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 Xue
25 * @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 * 视图模板中共享的自定义参数
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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