yii2框架随笔23

今天继续阅读BaseYii.php

<?php
  /**
     * Class autoload loader.
     * 自动装载类加载程序。
     * This method is invoked automatically when PHP sees an unknown class.
     * PHP用该方法自动调用一个未知类。
     * The method will attempt to include the class file according to the following procedure:
     * 方法将根据下列程序尝试包括类文件:
     * 1. Search in [[classMap]];
     * 2. If the class is namespaced (e.g. `yiiaseComponent`), it will attempt
     *    to include the file associated with the corresponding path alias
     *    (e.g. `@yii/base/Component.php`);
     * 如果类名称空间(如。yiiaseComponent),它将尝试包括文件与相应的路径别名(如。“@yii/base/Component.php ');

     * Example: When aliases `@yii` and `@yii/bootstrap` are defined, classes in the `yiiootstrap` namespace
     * will be loaded using the `@yii/bootstrap` alias which points to the directory where bootstrap extension
     * files are installed and all classes from other `yii` namespaces will be loaded from the yii framework directory.
     * 例子:当别名“@yii”和“@yii /引导”定义,yii 引导的名称空间中的类将加载使用“@yii /引导”别名指向的目录引导扩展
     * 文件安装和所有其他类从“yii”名称空间将从yii加载框架目录。
     * Also the [guide section on autoloading](guide:concept-autoloading).
     *
     * @param string $className the fully qualified class name without a leading backslash ""
     * @throws UnknownClassException if the class does not exist in the class file
     */
    public static function autoload($className)
    {
        // 自动加载类
        if (isset(static::$classMap[$className])) {
            // 如果 $classMap 中存在该类，就直接使用
            $classFile = static::$classMap[$className];
            // 如果第一个字符串为'@'，就意味着对应的文件地址是别名，就将它转化成真实的文件地址
            if ($classFile[0] === '@') {
                $classFile = static::getAlias($classFile);
            }
        } elseif (strpos($className, '\') !== false) {
            // 如果存在'\',就意味着含有 namespace,可以拼成别名，再根据别名获取真实的文件地址
            $classFile = static::getAlias('@' . str_replace('\', '/', $className) . '.php', false);
            // 没取到真是文件地址或者获取的地址不是一个文件，就返回空
            if ($classFile === false || !is_file($classFile)) {
                return;
            }
        } else {
            return;
        }
        // 引入该类的文件
        include($classFile);
        // 如果是调试模式，而且 $className 即不是类，不是接口，也不是 trait，就抛出异常
        if (YII_DEBUG && !class_exists($className, false) && !interface_exists($className, false) && !trait_exists($className, false)) {
            throw new UnknownClassException("Unable to find '$className' in file: $classFile. Namespace missing?");
        }
    }
    /**
     * Creates a new object using the given configuration.
     * 使用给定的配置创建一个新的对象。
     * You may view this method as an enhanced version of the `new` operator.
     * 你可能会认为这种方法是一个增强版的“新”操作符。
     * The method supports creating an object based on a class name, a configuration array or
     * an anonymous function.
     * 该方法支持基于类名创建一个对象,数组或配置
     * 一个匿名函数。
     *
     * Below are some usage examples:
     * 以下是一些使用例子:
     *
     * ```php
     * // create an object using a class name
     * $object = Yii::createObject('yiidbConnection');
     *
     * // create an object using a configuration array
     * $object = Yii::createObject([
     *     'class' => 'yiidbConnection',
     *     'dsn' => 'mysql:host=127.0.0.1;dbname=demo',
     *     'username' => 'root',
     *     'password' => '',
     *     'charset' => 'utf8',
     * ]);
     *
     *
     * @param string|array|callable $type the object type. This can be specified in one of the following forms:
     * @param array $params the constructor parameters
     * @return object the created object
     * @throws InvalidConfigException if the configuration is invalid.
     * @see yiidiContainer
     */
    public static function createObject($type, array $params = [])
    {
        if (is_string($type)) {
            // 如果是一个字符串，就代表是类的名称，如：yiiwebErrorHandler
            return static::$container->get($type, $params);
        } elseif (is_array($type) && isset($type['class'])) {
            // 是个数组，其中的$type['class']代表类的名称
            $class = $type['class'];
            unset($type['class']);
            return static::$container->get($class, $params, $type);
        } elseif (is_callable($type, true)) {
            // 是个PHP callable，那就调用它，并将其返回值作为服务或组件的实例返回
            return call_user_func($type, $params);
        } elseif (is_array($type)) {
            throw new InvalidConfigException('Object configuration must be an array containing a "class" element.');
        } else {
            throw new InvalidConfigException("Unsupported configuration type: " . gettype($type));
        }
    }

        /**
     * Configures an object with the initial property values.
     *
     * 配置初始化一个Object，为该对象属性赋值
     *
     * @param object $object the object to be configured
     * @param array $properties the property initial values given in terms of name-value pairs.
     * @return object the object itself
     */
    public static function configure($object, $properties)
    {
        // 遍历配置里面的内容，一一赋值到相应的属性上
        foreach ($properties as $name => $value) {
            $object->$name = $value;
        }
        return $object;
    }