 25*/ 26class Widget extends Component implements ViewContextInterface
 27{
 28/**
 29     * @var integer a counter used to generate [[id]] for widgets.
 30     * @internal 用于生成widget ID的计数器
 31*/ 32publicstatic $counter = 0;
 33/**
 34     * @var string the prefix to the automatically generated widget IDs.
 35     * @see getId() 自动生成的前缀
 36*/ 37publicstatic $autoIdPrefix = 'w';
 38/**
 39     * @var Widget[] the widgets that are currently being rendered (not ended). This property
 40     * is maintained by [[begin()]] and [[end()]] methods. 目前正在渲染的小部件
 41     * @internal
 42*/ 43publicstatic $stack = [];
 44 45 46/**
 47     * Begins a widget.  开始一个部件
 48     * This method creates an instance of the calling class. It will apply the configuration
 49     * to the created instance. A matching [[end()]] call should be called later.
 50     * 将应用配置文件创建调用类的实例，与[end()]方法相对应
 51     * @param array $config name-value pairs that will be used to initialize the object properties
 52     * 用于初始化属性的参数
 53     * @return static the newly created widget instance 静态新创建的部件实例
 54*/ 55publicstatic function begin($config = [])
 56    {
 57         $config['class'] = get_called_class();//后期静态绑定类的名称 58/* @var $widget Widget */ 59         $widget = Yii::createObject($config);//通过类名和传入的配置，实例化调用类 60static::$stack[] = $widget;//将对象放入正在渲染的部件堆栈中 61 62return $widget;
 63    }
 64 65/**
 66     * Ends a widget.   结束小部件
 67     * Note that the rendering result of the widget is directly echoed out.渲染结果是直接呼应的
 68     * @return static the widget instance that is ended. 静态结束的部件实例。
 69     * @throws InvalidCallException if [[begin()]] and [[end()]] calls are not properly nested
 70*/ 71publicstatic function end()
 72    {
 73if (!empty(static::$stack)) {//正在呈现的小部件堆栈中存在调用类实例 74             $widget = array_pop(static::$stack);//从堆栈中删除最后一个实例 75if (get_class($widget) === get_called_class()) {
 76                 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 77return $widget;
 78             } else {
 79thrownew InvalidCallException("Expecting end() of " . get_class($widget) . ", found " . get_called_class());
 80            }
 81         } else {
 82thrownew InvalidCallException("Unexpected " . get_called_class() . '::end() call. A matching begin() is not found.');
 83        }
 84    }
 85 86/**
 87     * Creates a widget instance and runs it.   创建一个部件实例，并运行
 88     * The widget rendering result is returned by this method. 返回部件渲染的结果。
 89     * @param array $config name-value pairs that will be used to initialize the object properties
 90     * 用于初始化对象属性的参数
 91     * @return string the rendering result of the widget. 控件的渲染结果。
 92*/ 93publicstatic function widget($config = [])
 94    {
 95         ob_start(); //打开输出缓冲区 96         ob_implicit_flush(false);//关闭绝对刷新 97/* @var $widget Widget */ 98         $config['class'] = get_called_class(); //获取调用类的类名 99         $widget = Yii::createObject($config);   //实例化类100         $out = $widget->run();//运行部件101102return ob_get_clean() . $out; //返回内部缓冲区的内容，关闭缓冲区103    }
104105private $_id;
106107/**
108     * Returns the ID of the widget. 返回插件的标识
109     * @param boolean $autoGenerate whether to generate an ID if it is not set previously
110     * 是否生成一个唯一标识，如果没有设置
111     * @return string ID of the widget. 部件唯一标识
112*/113public function getId($autoGenerate = true)
114    {
115if ($autoGenerate && $this->_id === null) {
116//如果标识为空，并且设置为允许自动生成标识，自动生成117             $this->_id = static::$autoIdPrefix . static::$counter++;
118        }
119120return $this->_id;
121    }
122123/**
124     * Sets the ID of the widget. 设置小部件标识
125     * @param string $value id of the widget. 部件的标识。
126*/127public function setId($value)
128    {
129         $this->_id = $value;
130    }
131132private $_view;
133134/**
135     * Returns the view object that can be used to render views or view files.返回视图对象
136     * The [[render()]] and [[renderFile()]] methods will use
137     * this view object to implement the actual view rendering.
138     * [render()]和[renderFile()]方法用视图对象实现实际的视图显示。
139     * If not set, it will default to the "view" application component.
140     * @return \yii\web\View the view object that can be used to render views or view files.
141*/142public function getView()
143    {
144if ($this->_view === null) {
145             $this->_view = Yii::$app->getView();//如果视图对象为空，调用getView()取得视图对象实例146        }
147148return $this->_view;
149    }
150151/**
152     * 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
153     * @param View $view the view object that can be used to render views or view files.
154*/155public function setView($view)
156    {
157         $this->_view = $view;//要用的视图对象158    }
159160/**
161     * Executes the widget. 执行部件
162     * @return string the result of widget execution to be outputted.
163     * 控件执行的结果输出。
164*/165public function run()
166    {
167    }
168169/**
170     * Renders a view.
171     * The view to be rendered can be specified in one of the following formats:
172     * 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
173     * - path alias (e.g. "@app/views/site/index");
174     * - absolute path within application (e.g. "//site/index"): the view name starts with double slashes.
175     *   The actual view file will be looked for under the [[Application::viewPath|view path]] of the application.
176     * - absolute path within module (e.g. "/site/index"): the view name starts with a single slash.
177     *   The actual view file will be looked for under the [[Module::viewPath|view path]] of the currently
178     *   active module.
179     * - relative path (e.g. "index"): the actual view file will be looked for under [[viewPath]].
180     *
181     * If the view name does not contain a file extension, it will use the default one `.php`.
182     *
183     * @param string $view the view name.   视图名
184     * @param array $params the parameters (name-value pairs) that should be made available in the view.
185     * 在视图中可用的参数
186     * @return string the rendering result. 渲染结果
187     * @throws InvalidParamException if the view file does not exist.
188*/189public function render($view, $params = [])
190    {
191//调用view类中的render渲染指定的视图192return $this->getView()->render($view, $params, $this);
193    }
194195/**
196     * Renders a view file. 渲染一个视图文件 同上
197     * @param string $file the view file to be rendered. This can be either a file path or a path alias.
198     * @param array $params the parameters (name-value pairs) that should be made available in the view.
199     * @return string the rendering result.
200     * @throws InvalidParamException if the view file does not exist.
201*/202public function renderFile($file, $params = [])
203    {
204return $this->getView()->renderFile($file, $params, $this);
205    }
206207/**
208     * Returns the directory containing the view files for this widget. 返回视图文件路径
209     * The default implementation returns the 'views' subdirectory under the directory containing the widget class file.
210     * @return string the directory containing the view files for this widget.
211*/212public function getViewPath()
213    {
214         $class = new ReflectionClass($this);
215//取得部件类文件的目录，拼接为视图目录216return dirname($class->getFileName()) . DIRECTORY_SEPARATOR . 'views';
217    }
218 }

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