十八大学习笔记 yii2源码学习笔记（十八）
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2022-04-24 15:28:30
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View继承了component，用于渲染视图文件：yii2\base\View.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 yii\helpers\FileHelper; 12use yii\widgets\Block; 13use yii\widgets\ContentDecorator; 14use yii\widgets\FragmentCache; 15 16/** 17 * View represents a view object in the MVC pattern. 18 * MVC中的视图 19 * View provides a set of methods (e.g. [[render()]]) for rendering purpose. 20 * 视图提供了一套渲染页面的方法 21 * @property string|boolean $viewFile The view file currently being rendered. False if no view file is being 22 * rendered. This property is read-only. 23 * 24 * @author Qiang Xue25 * @since 2.0 26*/ 27class View extends Component 28{ 29/** 30 * @event Event an event that is triggered by [[beginPage()]]. 31 * 事件被[beginPage()]触发 32*/ 33const EVENT_BEGIN_PAGE = 'beginPage'; 34/** 35 * @event Event an event that is triggered by [[endPage()]]. 36 * 事件被[endPage()]触发 37*/ 38const EVENT_END_PAGE = 'endPage'; 39/** 40 * @event ViewEvent an event that is triggered by [[renderFile()]] right before it renders a view file. 41 * 事件被[renderFile()]触发前呈现一个视图文件 42*/ 43const EVENT_BEFORE_RENDER = 'beforeRender'; 44/** 45 * @event ViewEvent an event that is triggered by [[renderFile()]] right after it renders a view file. 46 * 事件被[renderFile()]触发后呈现一个视图文件 47*/ 48const EVENT_AFTER_RENDER = 'afterRender'; 49 50/** 51 * @var ViewContextInterface the context under which the [[renderFile()]] method is being invoked. 52 * ViewContextInterface背景下 [renderFile()]方法被调用 53*/ 54public $context; 55/** 56 * @var mixed custom parameters that are shared among view templates. 57 * 视图模板*享的自定义参数 58*/ 59public $params = []; 60/** 61 * @var array a list of available renderers indexed by their corresponding supported file extensions. 62 * Each renderer may be a view renderer object or the configuration for creating the renderer object. 63 * 一个可用的渲染索引列表。每个渲染器是一个渲染器对象或创建渲染对象配置数组 64 * For example, the following configuration enables both Smarty and Twig view renderers: 65 * 66 * ~~~ 67 * [ 68 * 'tpl' => ['class' => 'yii\smarty\ViewRenderer'], 69 * 'twig' => ['class' => 'yii\twig\ViewRenderer'], 70 * ] 71 * ~~~ 72 * 73 * If no renderer is available for the given view file, the view file will be treated as a normal PHP 74 * and rendered via [[renderPhpFile()]]. 75*/ 76public $renderers; 77/** 78 * @var string the default view file extension. This will be appended to view file names if they don't have file extensions. 79 * 默认视图文件扩展名，文件没有扩展名的情况下自动加载 80*/ 81public $defaultExtension = 'php'; 82/** 83 * @var Theme|array|string the theme object or the configuration for creating the theme object. 84 * If not set, it means theming is not enabled.主题对象或创建主题对象的配置 未设置则不启用 85*/ 86public $theme; 87/** 88 * @var array a list of named output blocks. The keys are the block names and the values 89 * are the corresponding block content. You can call [[beginBlock()]] and [[endBlock()]] 90 * to capture small fragments of a view. They can be later accessed somewhere else 91 * through this property. 92 * 一个输出块列表。键是块名称值为内容。可以调用 [beginblock()]和[endblock()]捕获视图的小片段 93 * 可以在其他地方通过这个属性访问。 94*/ 95public $blocks; 96/** 97 * @var array a list of currently active fragment cache widgets. This property 98 * is used internally to implement the content caching feature. Do not modify it directly. 99 * 当前操作片段的缓存部件列表。用于内部实现内容缓存功能。不要直接修改 100 * @internal 101*/102public $cacheStack = []; 103/** 104 * @var array a list of placeholders for embedding dynamic contents. This property 105 * is used internally to implement the content caching feature. Do not modify it directly. 106 * 嵌入动态内容占位符列表。 用于内部实现内容缓存功能。不要直接修改 107 * @internal 108*/109public $dynamicPlaceholders = []; 110111/** 112 * @var array the view files currently being rendered. There may be multiple view files being 113 * rendered at a moment because one view may be rendered within another. 114 * 正在渲染的视图文件。可能有多个视图文件被渲染，因为一个视图可以在另一个视图中呈现 115*/116private $_viewFiles = []; 117118119/** 120 * Initializes the view component.初始化视图组件 121*/122public function init() 123 { 124 parent::init(); //调用父类的方法125if (is_array($this->theme)) { 126if (!isset($this->theme['class'])) { 127 $this->theme['class'] = 'yii\base\Theme';//是数组，没有设置类名，则类名'yii\base\Theme'128 } 129 $this->theme = Yii::createObject($this->theme);//设置了类名，调用配置创建对象130 } elseif (is_string($this->theme)) {//以字符串参数的形式创建对象131 $this->theme = Yii::createObject($this->theme); 132 } 133 } 134135/** 136 * Renders a view. 137 * 渲染一个视图 138 * The view to be rendered can be specified in one of the following formats: 139 * 140 * - path alias (e.g. "@app/views/site/index"); 141 * 路径别名 142 * - absolute path within application (e.g. "//site/index"): the view name starts with double slashes. 143 * The actual view file will be looked for under the [[Application::viewPath|view path]] of the application. 144 * 绝对路径，会在[Application::viewPath|view path]下查找文件 145 * - absolute path within current module (e.g. "/site/index"): the view name starts with a single slash. 146 * The actual view file will be looked for under the [[Module::viewPath|view path]] of the [[Controller::module|current module]]. 147 * 模块下的绝对路径，会在[Module::viewPath|view path]下查找文件 148 * - relative view (e.g. "index"): the view name does not start with `@` or `/`. The corresponding view file will be 149 * looked for under the [[ViewContextInterface::getViewPath()|view path]] of the view `$context`. 150 * 相对路径，会在[ViewContextInterface::getViewPath()|view path]下查找文件 151 * If `$context` is not given, it will be looked for under the directory containing the view currently 152 * being rendered (i.e., this happens when rendering a view within another view). 153 * 154 * @param string $view the view name. 视图名称 155 * @param array $params the parameters (name-value pairs) that will be extracted and made available in the view file. 156 * 视图中应用参数 157 * @param object $context the context to be assigned to the view and can later be accessed via [[context]] 158 * in the view. If the context implements [[ViewContextInterface]], it may also be used to locate 159 * the view file corresponding to a relative view name. 对应情景 160 * @return string the rendering result 161 * @throws InvalidParamException if the view cannot be resolved or the view file does not exist. 162 * @see renderFile() 163*/164public function render($view, $params = [], $context = null) 165 { 166 $viewFile = $this->findViewFile($view, $context);//查找视图文件路径167return $this->renderFile($viewFile, $params, $context);//渲染视图文件168 } 169170/** 171 * Finds the view file based on the given view name.通过视图文件名查找视图文件 172 * @param string $view the view name or the path alias of the view file. Please refer to [[render()]] 173 * on how to specify this parameter. 视图名称或路径视图文件的别名 174 * @param object $context the context to be assigned to the view and can later be accessed via [[context]] 175 * in the view. If the context implements [[ViewContextInterface]], it may also be used to locate 176 * the view file corresponding to a relative view name. 对应情景 177 * @return string the view file path. Note that the file may not exist. 文件路径 178 * @throws InvalidCallException if a relative view name is given while there is no active context to 179 * determine the corresponding view file. 180*/181protected function findViewFile($view, $context = null) 182 { 183if (strncmp($view, '@', 1) === 0) { 184// e.g. "@app/views/main" 判断是否是别名路径，是则获取真实路径185 $file = Yii::getAlias($view); 186 } elseif (strncmp($view, '//', 2) === 0) { 187// e.g. "//layouts/main" 以//开始，查找文件路径，拼接视图文件路径188 $file = Yii::$app->getViewPath() . DIRECTORY_SEPARATOR . ltrim($view, '/'); 189 } elseif (strncmp($view, '/', 1) === 0) { 190// e.g. "/site/index"191if (Yii::$app->controller !== null) { 192//以/开始，且控制器存在，查找控制器对应的文件目录，拼接路径193 $file = Yii::$app->controller->module->getViewPath() . DIRECTORY_SEPARATOR . ltrim($view, '/'); 194 } else { 195thrownew InvalidCallException("Unable to locate view file for view '$view': no active controller."); 196 } 197 } elseif ($context instanceof ViewContextInterface) { 198//对应情景存在 查找文件路径，拼接视图文件路径199 $file = $context->getViewPath() . DIRECTORY_SEPARATOR . $view; 200 } elseif (($currentViewFile = $this->getViewFile()) !== false) { 201//当前渲染文件存在，拼接路径202 $file = dirname($currentViewFile) . DIRECTORY_SEPARATOR . $view; 203 } else { 204thrownew InvalidCallException("Unable to resolve view file for view '$view': no active view context."); 205 } 206207if (pathinfo($file, PATHINFO_EXTENSION) !== '') { 208return $file;//视图文件的扩展名不为空，返回扩展名209 } 210 $path = $file . '.' . $this->defaultExtension; //给视图文件添加扩展名211if ($this->defaultExtension !== 'php' && !is_file($path)) { 212 $path = $file . '.php'; 213 } 214215return $path;//返回路径216 } 217218/** 219 * Renders a view file. 220 * 渲染一个视图文件。 221 * If [[theme]] is enabled (not null), it will try to render the themed version of the view file as long 222 * as it is available. 223 * 如果[theme]可用，将渲染视图文件的主题版本直到[theme]不可用 224 * The method will call [[FileHelper::localize()]] to localize the view file. 225 * 调用[FileHelper::localize()]方法本地化视图文件 226 * If [[renderers|renderer]] is enabled (not null), the method will use it to render the view file. 227 * Otherwise, it will simply include the view file as a normal PHP file, capture its output and 228 * return it as a string. 229 * 如果[[renderers|renderer]]启用，该方法将用它来渲染视图文件。否则，将视图文件作为一个正常的PHP文件包含进来，获取其输出并返回一个字符串。 230 * @param string $viewFile the view file. This can be either an absolute file path or an alias of it. 231 * 视图文件。可以是绝对路径或它的别名。 232 * @param array $params the parameters (name-value pairs) that will be extracted and made available in the view file. 233 * 视图文件执行的参数 234 * @param object $context the context that the view should use for rendering the view. If null, 235 * existing [[context]] will be used. 236 * 用于渲染视图的上下文 237 * @return string the rendering result 238 * @throws InvalidParamException if the view file does not exist 239*/240public function renderFile($viewFile, $params = [], $context = null) 241 { 242 $viewFile = Yii::getAlias($viewFile);//处理输入的视图文件名243244if ($this->theme !== null) { 245 $viewFile = $this->theme->applyTo($viewFile);//如果theme非空，应用到视图文件246 } 247if (is_file($viewFile)) { 248 $viewFile = FileHelper::localize($viewFile);//本地化视图文件249 } else { 250thrownew InvalidParamException("The view file does not exist: $viewFile"); 251 } 252253 $oldContext = $this->context; 254if ($context !== null) { 255 $this->context = $context; 256 } 257 $output = ''; 258 $this->_viewFiles[] = $viewFile;//记录当前渲染文件259260if ($this->beforeRender($viewFile, $params)) {//如果前置事件执行成功261 Yii::trace("Rendering view file: $viewFile", __METHOD__);//记录trace信息262 $ext = pathinfo($viewFile, PATHINFO_EXTENSION);//视图文件扩展名263if (isset($this->renderers[$ext])) {//视图文件的扩展名是否支持264if (is_array($this->renderers[$ext]) || is_string($this->renderers[$ext])) { 265 $this->renderers[$ext] = Yii::createObject($this->renderers[$ext]); 266 } 267/* @var $renderer ViewRenderer */268 $renderer = $this->renderers[$ext];//赋值view渲染器对象269 $output = $renderer->render($this, $viewFile, $params);//渲染视图文件270 } else {//视图文件不是支持的类型，以普通php文件处理271 $output = $this->renderPhpFile($viewFile, $params); 272 } 273 $this->afterRender($viewFile, $params, $output); 274 } 275276 array_pop($this->_viewFiles); 277 $this->context = $oldContext; 278279return $output; 280 }
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