View继承了component，用于渲染视图文件：yii2\base\View.php
<span> 1</span> <?<span>php
</span><span> 2</span> <span>/*</span><span>*
</span><span> 3</span> <span> * @link </span><span>http://www.yiiframework.com/</span>
<span> 4</span> <span> * @copyright Copyright (c) 2008 Yii Software LLC
</span><span> 5</span> <span> * @license </span><span>http://www.yiiframework.com/license/</span>
<span> 6</span> <span>*/</span>
<span> 7</span>
<span> 8</span> <span>namespace</span> yii\<span>base</span><span>;
</span><span> 9</span>
<span> 10</span> <span>use Yii;
</span><span> 11</span> <span>use yii\helpers\FileHelper;
</span><span> 12</span> <span>use yii\widgets\Block;
</span><span> 13</span> <span>use yii\widgets\ContentDecorator;
</span><span> 14</span> <span>use yii\widgets\FragmentCache;
</span><span> 15</span>
<span> 16</span> <span>/*</span><span>*
</span><span> 17</span> <span> * View represents a view object in the MVC pattern.
</span><span> 18</span> <span> * MVC中的视图
</span><span> 19</span> <span> * View provides a set of methods (e.g. [[render()]]) for rendering purpose.
</span><span> 20</span> <span> * 视图提供了一套渲染页面的方法
</span><span> 21</span> <span> * @property string|boolean $viewFile The view file currently being rendered. False if no view file is being
</span><span> 22</span> <span> * rendered. This property is read-only.
</span><span> 23</span> <span> *
</span><span> 24</span> <span> * @author Qiang Xue <qiang.xue@gmail.com>
</span><span> 25</span> <span> * @since 2.0
</span><span> 26</span> <span>*/</span>
<span> 27</span> <span>class</span><span> View extends Component
</span><span> 28</span> <span>{
</span><span> 29</span> <span>/*</span><span>*
</span><span> 30</span> <span> * @event Event an event that is triggered by [[beginPage()]].
</span><span> 31</span> <span> * 事件被[beginPage()]触发
</span><span> 32</span> <span>*/</span>
<span> 33</span> <span>const</span> EVENT_BEGIN_PAGE = <span>'</span><span>beginPage</span><span>'</span><span>;
</span><span> 34</span> <span>/*</span><span>*
</span><span> 35</span> <span> * @event Event an event that is triggered by [[endPage()]].
</span><span> 36</span> <span> * 事件被[endPage()]触发
</span><span> 37</span> <span>*/</span>
<span> 38</span> <span>const</span> EVENT_END_PAGE = <span>'</span><span>endPage</span><span>'</span><span>;
</span><span> 39</span> <span>/*</span><span>*
</span><span> 40</span> <span> * @event ViewEvent an event that is triggered by [[renderFile()]] right before it renders a view file.
</span><span> 41</span> <span> * 事件被[renderFile()]触发前呈现一个视图文件
</span><span> 42</span> <span>*/</span>
<span> 43</span> <span>const</span> EVENT_BEFORE_RENDER = <span>'</span><span>beforeRender</span><span>'</span><span>;
</span><span> 44</span> <span>/*</span><span>*
</span><span> 45</span> <span> * @event ViewEvent an event that is triggered by [[renderFile()]] right after it renders a view file.
</span><span> 46</span> <span> * 事件被[renderFile()]触发后呈现一个视图文件
</span><span> 47</span> <span>*/</span>
<span> 48</span> <span>const</span> EVENT_AFTER_RENDER = <span>'</span><span>afterRender</span><span>'</span><span>;
</span><span> 49</span>
<span> 50</span> <span>/*</span><span>*
</span><span> 51</span> <span> * @var ViewContextInterface the context under which the [[renderFile()]] method is being invoked.
</span><span> 52</span> <span> * ViewContextInterface背景下 [renderFile()]方法被调用
</span><span> 53</span> <span>*/</span>
<span> 54</span> <span>public</span><span> $context;
</span><span> 55</span> <span>/*</span><span>*
</span><span> 56</span> <span> * @var mixed custom parameters that are shared among view templates.
</span><span> 57</span> <span> * 视图模板中共享的自定义参数
</span><span> 58</span> <span>*/</span>
<span> 59</span> <span>public</span> $<span>params</span> =<span> [];
</span><span> 60</span> <span>/*</span><span>*
</span><span> 61</span> <span> * @var array a list of available renderers indexed by their corresponding supported file extensions.
</span><span> 62</span> <span> * Each renderer may be a view renderer object or the configuration for creating the renderer object.
</span><span> 63</span> <span> * 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
</span><span> 64</span> <span> * For example, the following configuration enables both Smarty and Twig view renderers:
</span><span> 65</span> <span> *
</span><span> 66</span> <span> * ~~~
</span><span> 67</span> <span> * [
</span><span> 68</span> <span> * 'tpl' => ['class' => 'yii\smarty\ViewRenderer'],
</span><span> 69</span> <span> * 'twig' => ['class' => 'yii\twig\ViewRenderer'],
</span><span> 70</span> <span> * ]
</span><span> 71</span> <span> * ~~~
</span><span> 72</span> <span> *
</span><span> 73</span> <span> * If no renderer is available for the given view file, the view file will be treated as a normal PHP
</span><span> 74</span> <span> * and rendered via [[renderPhpFile()]].
</span><span> 75</span> <span>*/</span>
<span> 76</span> <span>public</span><span> $renderers;
</span><span> 77</span> <span>/*</span><span>*
</span><span> 78</span> <span> * @var string the default view file extension. This will be appended to view file names if they don't have file extensions.
</span><span> 79</span> <span> * 默认视图文件扩展名，文件没有扩展名的情况下自动加载
</span><span> 80</span> <span>*/</span>
<span> 81</span> <span>public</span> $defaultExtension = <span>'</span><span>php</span><span>'</span><span>;
</span><span> 82</span> <span>/*</span><span>*
</span><span> 83</span> <span> * @var Theme|array|string the theme object or the configuration for creating the theme object.
</span><span> 84</span> <span> * 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
</span><span> 85</span> <span>*/</span>
<span> 86</span> <span>public</span><span> $theme;
</span><span> 87</span> <span>/*</span><span>*
</span><span> 88</span> <span> * @var array a list of named output blocks. The keys are the block names and the values
</span><span> 89</span> <span> * are the corresponding block content. You can call [[beginBlock()]] and [[endBlock()]]
</span><span> 90</span> <span> * to capture small fragments of a view. They can be later accessed somewhere else
</span><span> 91</span> <span> * through this property.
</span><span> 92</span> <span> * 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
</span><span> 93</span> <span> * 可以在其他地方通过这个属性访问。
</span><span> 94</span> <span>*/</span>
<span> 95</span> <span>public</span><span> $blocks;
</span><span> 96</span> <span>/*</span><span>*
</span><span> 97</span> <span> * @var array a list of currently active fragment cache widgets. This property
</span><span> 98</span> <span> * is used internally to implement the content caching feature. Do not modify it directly.
</span><span> 99</span> <span> * 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
</span><span>100</span> <span> * @internal
</span><span>101</span> <span>*/</span>
<span>102</span> <span>public</span> $cacheStack =<span> [];
</span><span>103</span> <span>/*</span><span>*
</span><span>104</span> <span> * @var array a list of placeholders for embedding dynamic contents. This property
</span><span>105</span> <span> * is used internally to implement the content caching feature. Do not modify it directly.
</span><span>106</span> <span> * 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
</span><span>107</span> <span> * @internal
</span><span>108</span> <span>*/</span>
<span>109</span> <span>public</span> $dynamicPlaceholders =<span> [];
</span><span>110</span>
<span>111</span> <span>/*</span><span>*
</span><span>112</span> <span> * @var array the view files currently being rendered. There may be multiple view files being
</span><span>113</span> <span> * rendered at a moment because one view may be rendered within another.
</span><span>114</span> <span> * 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
</span><span>115</span> <span>*/</span>
<span>116</span> <span>private</span> $_viewFiles =<span> [];
</span><span>117</span>
<span>118</span>
<span>119</span> <span>/*</span><span>*
</span><span>120</span> <span> * Initializes the view component.初始化视图组件
</span><span>121</span> <span>*/</span>
<span>122</span> <span>public</span><span> function init()
</span><span>123</span> <span> {
</span><span>124</span> parent::init(); <span>//</span><span>调用父类的方法</span>
<span>125</span> <span>if</span> (is_array($<span>this</span>-><span>theme)) {
</span><span>126</span> <span>if</span> (!isset($<span>this</span>->theme[<span>'</span><span>class</span><span>'</span><span>])) {
</span><span>127</span> $<span>this</span>->theme[<span>'</span><span>class</span><span>'</span>] = <span>'</span><span>yii\base\Theme</span><span>'</span>;<span>//</span><span>是数组，没有设置类名，则类名'yii\base\Theme'</span>
<span>128</span> <span> }
</span><span>129</span> $<span>this</span>->theme = Yii::createObject($<span>this</span>->theme);<span>//</span><span>设置了类名，调用配置创建对象</span>
<span>130</span> } elseif (is_string($<span>this</span>->theme)) {<span>//</span><span>以字符串参数的形式创建对象</span>
<span>131</span> $<span>this</span>->theme = Yii::createObject($<span>this</span>-><span>theme);
</span><span>132</span> <span> }
</span><span>133</span> <span> }
</span><span>134</span>
<span>135</span> <span>/*</span><span>*
</span><span>136</span> <span> * Renders a view.
</span><span>137</span> <span> * 渲染一个视图
</span><span>138</span> <span> * The view to be rendered can be specified in one of the following formats:
</span><span>139</span> <span> *
</span><span>140</span> <span> * - path alias (e.g. "@app/views/site/index");
</span><span>141</span> <span> * 路径别名
</span><span>142</span> <span> * - absolute path within application (e.g. "//site/index"): the view name starts with double slashes.
</span><span>143</span> <span> * The actual view file will be looked for under the [[Application::viewPath|view path]] of the application.
</span><span>144</span> <span> * 绝对路径，会在[Application::viewPath|view path]下查找文件
</span><span>145</span> <span> * - absolute path within current module (e.g. "/site/index"): the view name starts with a single slash.
</span><span>146</span> <span> * The actual view file will be looked for under the [[Module::viewPath|view path]] of the [[Controller::module|current module]].
</span><span>147</span> <span> * 模块下的绝对路径，会在[Module::viewPath|view path]下查找文件
</span><span>148</span> <span> * - relative view (e.g. "index"): the view name does not start with `@` or `/`. The corresponding view file will be
</span><span>149</span> <span> * looked for under the [[ViewContextInterface::getViewPath()|view path]] of the view `$context`.
</span><span>150</span> <span> * 相对路径，会在[ViewContextInterface::getViewPath()|view path]下查找文件
</span><span>151</span> <span> * If `$context` is not given, it will be looked for under the directory containing the view currently
</span><span>152</span> <span> * being rendered (i.e., this happens when rendering a view within another view).
</span><span>153</span> <span> *
</span><span>154</span> <span> * @param string $view the view name. 视图名称
</span><span>155</span> <span> * @param array $params the parameters (name-value pairs) that will be extracted and made available in the view file.
</span><span>156</span> <span> * 视图中应用参数
</span><span>157</span> <span> * @param object $context the context to be assigned to the view and can later be accessed via [[context]]
</span><span>158</span> <span> * in the view. If the context implements [[ViewContextInterface]], it may also be used to locate
</span><span>159</span> <span> * the view file corresponding to a relative view name. 对应情景
</span><span>160</span> <span> * @return string the rendering result
</span><span>161</span> <span> * @throws InvalidParamException if the view cannot be resolved or the view file does not exist.
</span><span>162</span> <span> * @see renderFile()
</span><span>163</span> <span>*/</span>
<span>164</span> <span>public</span> function render($view, $<span>params</span> = [], $context = <span>null</span><span>)
</span><span>165</span> <span> {
</span><span>166</span> $viewFile = $<span>this</span>->findViewFile($view, $context);<span>//</span><span>查找视图文件路径</span>
<span>167</span> <span>return</span> $<span>this</span>->renderFile($viewFile, $<span>params</span>, $context);<span>//</span><span>渲染视图文件</span>
<span>168</span> <span> }
</span><span>169</span>
<span>170</span> <span>/*</span><span>*
</span><span>171</span> <span> * Finds the view file based on the given view name.通过视图文件名查找视图文件
</span><span>172</span> <span> * @param string $view the view name or the path alias of the view file. Please refer to [[render()]]
</span><span>173</span> <span> * on how to specify this parameter. 视图名称或路径视图文件的别名
</span><span>174</span> <span> * @param object $context the context to be assigned to the view and can later be accessed via [[context]]
</span><span>175</span> <span> * in the view. If the context implements [[ViewContextInterface]], it may also be used to locate
</span><span>176</span> <span> * the view file corresponding to a relative view name. 对应情景
</span><span>177</span> <span> * @return string the view file path. Note that the file may not exist. 文件路径
</span><span>178</span> <span> * @throws InvalidCallException if a relative view name is given while there is no active context to
</span><span>179</span> <span> * determine the corresponding view file.
</span><span>180</span> <span>*/</span>
<span>181</span> <span>protected</span> function findViewFile($view, $context = <span>null</span><span>)
</span><span>182</span> <span> {
</span><span>183</span> <span>if</span> (strncmp($view, <span>'</span><span>@</span><span>'</span>, <span>1</span>) === <span>0</span><span>) {
</span><span>184</span> <span>//</span><span> e.g. "@app/views/main" 判断是否是别名路径，是则获取真实路径</span>
<span>185</span> $file =<span> Yii::getAlias($view);
</span><span>186</span> } elseif (strncmp($view, <span>'</span><span>//</span><span>'</span>, <span>2</span>) === <span>0</span><span>) {
</span><span>187</span> <span>//</span><span> e.g. "</span><span>//</span><span>layouts/main" 以</span><span>//</span><span>开始，查找文件路径，拼接视图文件路径</span>
<span>188</span> $file = Yii::$app->getViewPath() . DIRECTORY_SEPARATOR . ltrim($view, <span>'</span><span>/</span><span>'</span><span>);
</span><span>189</span> } elseif (strncmp($view, <span>'</span><span>/</span><span>'</span>, <span>1</span>) === <span>0</span><span>) {
</span><span>190</span> <span>//</span><span> e.g. "/site/index"</span>
<span>191</span> <span>if</span> (Yii::$app->controller !== <span>null</span><span>) {
</span><span>192</span> <span>//</span><span>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</span>
<span>193</span> $file = Yii::$app->controller->module->getViewPath() . DIRECTORY_SEPARATOR . ltrim($view, <span>'</span><span>/</span><span>'</span><span>);
</span><span>194</span> } <span>else</span><span> {
</span><span>195</span> <span>throw</span> <span>new</span> InvalidCallException(<span>"</span><span>Unable to locate view file for view '$view': no active controller.</span><span>"</span><span>);
</span><span>196</span> <span> }
</span><span>197</span> <span> } elseif ($context instanceof ViewContextInterface) {
</span><span>198</span> <span>//</span><span>对应情景存在 查找文件路径，拼接视图文件路径</span>
<span>199</span> $file = $context-><span>getViewPath() . DIRECTORY_SEPARATOR . $view;
</span><span>200</span> } elseif (($currentViewFile = $<span>this</span>->getViewFile()) !== <span>false</span><span>) {
</span><span>201</span> <span>//</span><span>当前渲染文件存在，拼接路径</span>
<span>202</span> $file =<span> dirname($currentViewFile) . DIRECTORY_SEPARATOR . $view;
</span><span>203</span> } <span>else</span><span> {
</span><span>204</span> <span>throw</span> <span>new</span> InvalidCallException(<span>"</span><span>Unable to resolve view file for view '$view': no active view context.</span><span>"</span><span>);
</span><span>205</span> <span> }
</span><span>206</span>
<span>207</span> <span>if</span> (pathinfo($file, PATHINFO_EXTENSION) !== <span>''</span><span>) {
</span><span>208</span> <span>return</span> $file;<span>//</span><span>视图文件的扩展名不为空，返回扩展名</span>
<span>209</span> <span> }
</span><span>210</span> $path = $file . <span>'</span><span>.</span><span>'</span> . $<span>this</span>->defaultExtension; <span>//</span><span>给视图文件添加扩展名</span>
<span>211</span> <span>if</span> ($<span>this</span>->defaultExtension !== <span>'</span><span>php</span><span>'</span> && !<span>is_file($path)) {
</span><span>212</span> $path = $file . <span>'</span><span>.php</span><span>'</span><span>;
</span><span>213</span> <span> }
</span><span>214</span>
<span>215</span> <span>return</span> $path;<span>//</span><span>返回路径</span>
<span>216</span> <span> }
</span><span>217</span>
<span>218</span> <span>/*</span><span>*
</span><span>219</span> <span> * Renders a view file.
</span><span>220</span> <span> * 渲染一个视图文件。
</span><span>221</span> <span> * If [[theme]] is enabled (not null), it will try to render the themed version of the view file as long
</span><span>222</span> <span> * as it is available.
</span><span>223</span> <span> * 如果[theme]可用，将渲染视图文件的主题版本直到[theme]不可用
</span><span>224</span> <span> * The method will call [[FileHelper::localize()]] to localize the view file.
</span><span>225</span> <span> * 调用[FileHelper::localize()]方法本地化视图文件
</span><span>226</span> <span> * If [[renderers|renderer]] is enabled (not null), the method will use it to render the view file.
</span><span>227</span> <span> * Otherwise, it will simply include the view file as a normal PHP file, capture its output and
</span><span>228</span> <span> * return it as a string.
</span><span>229</span> <span> * 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。
</span><span>230</span> <span> * @param string $viewFile the view file. This can be either an absolute file path or an alias of it.
</span><span>231</span> <span> * 视图文件。可以是绝对路径或它的别名。
</span><span>232</span> <span> * @param array $params the parameters (name-value pairs) that will be extracted and made available in the view file.
</span><span>233</span> <span> * 视图文件执行的参数
</span><span>234</span> <span> * @param object $context the context that the view should use for rendering the view. If null,
</span><span>235</span> <span> * existing [[context]] will be used.
</span><span>236</span> <span> * 用于渲染视图的上下文
</span><span>237</span> <span> * @return string the rendering result
</span><span>238</span> <span> * @throws InvalidParamException if the view file does not exist
</span><span>239</span> <span>*/</span>
<span>240</span> <span>public</span> function renderFile($viewFile, $<span>params</span> = [], $context = <span>null</span><span>)
</span><span>241</span> <span> {
</span><span>242</span> $viewFile = Yii::getAlias($viewFile);<span>//</span><span>处理输入的视图文件名</span>
<span>243</span>
<span>244</span> <span>if</span> ($<span>this</span>->theme !== <span>null</span><span>) {
</span><span>245</span> $viewFile = $<span>this</span>->theme->applyTo($viewFile);<span>//</span><span>如果theme非空，应用到视图文件</span>
<span>246</span> <span> }
</span><span>247</span> <span>if</span><span> (is_file($viewFile)) {
</span><span>248</span> $viewFile = FileHelper::localize($viewFile);<span>//</span><span>本地化视图文件</span>
<span>249</span> } <span>else</span><span> {
</span><span>250</span> <span>throw</span> <span>new</span> InvalidParamException(<span>"</span><span>The view file does not exist: $viewFile</span><span>"</span><span>);
</span><span>251</span> <span> }
</span><span>252</span>
<span>253</span> $oldContext = $<span>this</span>-><span>context;
</span><span>254</span> <span>if</span> ($context !== <span>null</span><span>) {
</span><span>255</span> $<span>this</span>->context =<span> $context;
</span><span>256</span> <span> }
</span><span>257</span> $output = <span>''</span><span>;
</span><span>258</span> $<span>this</span>->_viewFiles[] = $viewFile;<span>//</span><span>记录当前渲染文件</span>
<span>259</span>
<span>260</span> <span>if</span> ($<span>this</span>->beforeRender($viewFile, $<span>params</span>)) {<span>//</span><span>如果前置事件执行成功</span>
<span>261</span> Yii::trace(<span>"</span><span>Rendering view file: $viewFile</span><span>"</span>, __METHOD__);<span>//</span><span>记录trace信息</span>
<span>262</span> $ext = pathinfo($viewFile, PATHINFO_EXTENSION);<span>//</span><span>视图文件扩展名</span>
<span>263</span> <span>if</span> (isset($<span>this</span>->renderers[$ext])) {<span>//</span><span>视图文件的扩展名是否支持</span>
<span>264</span> <span>if</span> (is_array($<span>this</span>->renderers[$ext]) || is_string($<span>this</span>-><span>renderers[$ext])) {
</span><span>265</span> $<span>this</span>->renderers[$ext] = Yii::createObject($<span>this</span>-><span>renderers[$ext]);
</span><span>266</span> <span> }
</span><span>267</span> <span>/*</span><span> @var $renderer ViewRenderer </span><span>*/</span>
<span>268</span> $renderer = $<span>this</span>->renderers[$ext];<span>//</span><span>赋值view渲染器对象</span>
<span>269</span> $output = $renderer->render($<span>this</span>, $viewFile, $<span>params</span>);<span>//</span><span>渲染视图文件</span>
<span>270</span> } <span>else</span> {<span>//</span><span>视图文件不是支持的类型，以普通php文件处理</span>
<span>271</span> $output = $<span>this</span>->renderPhpFile($viewFile, $<span>params</span><span>);
</span><span>272</span> <span> }
</span><span>273</span> $<span>this</span>->afterRender($viewFile, $<span>params</span><span>, $output);
</span><span>274</span> <span> }
</span><span>275</span>
<span>276</span> array_pop($<span>this</span>-><span>_viewFiles);
</span><span>277</span> $<span>this</span>->context =<span> $oldContext;
</span><span>278</span>
<span>279</span> <span>return</span><span> $output;
</span><span>280</span> }
![[웹 프런트엔드] Node.js 빠른 시작](https://img.php.cn/upload/course/000/000/067/662b5d34ba7c0227.png)
