yii2源碼學(xué)習(xí)筆記（十八），

View繼承了component，用于渲染視圖文件：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中的視圖
</span><span> 19</span> <span> * View provides a set of methods (e.g. [[render()]]) for rendering purpose.
</span><span> 20</span> <span> * 視圖提供了一套渲染頁(yè)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()]觸發(fā)
</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()]觸發(fā)
</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()]觸發(fā)前呈現(xiàn)一個(gè)視圖文件
</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()]觸發(fā)后呈現(xiàn)一個(gè)視圖文件
</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()]方法被調(diào)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>     * 視圖模板中共享的自定義參數(shù)
</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>     *  一個(gè)可用的渲染索引列表。每個(gè)渲染器是一個(gè)渲染器對(duì)象或創(chuàng)建渲染對(duì)象配置數(shù)組
</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>     * 默認(rèn)視圖文件擴(kuò)展名，文件沒(méi)有擴(kuò)展名的情況下自動(dòng)加載
</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.主題對(duì)象或創(chuàng)建主題對(duì)象的配置 未設(shè)置則不啟用
</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>     * 一個(gè)輸出塊列表。鍵是塊名稱(chēng)值為內(nèi)容?？梢哉{(diào)用 [beginblock()]和[endblock()]捕獲視圖的小片段
</span><span> 93</span> <span>     * 可以在其他地方通過(guò)這個(gè)屬性訪問(wèn)。
</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>     * 當(dāng)前操作片段的緩存部件列表。用于內(nèi)部實(shí)現(xiàn)內(nèi)容緩存功能。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>     * 嵌入動(dòng)態(tài)內(nèi)容占位符列表。 用于內(nèi)部實(shí)現(xiàn)內(nèi)容緩存功能。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>     * 正在渲染的視圖文件?？赡苡卸鄠€(gè)視圖文件被渲染，因?yàn)橐粋€(gè)視圖可以在另一個(gè)視圖中呈現(xiàn)
</span><span>115</span>      <span>*/</span>
<span>116</span>     <span>private</span> $_viewFiles =<span> [];
</span><span>117</span> 
<span>118</span> 
<span>119</span>     <span>/*</span><span>*
</span><span>120</span> <span>     * Initializes the view component.初始化視圖組件
</span><span>121</span>      <span>*/</span>
<span>122</span>     <span>public</span><span> function init()
</span><span>123</span> <span>    {
</span><span>124</span>         parent::init(); <span>//</span><span>調(diào)用父類(lèi)的方法</span>
<span>125</span>         <span>if</span> (is_array($<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>是數(shù)組，沒(méi)有設(shè)置類(lèi)名，則類(lèi)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>設(shè)置了類(lèi)名，調(diào)用配置創(chuàng)建對(duì)象</span>
<span>130</span>         } elseif (is_string($<span>this</span>->theme)) {<span>//</span><span>以字符串參數(shù)的形式創(chuàng)建對(duì)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>     * 渲染一個(gè)視圖
</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>     * 路徑別名
</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>     *  絕對(duì)路徑，會(huì)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>     * 模塊下的絕對(duì)路徑，會(huì)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 `$context`.
</span><span>150</span> <span>     * 相對(duì)路徑，會(huì)在[ViewContextInterface::getViewPath()|view path]下查找文件  
</span><span>151</span> <span>     * If `$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.   視圖名稱(chēng)
</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>     * 視圖中應(yīng)用參數(shù)
</span><span>157</span> <span>     * @param object $context the context to be assigned to the view and can later be accessed via [[context]]
</span><span>158</span> <span>     * in the view. If the context implements [[ViewContextInterface]], it may also be used to locate
</span><span>159</span> <span>     * the view file corresponding to a relative view name. 對(duì)應(yīng)情景
</span><span>160</span> <span>     * @return string the rendering result
</span><span>161</span> <span>     * @throws InvalidParamException if the view cannot be resolved or the view file does not exist.
</span><span>162</span> <span>     * @see renderFile()
</span><span>163</span>      <span>*/</span>
<span>164</span>     <span>public</span> function render($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>查找視圖文件路徑</span>
<span>167</span>         <span>return</span> $<span>this</span>->renderFile($viewFile, $<span>params</span>, $context);<span>//</span><span>渲染視圖文件</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.通過(guò)視圖文件名查找視圖文件
</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. 視圖名稱(chēng)或路徑視圖文件的別名
</span><span>174</span> <span>     * @param object $context the context to be assigned to the view and can later be accessed via [[context]]
</span><span>175</span> <span>     * in the view. If the context implements [[ViewContextInterface]], it may also be used to locate
</span><span>176</span> <span>     * the view file corresponding to a relative view name. 對(duì)應(yīng)情景
</span><span>177</span> <span>     * @return string the view file path. Note that the file may not exist. 文件路徑
</span><span>178</span> <span>     * @throws InvalidCallException if a relative view name is given while there is no active context to
</span><span>179</span> <span>     * determine the corresponding view file.
</span><span>180</span>      <span>*/</span>
<span>181</span>     <span>protected</span> function findViewFile($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"  判斷是否是別名路徑，是則獲取真實(shí)路徑</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>開(kāi)始，查找文件路徑，拼接視圖文件路徑</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/開(kāi)始，且控制器存在，查找控制器對(duì)應(yīng)的文件目錄，拼接路徑</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>對(duì)應(yīng)情景存在 查找文件路徑，拼接視圖文件路徑</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>當(dāng)前渲染文件存在，拼接路徑</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>視圖文件的擴(kuò)展名不為空，返回?cái)U(kuò)展名</span>
<span>209</span> <span>        }
</span><span>210</span>         $path = $file . <span>'</span><span>.</span><span>'</span> . $<span>this</span>->defaultExtension; <span>//</span><span>給視圖文件添加擴(kuò)展名</span>
<span>211</span>         <span>if</span> ($<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>返回路徑</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>     * 渲染一個(gè)視圖文件。
</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，將渲染視圖文件的主題版本直到[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>     * 調(diào)用[FileHelper::localize()]方法本地化視圖文件
</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]]啟用，該方法將用它來(lái)渲染視圖文件。否則，將視圖文件作為一個(gè)正常的PHP文件包含進(jìn)來(lái)，獲取其輸出并返回一個(gè)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>     * 視圖文件?？梢允墙^對(duì)路徑或它的別名。
</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>     * 視圖文件執(zhí)行的參數(shù)
</span><span>234</span> <span>     * @param object $context the context that the view should use for rendering the view. If null,
</span><span>235</span> <span>     * existing [[context]] will be used.
</span><span>236</span> <span>     * 用于渲染視圖的上下文
</span><span>237</span> <span>     * @return string the rendering result 
</span><span>238</span> <span>     * @throws InvalidParamException if the view file does not exist
</span><span>239</span>      <span>*/</span>
<span>240</span>     <span>public</span> function renderFile($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>處理輸入的視圖文件名</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，應(yīng)用到視圖文件</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>本地化視圖文件</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[] = $viewFile;<span>//</span><span>記錄當(dāng)前渲染文件</span>
<span>259</span> 
<span>260</span>         <span>if</span> ($<span>this</span>->beforeRender($viewFile, $<span>params</span>)) {<span>//</span><span>如果前置事件執(zhí)行成功</span>
<span>261</span>             Yii::trace(<span>"</span><span>Rendering view file: $viewFile</span><span>"</span>, __METHOD__);<span>//</span><span>記錄trace信息</span>
<span>262</span>             $ext = pathinfo($viewFile, PATHINFO_EXTENSION);<span>//</span><span>視圖文件擴(kuò)展名</span>
<span>263</span>             <span>if</span> (isset($<span>this</span>->renderers[$ext])) {<span>//</span><span>視圖文件的擴(kuò)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>賦值view渲染器對(duì)象</span>
<span>269</span>                 $output = $renderer->render($<span>this</span>, $viewFile, $<span>params</span>);<span>//</span><span>渲染視圖文件</span>
<span>270</span>             } <span>else</span> {<span>//</span><span>視圖文件不是支持的類(lèi)型，以普通php文件處理</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>     }

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