Yii2中 Yii::$app $app这个变量是在哪里实例化的?
最常用的服务定位器是application(应用)对象,可以通过 \Yii::$app 访问
回复内容:
最常用的服务定位器是application(应用)对象,可以通过 \Yii::$app 访问
看下源码就知道了,如果你的应用是一个web应用,其index.php中(new yii\web\Application($config))->run();
调用Application的构造方法,而其继承自yii\base\Application
构造方法为
<code>public function __construct($config = []) { Yii::$app = $this; $this->setInstance($this); $this->state = self::STATE_BEGIN; $this->preInit($config); $this->registerErrorHandler($config); Component::__construct($config); } </code>
具体往后的实例化过程,你可以按照找个顺序继续查看源码。有什么问题可以留言,查看源码可以帮助你迅速理解yiiframework的初始化及运行过程
这是个神奇的变量!

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