application是所有应用程序类的基类，接下来了解一下它的源码。yii2asepplication.php。
<span style="color: #008080;"> 1</span> <?<span style="color: #000000;">php
</span><span style="color: #008080;"> 2</span> <span style="color: #008000;">/*</span><span style="color: #008000;">*
</span><span style="color: #008080;"> 3</span> <span style="color: #008000;"> * @link </span><span style="color: #008000; text-decoration: underline;">http://www.yiiframework.com/</span>
<span style="color: #008080;"> 4</span> <span style="color: #008000;"> * @copyright Copyright (c) 2008 Yii Software LLC
</span><span style="color: #008080;"> 5</span> <span style="color: #008000;"> * @license </span><span style="color: #008000; text-decoration: underline;">http://www.yiiframework.com/license/</span>
<span style="color: #008080;"> 6</span> <span style="color: #008000;">*/</span>
<span style="color: #008080;"> 7</span>
<span style="color: #008080;"> 8</span> <span style="color: #0000ff;">namespace</span> yii<span style="color: #0000ff;">base</span><span style="color: #000000;">;
</span><span style="color: #008080;"> 9</span>
<span style="color: #008080;"> 10</span> <span style="color: #000000;">use Yii;
</span><span style="color: #008080;"> 11</span>
<span style="color: #008080;"> 12</span> <span style="color: #008000;">/*</span><span style="color: #008000;">*
</span><span style="color: #008080;"> 13</span> <span style="color: #008000;"> * Application is the base class for all application classes.
</span><span style="color: #008080;"> 14</span> <span style="color: #008000;"> * 是所有应用程序类的基类
</span><span style="color: #008080;"> 15</span> <span style="color: #008000;"> * @property yiiwebAssetManager $assetManager The asset manager application component. This property is
</span><span style="color: #008080;"> 16</span> <span style="color: #008000;"> * read-only.资产管理器应用组件，只读
</span><span style="color: #008080;"> 17</span> <span style="color: #008000;"> * @property yii
bacManagerInterface $authManager The auth manager application component. Null is returned
</span><span style="color: #008080;"> 18</span> <span style="color: #008000;"> * if auth manager is not configured. This property is read-only.认证管理器应用程序组件。未配置返回null，只读
</span><span style="color: #008080;"> 19</span> <span style="color: #008000;"> * @property string $basePath The root directory of the application. 应用程序的根目录。
</span><span style="color: #008080;"> 20</span> <span style="color: #008000;"> * @property yiicachingCache $cache The cache application component. Null if the component is not enabled.
</span><span style="color: #008080;"> 21</span> <span style="color: #008000;"> * This property is read-only.缓存应用程序组件。
</span><span style="color: #008080;"> 22</span> <span style="color: #008000;"> * @property yiidbConnection $db The database connection. This property is read-only.数据库连接。
</span><span style="color: #008080;"> 23</span> <span style="color: #008000;"> * @property yiiwebErrorHandler|yiiconsoleErrorHandler $errorHandler The error handler application
</span><span style="color: #008080;"> 24</span> <span style="color: #008000;"> * component. This property is read-only.错误处理程序应用程序组件
</span><span style="color: #008080;"> 25</span> <span style="color: #008000;"> * @property yiii18nFormatter $formatter The formatter application component. This property is read-only.
</span><span style="color: #008080;"> 26</span> <span style="color: #008000;"> * 格式化程序的应用程序组件。
</span><span style="color: #008080;"> 27</span> <span style="color: #008000;"> * @property yiii18nI18N $i18n The internationalization application component. This property is read-only.
</span><span style="color: #008080;"> 28</span> <span style="color: #008000;"> * 国际化应用组件。
</span><span style="color: #008080;"> 29</span> <span style="color: #008000;"> * @property yiilogDispatcher $log The log dispatcher application component. This property is read-only.
</span><span style="color: #008080;"> 30</span> <span style="color: #008000;"> * 日志调度程序组件。
</span><span style="color: #008080;"> 31</span> <span style="color: #008000;"> * @property yiimailMailerInterface $mailer The mailer application component. This property is read-only.
</span><span style="color: #008080;"> 32</span> <span style="color: #008000;"> * 邮件应用程序组件。
</span><span style="color: #008080;"> 33</span> <span style="color: #008000;"> * @property yiiwebRequest|yiiconsoleRequest $request The request component. This property is read-only.
</span><span style="color: #008080;"> 34</span> <span style="color: #008000;"> * 请求组件。
</span><span style="color: #008080;"> 35</span> <span style="color: #008000;"> * @property yiiwebResponse|yiiconsoleResponse $response The response component. This property is
</span><span style="color: #008080;"> 36</span> <span style="color: #008000;"> * read-only.反应元件。
</span><span style="color: #008080;"> 37</span> <span style="color: #008000;"> * @property string $runtimePath The directory that stores runtime files. Defaults to the "runtime"
</span><span style="color: #008080;"> 38</span> <span style="color: #008000;"> * subdirectory under [[basePath]].存储运行时文件的目录。
</span><span style="color: #008080;"> 39</span> <span style="color: #008000;"> * @property yiiaseSecurity $security The security application component. This property is read-only.
</span><span style="color: #008080;"> 40</span> <span style="color: #008000;"> * 安全应用组件。
</span><span style="color: #008080;"> 41</span> <span style="color: #008000;"> * @property string $timeZone The time zone used by this application.该应用程序使用的时区。
</span><span style="color: #008080;"> 42</span> <span style="color: #008000;"> * @property string $uniqueId The unique ID of the module. This property is read-only.模块的唯一标识。
</span><span style="color: #008080;"> 43</span> <span style="color: #008000;"> * @property yiiwebUrlManager $urlManager The URL manager for this application. This property is read-only.
</span><span style="color: #008080;"> 44</span> <span style="color: #008000;"> * 此应用程序的网址管理器。
</span><span style="color: #008080;"> 45</span> <span style="color: #008000;"> * @property string $vendorPath The directory that stores vendor files. Defaults to "vendor" directory under
</span><span style="color: #008080;"> 46</span> <span style="color: #008000;"> * [[basePath]].存储供应商文件的目录。
</span><span style="color: #008080;"> 47</span> <span style="color: #008000;"> * @property View|yiiwebView $view The view application component that is used to render various view
</span><span style="color: #008080;"> 48</span> <span style="color: #008000;"> * files. This property is read-only.用于呈现各种视图文件的视图应用程序组件
</span><span style="color: #008080;"> 49</span> <span style="color: #008000;"> *
</span><span style="color: #008080;"> 50</span> <span style="color: #008000;"> * @author Qiang Xue <qiang.xue@gmail.com>
</span><span style="color: #008080;"> 51</span> <span style="color: #008000;"> * @since 2.0
</span><span style="color: #008080;"> 52</span> <span style="color: #008000;">*/</span>
<span style="color: #008080;"> 53</span> <span style="color: #0000ff;">abstract</span> <span style="color: #0000ff;">class</span><span style="color: #000000;"> Application extends Module
</span><span style="color: #008080;"> 54</span> <span style="color: #000000;">{
</span><span style="color: #008080;"> 55</span> <span style="color: #008000;">/*</span><span style="color: #008000;">*
</span><span style="color: #008080;"> 56</span> <span style="color: #008000;"> * @event Event an event raised before the application starts to handle a request.
</span><span style="color: #008080;"> 57</span> <span style="color: #008000;"> * 在应用程序开始处理请求之前提出的事件。
</span><span style="color: #008080;"> 58</span> <span style="color: #008000;">*/</span>
<span style="color: #008080;"> 59</span> <span style="color: #0000ff;">const</span> EVENT_BEFORE_REQUEST = <span style="color: #800000;">'</span><span style="color: #800000;">beforeRequest</span><span style="color: #800000;">'</span><span style="color: #000000;">;
</span><span style="color: #008080;"> 60</span> <span style="color: #008000;">/*</span><span style="color: #008000;">*
</span><span style="color: #008080;"> 61</span> <span style="color: #008000;"> * @event Event an event raised after the application successfully handles a request (before the response is sent out).
</span><span style="color: #008080;"> 62</span> <span style="color: #008000;"> * 该应用程序成功处理请求后提出的事件
</span><span style="color: #008080;"> 63</span> <span style="color: #008000;">*/</span>
<span style="color: #008080;"> 64</span> <span style="color: #0000ff;">const</span> EVENT_AFTER_REQUEST = <span style="color: #800000;">'</span><span style="color: #800000;">afterRequest</span><span style="color: #800000;">'</span><span style="color: #000000;">;
</span><span style="color: #008080;"> 65</span> <span style="color: #008000;">/*</span><span style="color: #008000;">*
</span><span style="color: #008080;"> 66</span> <span style="color: #008000;"> * Application state used by [[state]]: application just started.
</span><span style="color: #008080;"> 67</span> <span style="color: #008000;"> * [[state]]适用状态：刚开始应用
</span><span style="color: #008080;"> 68</span> <span style="color: #008000;">*/</span>
<span style="color: #008080;"> 69</span> <span style="color: #0000ff;">const</span> STATE_BEGIN = <span style="color: #800080;">0</span><span style="color: #000000;">;
</span><span style="color: #008080;"> 70</span> <span style="color: #008000;">/*</span><span style="color: #008000;">*
</span><span style="color: #008080;"> 71</span> <span style="color: #008000;"> * Application state used by [[state]]: application is initializing.
</span><span style="color: #008080;"> 72</span> <span style="color: #008000;"> * [[state]]应用程序状态：应用程序初始化。
</span><span style="color: #008080;"> 73</span> <span style="color: #008000;">*/</span>
<span style="color: #008080;"> 74</span> <span style="color: #0000ff;">const</span> STATE_INIT = <span style="color: #800080;">1</span><span style="color: #000000;">;
</span><span style="color: #008080;"> 75</span> <span style="color: #008000;">/*</span><span style="color: #008000;">*
</span><span style="color: #008080;"> 76</span> <span style="color: #008000;"> * Application state used by [[state]]: application is triggering [[EVENT_BEFORE_REQUEST]].
</span><span style="color: #008080;"> 77</span> <span style="color: #008000;"> * [[state]]应用程序状态：应用触发[[EVENT_BEFORE_REQUEST]]
</span><span style="color: #008080;"> 78</span> <span style="color: #008000;">*/</span>
<span style="color: #008080;"> 79</span> <span style="color: #0000ff;">const</span> STATE_BEFORE_REQUEST = <span style="color: #800080;">2</span><span style="color: #000000;">;
</span><span style="color: #008080;"> 80</span> <span style="color: #008000;">/*</span><span style="color: #008000;">*
</span><span style="color: #008080;"> 81</span> <span style="color: #008000;"> * Application state used by [[state]]: application is handling the request.
</span><span style="color: #008080;"> 82</span> <span style="color: #008000;"> * [[state]]应用程序状态：应用程序处理请求。
</span><span style="color: #008080;"> 83</span> <span style="color: #008000;">*/</span>
<span style="color: #008080;"> 84</span> <span style="color: #0000ff;">const</span> STATE_HANDLING_REQUEST = <span style="color: #800080;">3</span><span style="color: #000000;">;
</span><span style="color: #008080;"> 85</span> <span style="color: #008000;">/*</span><span style="color: #008000;">*
</span><span style="color: #008080;"> 86</span> <span style="color: #008000;"> * Application state used by [[state]]: application is triggering [[EVENT_AFTER_REQUEST]]..
</span><span style="color: #008080;"> 87</span> <span style="color: #008000;"> * [[state]]应用程序状态：应用触发[[EVENT_AFTER_REQUEST]]
</span><span style="color: #008080;"> 88</span> <span style="color: #008000;">*/</span>
<span style="color: #008080;"> 89</span> <span style="color: #0000ff;">const</span> STATE_AFTER_REQUEST = <span style="color: #800080;">4</span><span style="color: #000000;">;
</span><span style="color: #008080;"> 90</span> <span style="color: #008000;">/*</span><span style="color: #008000;">*
</span><span style="color: #008080;"> 91</span> <span style="color: #008000;"> * Application state used by [[state]]: application is about to send response.
</span><span style="color: #008080;"> 92</span> <span style="color: #008000;"> * [[state]]应用程序状态：应用程序即将发送响应。
</span><span style="color: #008080;"> 93</span> <span style="color: #008000;">*/</span>
<span style="color: #008080;"> 94</span> <span style="color: #0000ff;">const</span> STATE_SENDING_RESPONSE = <span style="color: #800080;">5</span><span style="color: #000000;">;
</span><span style="color: #008080;"> 95</span> <span style="color: #008000;">/*</span><span style="color: #008000;">*
</span><span style="color: #008080;"> 96</span> <span style="color: #008000;"> * Application state used by [[state]]: application has ended.
</span><span style="color: #008080;"> 97</span> <span style="color: #008000;"> * [[state]]应用程序状态：应用程序结束。
</span><span style="color: #008080;"> 98</span> <span style="color: #008000;">*/</span>
<span style="color: #008080;"> 99</span> <span style="color: #0000ff;">const</span> STATE_END = <span style="color: #800080;">6</span><span style="color: #000000;">;
</span><span style="color: #008080;">100</span>
<span style="color: #008080;">101</span> <span style="color: #008000;">/*</span><span style="color: #008000;">*
</span><span style="color: #008080;">102</span> <span style="color: #008000;"> * @var string the namespace that controller classes are located in.控制器类的命名空间位置。
</span><span style="color: #008080;">103</span> <span style="color: #008000;"> * This namespace will be used to load controller classes by prepending it to the controller class name.
</span><span style="color: #008080;">104</span> <span style="color: #008000;"> * The default namespace is `appcontrollers`.
</span><span style="color: #008080;">105</span> <span style="color: #008000;"> * 此命名空间将用于负载控制器类重写它的控制器类的名字。 默认命名空间是`appcontrollers`。
</span><span style="color: #008080;">106</span> <span style="color: #008000;"> * Please refer to the [guide about class autoloading](guide:concept-autoloading.md) for more details.
</span><span style="color: #008080;">107</span> <span style="color: #008000;">*/</span>
<span style="color: #008080;">108</span> <span style="color: #0000ff;">public</span> $controllerNamespace = <span style="color: #800000;">'</span><span style="color: #800000;">app\controllers</span><span style="color: #800000;">'</span><span style="color: #000000;">;
</span><span style="color: #008080;">109</span> <span style="color: #008000;">/*</span><span style="color: #008000;">*
</span><span style="color: #008080;">110</span> <span style="color: #008000;"> * @var string the application name.应用程序名称。
</span><span style="color: #008080;">111</span> <span style="color: #008000;">*/</span>
<span style="color: #008080;">112</span> <span style="color: #0000ff;">public</span> $name = <span style="color: #800000;">'</span><span style="color: #800000;">My Application</span><span style="color: #800000;">'</span><span style="color: #000000;">;
</span><span style="color: #008080;">113</span> <span style="color: #008000;">/*</span><span style="color: #008000;">*
</span><span style="color: #008080;">114</span> <span style="color: #008000;"> * @var string the version of this application.此应用程序的版本。
</span><span style="color: #008080;">115</span> <span style="color: #008000;">*/</span>
<span style="color: #008080;">116</span> <span style="color: #0000ff;">public</span> $version = <span style="color: #800000;">'</span><span style="color: #800000;">1.0</span><span style="color: #800000;">'</span><span style="color: #000000;">;
</span><span style="color: #008080;">117</span> <span style="color: #008000;">/*</span><span style="color: #008000;">*
</span><span style="color: #008080;">118</span> <span style="color: #008000;"> * @var string the charset currently used for the application.目前使用的字符集。
</span><span style="color: #008080;">119</span> <span style="color: #008000;">*/</span>
<span style="color: #008080;">120</span> <span style="color: #0000ff;">public</span> $charset = <span style="color: #800000;">'</span><span style="color: #800000;">UTF-8</span><span style="color: #800000;">'</span><span style="color: #000000;">;
</span><span style="color: #008080;">121</span> <span style="color: #008000;">/*</span><span style="color: #008000;">*
</span><span style="color: #008080;">122</span> <span style="color: #008000;"> * @var string the language that is meant to be used for end users. It is recommended that you
</span><span style="color: #008080;">123</span> <span style="color: #008000;"> * use [IETF language tags](</span><span style="color: #008000; text-decoration: underline;">http://en.wikipedia.org/wiki/IETF_language_tag</span><span style="color: #008000;">). For example, `en` stands
</span><span style="color: #008080;">124124</span> <span style="color: #008000;"> * for English, while `en-US` stands for English (United States).
</span><span style="color: #008080;">125</span> <span style="color: #008000;"> * 用来作为终端用户使用的语言
</span><span style="color: #008080;">126</span> <span style="color: #008000;"> * @see sourceLanguage
</span><span style="color: #008080;">127</span> <span style="color: #008000;">*/</span>
<span style="color: #008080;">128</span> <span style="color: #0000ff;">public</span> $language = <span style="color: #800000;">'</span><span style="color: #800000;">en-US</span><span style="color: #800000;">'</span><span style="color: #000000;">;
</span><span style="color: #008080;">129</span> <span style="color: #008000;">/*</span><span style="color: #008000;">*
</span><span style="color: #008080;">130</span> <span style="color: #008000;"> * @var string the language that the application is written in. This mainly refers to
</span><span style="color: #008080;">131</span> <span style="color: #008000;"> * the language that the messages and view files are written in.
</span><span style="color: #008080;">132</span> <span style="color: #008000;"> * 应用程序编写的语言。
</span><span style="color: #008080;">133</span> <span style="color: #008000;"> * @see language
</span><span style="color: #008080;">134</span> <span style="color: #008000;">*/</span>
<span style="color: #008080;">135</span> <span style="color: #0000ff;">public</span> $sourceLanguage = <span style="color: #800000;">'</span><span style="color: #800000;">en-US</span><span style="color: #800000;">'</span><span style="color: #000000;">;
</span><span style="color: #008080;">136</span> <span style="color: #008000;">/*</span><span style="color: #008000;">*
</span><span style="color: #008080;">137</span> <span style="color: #008000;"> * @var Controller the currently active controller instance当前活动控制器实例
</span><span style="color: #008080;">138</span> <span style="color: #008000;">*/</span>
<span style="color: #008080;">139</span> <span style="color: #0000ff;">public</span><span style="color: #000000;"> $controller;
</span><span style="color: #008080;">140</span> <span style="color: #008000;">/*</span><span style="color: #008000;">*
</span><span style="color: #008080;">141</span> <span style="color: #008000;"> * @var string|boolean the layout that should be applied for views in this application. Defaults to 'main'.
</span><span style="color: #008080;">142</span> <span style="color: #008000;"> * If this is false, layout will be disabled.
</span><span style="color: #008080;">143</span> <span style="color: #008000;"> * 该应用程序中应用的布局。
</span><span style="color: #008080;">144</span> <span style="color: #008000;">*/</span>
<span style="color: #008080;">145</span> <span style="color: #0000ff;">public</span> $layout = <span style="color: #800000;">'</span><span style="color: #800000;">main</span><span style="color: #800000;">'</span><span style="color: #000000;">;
</span><span style="color: #008080;">146</span> <span style="color: #008000;">/*</span><span style="color: #008000;">*
</span><span style="color: #008080;">147</span> <span style="color: #008000;"> * @var string the requested route请求的路径 请求的路径
</span><span style="color: #008080;">148</span> <span style="color: #008000;">*/</span>
<span style="color: #008080;">149</span> <span style="color: #0000ff;">public</span><span style="color: #000000;"> $requestedRoute;
</span><span style="color: #008080;">150</span> <span style="color: #008000;">/*</span><span style="color: #008000;">*
</span><span style="color: #008080;">151</span> <span style="color: #008000;"> * @var Action the requested Action. If null, it means the request cannot be resolved into an action.
</span><span style="color: #008080;">152</span> <span style="color: #008000;"> * 操作所要求的行动
</span><span style="color: #008080;">153</span> <span style="color: #008000;">*/</span>
<span style="color: #008080;">154</span> <span style="color: #0000ff;">public</span><span style="color: #000000;"> $requestedAction;
</span><span style="color: #008080;">155</span> <span style="color: #008000;">/*</span><span style="color: #008000;">*
</span><span style="color: #008080;">156</span> <span style="color: #008000;"> * @var array the parameters supplied to the requested action.
</span><span style="color: #008080;">157</span> <span style="color: #008000;"> * 所请求的动作提供的参数。
</span><span style="color: #008080;">158</span> <span style="color: #008000;">*/</span>
<span style="color: #008080;">159</span> <span style="color: #0000ff;">public</span><span style="color: #000000;"> $requestedParams;
</span><span style="color: #008080;">160</span> <span style="color: #008000;">/*</span><span style="color: #008000;">*
</span><span style="color: #008080;">161</span> <span style="color: #008000;"> * @var array list of installed Yii extensions. Each array element represents a single extension
</span><span style="color: #008080;">162</span> <span style="color: #008000;"> * with the following structure:
</span><span style="color: #008080;">163</span> <span style="color: #008000;"> * 安装Yii扩展名列表。每个数组元素代表一个扩展
</span><span style="color: #008080;">164</span> <span style="color: #008000;"> *
</span><span style="color: #008080;">165</span> <span style="color: #008000;"> * ~~~
</span><span style="color: #008080;">166</span> <span style="color: #008000;"> * [
</span><span style="color: #008080;">167</span> <span style="color: #008000;"> * 'name' => 'extension name',
</span><span style="color: #008080;">168</span> <span style="color: #008000;"> * 'version' => 'version number',
</span><span style="color: #008080;">169</span> <span style="color: #008000;"> * 'bootstrap' => 'BootstrapClassName', // optional, may also be a configuration array
</span><span style="color: #008080;">170</span> <span style="color: #008000;"> * 'alias' => [
</span><span style="color: #008080;">171</span> <span style="color: #008000;"> * '@alias1' => 'to/path1',
</span><span style="color: #008080;">172</span> <span style="color: #008000;"> * '@alias2' => 'to/path2',
</span><span style="color: #008080;">173</span> <span style="color: #008000;"> * ],
</span><span style="color: #008080;">174</span> <span style="color: #008000;"> * ]
</span><span style="color: #008080;">175</span> <span style="color: #008000;"> * ~~~
</span><span style="color: #008080;">176</span> <span style="color: #008000;"> *
</span><span style="color: #008080;">177</span> <span style="color: #008000;"> * The "bootstrap" class listed above will be instantiated during the application
</span><span style="color: #008080;">178</span> <span style="color: #008000;"> * [[bootstrap()|bootstrapping process]]. If the class implements [[BootstrapInterface]],
</span><span style="color: #008080;">179</span> <span style="color: #008000;"> * its [[BootstrapInterface::bootstrap()|bootstrap()]] method will be also be called.
</span><span style="color: #008080;">180</span> <span style="color: #008000;"> *
</span><span style="color: #008080;">181</span> <span style="color: #008000;"> * If not set explicitly in the application config, this property will be populated with the contents of
</span><span style="color: #008080;">182</span> <span style="color: #008000;"> * 如果在应用程序配置中没有设置，该属性将填充到内容
</span><span style="color: #008080;">183</span> <span style="color: #008000;"> * @vendor/yiisoft/extensions.php`.
</span><span style="color: #008080;">184</span> <span style="color: #008000;">*/</span>
<span style="color: #008080;">185</span> <span style="color: #0000ff;">public</span><span style="color: #000000;"> $extensions;
</span><span style="color: #008080;">186</span> <span style="color: #008000;">/*</span><span style="color: #008000;">*
</span><span style="color: #008080;">187</span> <span style="color: #008000;"> * @var array list of components that should be run during the application [[bootstrap()|bootstrapping process]].
</span><span style="color: #008080;">188</span> <span style="color: #008000;"> * 组件的列表，运行在 [[bootstrap()|bootstrapping process]]中的应用
</span><span style="color: #008080;">189</span> <span style="color: #008000;"> * Each component may be specified in one of the following formats:
</span><span style="color: #008080;">190</span> <span style="color: #008000;"> *
</span><span style="color: #008080;">191</span> <span style="color: #008000;"> * - an application component ID as specified via [[components]].
</span><span style="color: #008080;">192</span> <span style="color: #008000;"> * - a module ID as specified via [[modules]].
</span><span style="color: #008080;">193</span> <span style="color: #008000;"> * - a class name.
</span><span style="color: #008080;">194</span> <span style="color: #008000;"> * - a configuration array.
</span><span style="color: #008080;">195</span> <span style="color: #008000;"> *
</span><span style="color: #008080;">196</span> <span style="color: #008000;"> * During the bootstrapping process, each component will be instantiated. If the component class
</span><span style="color: #008080;">197</span> <span style="color: #008000;"> * implements [[BootstrapInterface]], its [[BootstrapInterface::bootstrap()|bootstrap()]] method
</span><span style="color: #008080;">198</span> <span style="color: #008000;"> * will be also be called.
</span><span style="color: #008080;">199</span> <span style="color: #008000;"> * 在整个启动过程中，每个组件被实例化。如果组件类提到 [[BootstrapInterface]]，
</span><span style="color: #008080;">200</span> <span style="color: #008000;"> * [[BootstrapInterface::bootstrap()|bootstrap()]]方法也会调用
</span><span style="color: #008080;">201</span> <span style="color: #008000;">*/</span>
<span style="color: #008080;">202</span> <span style="color: #0000ff;">public</span> $bootstrap =<span style="color: #000000;"> [];
</span><span style="color: #008080;">203</span> <span style="color: #008000;">/*</span><span style="color: #008000;">*
</span><span style="color: #008080;">204</span> <span style="color: #008000;"> * @var integer the current application state during a request handling life cycle.
</span><span style="color: #008080;">205</span> <span style="color: #008000;"> * This property is managed by the application. Do not modify this property.
</span><span style="color: #008080;">206</span> <span style="color: #008000;"> * 在请求处理生命周期中的当前应用程序状态。属性由应用程序管理。不要修改此属性。
</span><span style="color: #008080;">207</span> <span style="color: #008000;">*/</span>
<span style="color: #008080;">208</span> <span style="color: #0000ff;">public</span><span style="color: #000000;"> $state;
</span><span style="color: #008080;">209</span> <span style="color: #008000;">/*</span><span style="color: #008000;">*
</span><span style="color: #008080;">210</span> <span style="color: #008000;"> * @var array list of loaded modules indexed by their class names.
</span><span style="color: #008080;">211</span> <span style="color: #008000;"> * 加载模块列表由它们的类名称索引组成。
</span><span style="color: #008080;">212</span> <span style="color: #008000;">*/</span>
<span style="color: #008080;">213</span> <span style="color: #0000ff;">public</span> $loadedModules =<span style="color: #000000;"> [];
</span><span style="color: #008080;">214</span>
<span style="color: #008080;">215</span>
<span style="color: #008080;">216</span> <span style="color: #008000;">/*</span><span style="color: #008000;">*
</span><span style="color: #008080;">217</span> <span style="color: #008000;"> * Constructor.构造函数
</span><span style="color: #008080;">218</span> <span style="color: #008000;"> * @param array $config name-value pairs that will be used to initialize the object properties.
</span><span style="color: #008080;">219</span> <span style="color: #008000;"> * Note that the configuration must contain both [[id]] and [[basePath]].
</span><span style="color: #008080;">220</span> <span style="color: #008000;"> * 用来初始化对象属性的 name-value 注意配置必须包含[[id]] 和[[basePath]].
</span><span style="color: #008080;">221</span> <span style="color: #008000;"> * @throws InvalidConfigException if either [[id]] or [[basePath]] configuration is missing.
</span><span style="color: #008080;">222</span> <span style="color: #008000;"> * 如果是修改[[id]] 或[[basePath]] 则配置丢失。
</span><span style="color: #008080;">223</span> <span style="color: #008000;">*/</span>
<span style="color: #008080;">224</span> <span style="color: #0000ff;">public</span> function __construct($config =<span style="color: #000000;"> [])
</span><span style="color: #008080;">225</span> <span style="color: #000000;"> {
</span><span style="color: #008080;">226</span> Yii::$app = $<span style="color: #0000ff;">this</span>;<span style="color: #008000;">//</span><span style="color: #008000;"> 将自身的实例绑到Yii的$app上</span>
<span style="color: #008080;">227</span> $<span style="color: #0000ff;">this</span>->setInstance($<span style="color: #0000ff;">this</span>);<span style="color: #008000;">//</span><span style="color: #008000;"> 将自身加入到loadedModules中</span>
<span style="color: #008080;">228</span>
<span style="color: #008080;">229</span> $<span style="color: #0000ff;">this</span>->state = self::STATE_BEGIN;<span style="color: #008000;">//</span><span style="color: #008000;"> 设置状态为刚开始
</span><span style="color: #008080;">230</span>
<span style="color: #008080;">231</span> <span style="color: #008000;">//</span><span style="color: #008000;"> 做预处理配置</span>
<span style="color: #008080;">232</span> $<span style="color: #0000ff;">this</span>-><span style="color: #000000;">preInit($config);
</span><span style="color: #008080;">233</span>
<span style="color: #008080;">234</span> $<span style="color: #0000ff;">this</span>-><span style="color: #000000;">registerErrorHandler($config);
</span><span style="color: #008080;">235</span>
<span style="color: #008080;">236</span> <span style="color: #000000;"> Component::__construct($config);
</span><span style="color: #008080;">237</span> <span style="color: #000000;"> }
</span><span style="color: #008080;">238</span>
<span style="color: #008080;">239</span> <span style="color: #008000;">/*</span><span style="color: #008000;">*
</span><span style="color: #008080;">240</span> <span style="color: #008000;"> * Pre-initializes the application. 初始化应用。
</span><span style="color: #008080;">241</span> <span style="color: #008000;"> * This method is called at the beginning of the application constructor.
</span><span style="color: #008080;">242</span> <span style="color: #008000;"> * It initializes several important application properties.
</span><span style="color: #008080;">243</span> <span style="color: #008000;"> * 在构造函数中调用该方法，用于初始化一些重要的属性
</span><span style="color: #008080;">244</span> <span style="color: #008000;"> * If you override this method, please make sure you call the parent implementation.
</span><span style="color: #008080;">245</span> <span style="color: #008000;"> * @param array $config the application configuration 应用的配置
</span><span style="color: #008080;">246</span> <span style="color: #008000;"> * @throws InvalidConfigException if either [[id]] or [[basePath]] configuration is missing.
</span><span style="color: #008080;">247</span> <span style="color: #008000;">*/</span>
<span style="color: #008080;">248</span> <span style="color: #0000ff;">public</span> function preInit(&<span style="color: #000000;">$config)
</span><span style="color: #008080;">249</span> <span style="color: #000000;"> {
</span><span style="color: #008080;">250</span> <span style="color: #008000;">//</span><span style="color: #008000;"> 使用了&符号，表示$config的修改会保留</span>
<span style="color: #008080;">251</span> <span style="color: #0000ff;">if</span> (!isset($config[<span style="color: #800000;">'</span><span style="color: #800000;">id</span><span style="color: #800000;">'</span>])) {<span style="color: #008000;">//</span><span style="color: #008000;">判断配置中是否有application ID ，如果没有，抛出异常</span>
<span style="color: #008080;">252</span> <span style="color: #0000ff;">throw</span> <span style="color: #0000ff;">new</span> InvalidConfigException(<span style="color: #800000;">'</span><span style="color: #800000;">The "id" configuration for the Application is required.</span><span style="color: #800000;">'</span><span style="color: #000000;">);
</span><span style="color: #008080;">253</span> <span style="color: #000000;"> }
</span><span style="color: #008080;">254</span> <span style="color: #0000ff;">if</span> (isset($config[<span style="color: #800000;">'</span><span style="color: #800000;">basePath</span><span style="color: #800000;">'</span><span style="color: #000000;">])) {
</span><span style="color: #008080;">255</span> <span style="color: #008000;">//</span><span style="color: #008000;"> 是否配置项目的root路径</span>
<span style="color: #008080;">256</span> $<span style="color: #0000ff;">this</span>->setBasePath($config[<span style="color: #800000;">'</span><span style="color: #800000;">basePath</span><span style="color: #800000;">'</span><span style="color: #000000;">]);
</span><span style="color: #008080;">257</span> <span style="color: #008000;">//</span><span style="color: #008000;">赋值给模块的_basepath属性，并在设置后删除</span>
<span style="color: #008080;">258</span> unset($config[<span style="color: #800000;">'</span><span style="color: #800000;">basePath</span><span style="color: #800000;">'</span><span style="color: #000000;">]);
</span><span style="color: #008080;">259</span> } <span style="color: #0000ff;">else</span> {<span style="color: #008000;">//</span><span style="color: #008000;">否则抛出异常</span>
<span style="color: #008080;">260</span> <span style="color: #0000ff;">throw</span> <span style="color: #0000ff;">new</span> InvalidConfigException(<span style="color: #800000;">'</span><span style="color: #800000;">The "basePath" configuration for the Application is required.</span><span style="color: #800000;">'</span><span style="color: #000000;">);
</span><span style="color: #008080;">261</span> <span style="color: #000000;"> }
</span><span style="color: #008080;">262</span> <span style="color: #008000;">//</span><span style="color: #008000;">如果配置文件中设置了 vendorPath 使用配置的值，并在设置后删除，否则使用默认的</span>
<span style="color: #008080;">263</span> <span style="color: #0000ff;">if</span> (isset($config[<span style="color: #800000;">'</span><span style="color: #800000;">vendorPath</span><span style="color: #800000;">'</span><span style="color: #000000;">])) {
</span><span style="color: #008080;">264</span> $<span style="color: #0000ff;">this</span>->setVendorPath($config[<span style="color: #800000;">'</span><span style="color: #800000;">vendorPath</span><span style="color: #800000;">'</span><span style="color: #000000;">]);
</span><span style="color: #008080;">265</span> unset($config[<span style="color: #800000;">'</span><span style="color: #800000;">vendorPath</span><span style="color: #800000;">'</span><span style="color: #000000;">]);
</span><span style="color: #008080;">266</span> } <span style="color: #0000ff;">else</span><span style="color: #000000;"> {
</span><span style="color: #008080;">267</span> <span style="color: #008000;">//</span><span style="color: #008000;"> set "@vendor"</span>
<span style="color: #008080;">268</span> $<span style="color: #0000ff;">this</span>-><span style="color: #000000;">getVendorPath();
</span><span style="color: #008080;">269</span> <span style="color: #000000;"> }
</span><span style="color: #008080;">270</span> <span style="color: #008000;">//</span><span style="color: #008000;">如果配置文件中设置了 runtimePath 使用配置的值，并在设置后删除，否则使用默认的</span>
<span style="color: #008080;">271</span> <span style="color: #0000ff;">if</span> (isset($config[<span style="color: #800000;">'</span><span style="color: #800000;">runtimePath</span><span style="color: #800000;">'</span><span style="color: #000000;">])) {
</span><span style="color: #008080;">272</span> $<span style="color: #0000ff;">this</span>->setRuntimePath($config[<span style="color: #800000;">'</span><span style="color: #800000;">runtimePath</span><span style="color: #800000;">'</span><span style="color: #000000;">]);
</span><span style="color: #008080;">273</span> unset($config[<span style="color: #800000;">'</span><span style="color: #800000;">runtimePath</span><span style="color: #800000;">'</span><span style="color: #000000;">]);
</span><span style="color: #008080;">274</span> } <span style="color: #0000ff;">else</span><span style="color: #000000;"> {
</span><span style="color: #008080;">275</span> <span style="color: #008000;">//</span><span style="color: #008000;"> set "@runtime"</span>
<span style="color: #008080;">276</span> $<span style="color: #0000ff;">this</span>-><span style="color: #000000;">getRuntimePath();
</span><span style="color: #008080;">277</span> <span style="color: #000000;"> }
</span><span style="color: #008080;">278</span> <span style="color: #008000;">//</span><span style="color: #008000;">如果配置文件中设置了 timeZone 使用配置的值，并在设置后删除，否则使用默认的时区</span>
<span style="color: #008080;">279</span> <span style="color: #0000ff;">if</span> (isset($config[<span style="color: #800000;">'</span><span style="color: #800000;">timeZone</span><span style="color: #800000;">'</span><span style="color: #000000;">])) {
</span><span style="color: #008080;">280</span> $<span style="color: #0000ff;">this</span>->setTimeZone($config[<span style="color: #800000;">'</span><span style="color: #800000;">timeZone</span><span style="color: #800000;">'</span><span style="color: #000000;">]);
</span><span style="color: #008080;">281</span> unset($config[<span style="color: #800000;">'</span><span style="color: #800000;">timeZone</span><span style="color: #800000;">'</span><span style="color: #000000;">]);
</span><span style="color: #008080;">282</span> } elseif (!ini_get(<span style="color: #800000;">'</span><span style="color: #800000;">date.timezone</span><span style="color: #800000;">'</span><span style="color: #000000;">)) {
</span><span style="color: #008080;">283</span> $<span style="color: #0000ff;">this</span>->setTimeZone(<span style="color: #800000;">'</span><span style="color: #800000;">UTC</span><span style="color: #800000;">'</span><span style="color: #000000;">);
</span><span style="color: #008080;">284</span> <span style="color: #000000;"> }
</span><span style="color: #008080;">285</span>
<span style="color: #008080;">286</span> <span style="color: #008000;">//</span><span style="color: #008000;"> merge core components with custom components</span>
<span style="color: #008080;">287</span> <span style="color: #0000ff;">foreach</span> ($<span style="color: #0000ff;">this</span>->coreComponents() <span style="color: #0000ff;">as</span> $id =><span style="color: #000000;"> $component) {
</span><span style="color: #008080;">288</span> <span style="color: #0000ff;">if</span> (!isset($config[<span style="color: #800000;">'</span><span style="color: #800000;">components</span><span style="color: #800000;">'</span><span style="color: #000000;">][$id])) {
</span><span style="color: #008080;">289</span> <span style="color: #008000;">//</span><span style="color: #008000;"> 如果配置中没有配置相应的核心component，就赋给它</span>
<span style="color: #008080;">290</span> $config[<span style="color: #800000;">'</span><span style="color: #800000;">components</span><span style="color: #800000;">'</span>][$id] =<span style="color: #000000;"> $component;
</span><span style="color: #008080;">291</span> } elseif (is_array($config[<span style="color: #800000;">'</span><span style="color: #800000;">components</span><span style="color: #800000;">'</span>][$id]) && !isset($config[<span style="color: #800000;">'</span><span style="color: #800000;">components</span><span style="color: #800000;">'</span>][$id][<span style="color: #800000;">'</span><span style="color: #800000;">class</span><span style="color: #800000;">'</span><span style="color: #000000;">])) {
</span><span style="color: #008080;">292</span> <span style="color: #008000;">//</span><span style="color: #008000;"> 如果存在相应的核心component，但没有定义它的class，就直接赋到class的key上</span>
<span style="color: #008080;">293</span> $config[<span style="color: #800000;">'</span><span style="color: #800000;">components</span><span style="color: #800000;">'</span>][$id][<span style="color: #800000;">'</span><span style="color: #800000;">class</span><span style="color: #800000;">'</span>] = $component[<span style="color: #800000;">'</span><span style="color: #800000;">class</span><span style="color: #800000;">'</span><span style="color: #000000;">];
</span><span style="color: #008080;">294</span> <span style="color: #000000;"> }
</span><span style="color: #008080;">295</span> <span style="color: #000000;"> }
</span><span style="color: #008080;">296</span> <span style="color: #000000;"> }
</span><span style="color: #008080;">297</span>
<span style="color: #008080;">298</span> <span style="color: #008000;">/*</span><span style="color: #008000;">*
</span><span style="color: #008080;">299</span> <span style="color: #008000;"> * @inheritdoc
</span><span style="color: #008080;">300</span> <span style="color: #008000;">*/</span>
<span style="color: #008080;">301</span> <span style="color: #0000ff;">public</span><span style="color: #000000;"> function init()
</span><span style="color: #008080;">302</span> <span style="color: #000000;"> {
</span><span style="color: #008080;">303</span> $<span style="color: #0000ff;">this</span>->state =<span style="color: #000000;"> self::STATE_INIT;
</span><span style="color: #008080;">304</span> $<span style="color: #0000ff;">this</span>-><span style="color: #000000;">bootstrap();
</span><span style="color: #008080;">305</span> <span style="color: #000000;"> }
</span><span style="color: #008080;">306</span>
<span style="color: #008080;">307</span> <span style="color: #008000;">/*</span><span style="color: #008000;">*
</span><span style="color: #008080;">308</span> <span style="color: #008000;"> * Initializes extensions and executes bootstrap components.初始化扩展并执行初始化程序组件
</span><span style="color: #008080;">309</span> <span style="color: #008000;"> * This method is called by [[init()]] after the application has been fully configured.
</span><span style="color: #008080;">310</span> <span style="color: #008000;"> * 该方法在应用完全配置后被[[init()]]调用
</span><span style="color: #008080;">311</span> <span style="color: #008000;"> * If you override this method, make sure you also call the parent implementation.
</span><span style="color: #008080;">312</span> <span style="color: #008000;">*/</span>
<span style="color: #008080;">313</span> <span style="color: #0000ff;">protected</span><span style="color: #000000;"> function bootstrap()
</span><span style="color: #008080;">314</span> <span style="color: #000000;"> {
</span><span style="color: #008080;">315</span> <span style="color: #0000ff;">if</span> ($<span style="color: #0000ff;">this</span>->extensions === <span style="color: #0000ff;">null</span>) {<span style="color: #008000;">//</span><span style="color: #008000;">如果没有配置，则调用Yii的默认扩展组件</span>
<span style="color: #008080;">316</span> $file = Yii::getAlias(<span style="color: #800000;">'</span><span style="color: #800000;">@vendor/yiisoft/extensions.php</span><span style="color: #800000;">'</span><span style="color: #000000;">);
</span><span style="color: #008080;">317</span> $<span style="color: #0000ff;">this</span>->extensions = is_file($file) ?<span style="color: #000000;"> include($file) : [];
</span><span style="color: #008080;">318</span> <span style="color: #000000;"> }
</span><span style="color: #008080;">319</span> <span style="color: #0000ff;">foreach</span> ($<span style="color: #0000ff;">this</span>->extensions <span style="color: #0000ff;">as</span><span style="color: #000000;"> $extension) {
</span><span style="color: #008080;">320</span> <span style="color: #0000ff;">if</span> (!empty($extension[<span style="color: #800000;">'</span><span style="color: #800000;">alias</span><span style="color: #800000;">'</span>])) {<span style="color: #008000;">//</span><span style="color: #008000;">如果扩展组件有设置别名</span>
<span style="color: #008080;">321</span> <span style="color: #0000ff;">foreach</span> ($extension[<span style="color: #800000;">'</span><span style="color: #800000;">alias</span><span style="color: #800000;">'</span>] <span style="color: #0000ff;">as</span> $name =><span style="color: #000000;"> $path) {
</span><span style="color: #008080;">322</span> Yii::setAlias($name, $path);<span style="color: #008000;">//</span><span style="color: #008000;">将给扩展的别名注册到别名数组中</span>
<span style="color: #008080;">323</span> <span style="color: #000000;"> }
</span><span style="color: #008080;">324</span> <span style="color: #000000;"> }
</span><span style="color: #008080;">325</span> <span style="color: #0000ff;">if</span> (isset($extension[<span style="color: #800000;">'</span><span style="color: #800000;">bootstrap</span><span style="color: #800000;">'</span>])) {<span style="color: #008000;">//</span><span style="color: #008000;">如果扩展组件有[[bootstrap]]配置 则初始化给扩展组件</span>
<span style="color: #008080;">326</span> $component = Yii::createObject($extension[<span style="color: #800000;">'</span><span style="color: #800000;">bootstrap</span><span style="color: #800000;">'</span><span style="color: #000000;">]);
</span><span style="color: #008080;">327</span> <span style="color: #0000ff;">if</span><span style="color: #000000;"> ($component instanceof BootstrapInterface) {
</span><span style="color: #008080;">328</span> Yii::trace(<span style="color: #800000;">"</span><span style="color: #800000;">Bootstrap with </span><span style="color: #800000;">"</span> . get_class($component) . <span style="color: #800000;">'</span><span style="color: #800000;">::bootstrap()</span><span style="color: #800000;">'</span><span style="color: #000000;">, __METHOD__);
</span><span style="color: #008080;">329</span> $component->bootstrap($<span style="color: #0000ff;">this</span><span style="color: #000000;">);
</span><span style="color: #008080;">330</span> } <span style="color: #0000ff;">else</span><span style="color: #000000;"> {
</span><span style="color: #008080;">331</span> Yii::trace(<span style="color: #800000;">"</span><span style="color: #800000;">Bootstrap with </span><span style="color: #800000;">"</span><span style="color: #000000;"> . get_class($component), __METHOD__);
</span><span style="color: #008080;">332</span> <span style="color: #000000;"> }
</span><span style="color: #008080;">333</span> <span style="color: #000000;"> }
</span><span style="color: #008080;">334</span> <span style="color: #000000;"> }
</span><span style="color: #008080;">335</span>
<span style="color: #008080;">336</span> <span style="color: #0000ff;">foreach</span> ($<span style="color: #0000ff;">this</span>->bootstrap <span style="color: #0000ff;">as</span> $<span style="color: #0000ff;">class</span><span style="color: #000000;">) {
</span><span style="color: #008080;">337</span> $component = <span style="color: #0000ff;">null</span><span style="color: #000000;">;
</span><span style="color: #008080;">338</span> <span style="color: #0000ff;">if</span> (is_string($<span style="color: #0000ff;">class</span><span style="color: #000000;">)) {
</span><span style="color: #008080;">339</span> <span style="color: #0000ff;">if</span> ($<span style="color: #0000ff;">this</span>->has($<span style="color: #0000ff;">class</span><span style="color: #000000;">)) {
</span><span style="color: #008080;">340</span> $component = $<span style="color: #0000ff;">this</span>-><span style="color: #0000ff;">get</span>($<span style="color: #0000ff;">class</span><span style="color: #000000;">);
</span><span style="color: #008080;">341</span> } elseif ($<span style="color: #0000ff;">this</span>->hasModule($<span style="color: #0000ff;">class</span><span style="color: #000000;">)) {
</span><span style="color: #008080;">342</span> $component = $<span style="color: #0000ff;">this</span>->getModule($<span style="color: #0000ff;">class</span><span style="color: #000000;">);
</span><span style="color: #008080;">343</span> } elseif (strpos($<span style="color: #0000ff;">class</span>, <span style="color: #800000;">'</span><span style="color: #800000;">\</span><span style="color: #800000;">'</span>) === <span style="color: #0000ff;">false</span><span style="color: #000000;">) {
</span><span style="color: #008080;">344</span> <span style="color: #0000ff;">throw</span> <span style="color: #0000ff;">new</span> InvalidConfigException(<span style="color: #800000;">"</span><span style="color: #800000;">Unknown bootstrapping component ID: $class</span><span style="color: #800000;">"</span><span style="color: #000000;">);
</span><span style="color: #008080;">345</span> <span style="color: #000000;"> }
</span><span style="color: #008080;">346</span> <span style="color: #000000;"> }
</span><span style="color: #008080;">347</span> <span style="color: #0000ff;">if</span> (!isset($component)) {<span style="color: #008000;">//</span><span style="color: #008000;">如果不存在，则调用Yii创建对象</span>
<span style="color: #008080;">348</span> $component = Yii::createObject($<span style="color: #0000ff;">class</span><span style="color: #000000;">);
</span><span style="color: #008080;">349</span> <span style="color: #000000;"> }
</span><span style="color: #008080;">350</span>
<span style="color: #008080;">351</span> <span style="color: #0000ff;">if</span><span style="color: #000000;"> ($component instanceof BootstrapInterface) {
</span><span style="color: #008080;">352</span> Yii::trace(<span style="color: #800000;">"</span><span style="color: #800000;">Bootstrap with </span><span style="color: #800000;">"</span> . get_class($component) . <span style="color: #800000;">'</span><span style="color: #800000;">::bootstrap()</span><span style="color: #800000;">'</span><span style="color: #000000;">, __METHOD__);
</span><span style="color: #008080;">353</span> $component->bootstrap($<span style="color: #0000ff;">this</span><span style="color: #000000;">);
</span><span style="color: #008080;">354</span> } <span style="color: #0000ff;">else</span><span style="color: #000000;"> {
</span><span style="color: #008080;">355</span> Yii::trace(<span style="color: #800000;">"</span><span style="color: #800000;">Bootstrap with </span><span style="color: #800000;">"</span><span style="color: #000000;"> . get_class($component), __METHOD__);
</span><span style="color: #008080;">356</span> <span style="color: #000000;"> }
</span><span style="color: #008080;">357</span> <span style="color: #000000;"> }
</span><span style="color: #008080;">358</span> }
未完待续。
PHP 网络编程技术与实例(曹衍龙)
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PHP网络编程技术详解由浅入深，全面、系统地介绍了PHP开发技术，并提供了大量实例，供读者实战演练。另外，笔者专门为本书录制了相应的配套教学视频，以帮助读者更好地学习本书内容。这些视频和书中的实例源代码一起收录于配书光盘中。本书共分4篇。第1篇是PHP准备篇，介绍了PHP的优势、开发环境及安装；第2篇是PHP基础篇，介绍了PHP中的常量与变量、运算符与表达式、流程控制以及函数；第3篇是进阶篇，介绍
