View繼承了component，用於渲染視圖文件：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 8 namespace yii\base; 9 10 use Yii; 11 use yii\helpers\FileHelper; 12 use yii\widgets\Block; 13 use yii\widgets\ContentDecorator; 14 use yii\widgets\FragmentCache; 15 16 /** 17 * View represents a view object in the MVC pattern. 18 * MVC中的視圖 19 * View provides a set of methods (e.g. [[render()]]) for rendering purpose. 20 * 視圖提供了一套渲染頁面的方法 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 Xue <[email protected]> 25 * @since 2.0 26 */ 27 class View extends Component 28 { 29 /** 30 * @event Event an event that is triggered by [[beginPage()]]. 31 * 事件被[beginPage()]觸發 32 */ 33 const EVENT_BEGIN_PAGE = 'beginPage'; 34 /** 35 * @event Event an event that is triggered by [[endPage()]]. 36 * 事件被[endPage()]觸發 37 */ 38 const 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()]觸發前呈現一個視圖文件 42 */ 43 const 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()]觸發後呈現一個視圖文件 47 */ 48 const 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()]方法被調用 53 */ 54 public $context; 55 /** 56 * @var mixed custom parameters that are shared among view templates. 57 * 視圖模板中共享的自定義參數 58 */ 59 public $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 * 一個可用的渲染索引列表。每個渲染器是一個渲染器對象或創建渲染對象配置數組 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 */ 76 public $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 * 默認視圖文件擴展名，文件沒有擴展名的情況下自動加載 80 */ 81 public $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.主題對象或創建主題對象的配置 未設置則不啟用 85 */ 86 public $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 * 一個輸出塊列表。鍵是塊名稱值為內容。可以調用 [beginblock()]和[endblock()]捕獲視圖的小片段 93 * 可以在其他地方通過這個屬性訪問。 94 */ 95 public $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 * 當前操作片段的緩存部件列表。用於內部實現內容緩存功能。不要直接修改 100 * @internal 101 */ 102 public $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 * 嵌入動態內容占位符列表。 用於內部實現內容緩存功能。不要直接修改 107 * @internal 108 */ 109 public $dynamicPlaceholders = []; 110 111 /** 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 * 正在渲染的視圖文件。可能有多個視圖文件被渲染，因為一個視圖可以在另一個視圖中呈現 115 */ 116 private $_viewFiles = []; 117 118 119 /** 120 * Initializes the view component.初始化視圖組件 121 */ 122 public function init() 123 { 124 parent::init(); //調用父類的方法 125 if (is_array($this->theme)) { 126 if (!isset($this->theme['class'])) { 127 $this->theme['class'] = 'yii\base\Theme';//是數組，沒有設置類名，則類名'yii\base\Theme' 128 } 129 $this->theme = Yii::createObject($this->theme);//設置了類名，調用配置創建對象 130 } elseif (is_string($this->theme)) {//以字符串參數的形式創建對象 131 $this->theme = Yii::createObject($this->theme); 132 } 133 } 134 135 /** 136 * Renders a view. 137 * 渲染一個視圖 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 * 路徑別名 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 * 絕對路徑，會在[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 * 模塊下的絕對路徑，會在[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 `$context`. 150 * 相對路徑，會在[ViewContextInterface::getViewPath()|view path]下查找文件 151 * If `$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. 視圖名稱 155 * @param array $params the parameters (name-value pairs) that will be extracted and made available in the view file. 156 * 視圖中應用參數 157 * @param object $context the context to be assigned to the view and can later be accessed via [[context]] 158 * in the view. If the context implements [[ViewContextInterface]], it may also be used to locate 159 * the view file corresponding to a relative view name. 對應情景 160 * @return string the rendering result 161 * @throws InvalidParamException if the view cannot be resolved or the view file does not exist. 162 * @see renderFile() 163 */ 164 public function render($view, $params = [], $context = null) 165 { 166 $viewFile = $this->findViewFile($view, $context);//查找視圖文件路徑 167 return $this->renderFile($viewFile, $params, $context);//渲染視圖文件 168 } 169 170 /** 171 * Finds the view file based on the given view name.通過視圖文件名查找視圖文件 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. 視圖名稱或路徑視圖文件的別名 174 * @param object $context the context to be assigned to the view and can later be accessed via [[context]] 175 * in the view. If the context implements [[ViewContextInterface]], it may also be used to locate 176 * the view file corresponding to a relative view name. 對應情景 177 * @return string the view file path. Note that the file may not exist. 文件路徑 178 * @throws InvalidCallException if a relative view name is given while there is no active context to 179 * determine the corresponding view file. 180 */ 181 protected function findViewFile($view, $context = null) 182 { 183 if (strncmp($view, '@', 1) === 0) { 184 // e.g. "@app/views/main" 判斷是否是別名路徑，是則獲取真實路徑 185 $file = Yii::getAlias($view); 186 } elseif (strncmp($view, '//', 2) === 0) { 187 // e.g. "//layouts/main" 以//開始，查找文件路徑，拼接視圖文件路徑 188 $file = Yii::$app->getViewPath() . DIRECTORY_SEPARATOR . ltrim($view, '/'); 189 } elseif (strncmp($view, '/', 1) === 0) { 190 // e.g. "/site/index" 191 if (Yii::$app->controller !== null) { 192 //以/開始，且控制器存在，查找控制器對應的文件目錄，拼接路徑 193 $file = Yii::$app->controller->module->getViewPath() . DIRECTORY_SEPARATOR . ltrim($view, '/'); 194 } else { 195 throw new InvalidCallException("Unable to locate view file for view '$view': no active controller."); 196 } 197 } elseif ($context instanceof ViewContextInterface) { 198 //對應情景存在 查找文件路徑，拼接視圖文件路徑 199 $file = $context->getViewPath() . DIRECTORY_SEPARATOR . $view; 200 } elseif (($currentViewFile = $this->getViewFile()) !== false) { 201 //當前渲染文件存在，拼接路徑 202 $file = dirname($currentViewFile) . DIRECTORY_SEPARATOR . $view; 203 } else { 204 throw new InvalidCallException("Unable to resolve view file for view '$view': no active view context."); 205 } 206 207 if (pathinfo($file, PATHINFO_EXTENSION) !== '') { 208 return $file;//視圖文件的擴展名不為空，返回擴展名 209 } 210 $path = $file . '.' . $this->defaultExtension; //給視圖文件添加擴展名 211 if ($this->defaultExtension !== 'php' && !is_file($path)) { 212 $path = $file . '.php'; 213 } 214 215 return $path;//返回路徑 216 } 217 218 /** 219 * Renders a view file. 220 * 渲染一個視圖文件。 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，將渲染視圖文件的主題版本直到[theme]不可用 224 * The method will call [[FileHelper::localize()]] to localize the view file. 225 * 調用[FileHelper::localize()]方法本地化視圖文件 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]]啟用，該方法將用它來渲染視圖文件。否則，將視圖文件作為一個正常的PHP文件包含進來，獲取其輸出並返回一個字符串。 230 * @param string $viewFile the view file. This can be either an absolute file path or an alias of it. 231 * 視圖文件。可以是絕對路徑或它的別名。 232 * @param array $params the parameters (name-value pairs) that will be extracted and made available in the view file. 233 * 視圖文件執行的參數 234 * @param object $context the context that the view should use for rendering the view. If null, 235 * existing [[context]] will be used. 236 * 用於渲染視圖的上下文 237 * @return string the rendering result 238 * @throws InvalidParamException if the view file does not exist 239 */ 240 public function renderFile($viewFile, $params = [], $context = null) 241 { 242 $viewFile = Yii::getAlias($viewFile);//處理輸入的視圖文件名 243 244 if ($this->theme !== null) { 245 $viewFile = $this->theme->applyTo($viewFile);//如果theme非空，應用到視圖文件 246 } 247 if (is_file($viewFile)) { 248 $viewFile = FileHelper::localize($viewFile);//本地化視圖文件 249 } else { 250 throw new InvalidParamException("The view file does not exist: $viewFile"); 251 } 252 253 $oldContext = $this->context; 254 if ($context !== null) { 255 $this->context = $context; 256 } 257 $output = ''; 258 $this->_viewFiles[] = $viewFile;//記錄當前渲染文件 259 260 if ($this->beforeRender($viewFile, $params)) {//如果前置事件執行成功 261 Yii::trace("Rendering view file: $viewFile", __METHOD__);//記錄trace信息 262 $ext = pathinfo($viewFile, PATHINFO_EXTENSION);//視圖文件擴展名 263 if (isset($this->renderers[$ext])) {//視圖文件的擴展名是否支持 264 if (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];//賦值view渲染器對象 269 $output = $renderer->render($this, $viewFile, $params);//渲染視圖文件 270 } else {//視圖文件不是支持的類型，以普通php文件處理 271 $output = $this->renderPhpFile($viewFile, $params); 272 } 273 $this->afterRender($viewFile, $params, $output); 274 } 275 276 array_pop($this->_viewFiles); 277 $this->context = $oldContext; 278 279 return $output; 280 }
