yii2源码学习笔记(九）

Application是所有应用程序类的基类，接下来了解一下它的源码。yii2\base\Application.php。

<?php
/**
 * @link http://www.yiiframework.com/
 * @copyright Copyright (c) 2008 Yii Software LLC
 * @license http://www.yiiframework.com/license/
 */

namespace yii\base;

use Yii;

/**
 * Application is the base class for all application classes.
 * 是所有应用程序类的基类
 * @property \yii\web\AssetManager $assetManager The asset manager application component. This property is
 * read-only.资产管理器应用组件，只读
 * @property \yii\rbac\ManagerInterface $authManager The auth manager application component. Null is returned
 * 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
 * @property string $basePath The root directory of the application. 应用程序的根目录。
 * @property \yii\caching\Cache $cache The cache application component. Null if the component is not enabled.
 * This property is read-only.缓存应用程序组件。
 * @property \yii\db\Connection $db The database connection. This property is read-only.数据库连接。
 * @property \yii\web\ErrorHandler|\yii\console\ErrorHandler $errorHandler The error handler application
 * component. This property is read-only.错误处理程序应用程序组件
 * @property \yii\i18n\Formatter $formatter The formatter application component. This property is read-only.
 * 格式化程序的应用程序组件。
 * @property \yii\i18n\I18N $i18n The internationalization application component. This property is read-only.
 * 国际化应用组件。
 * @property \yii\log\Dispatcher $log The log dispatcher application component. This property is read-only.
 * 日志调度程序组件。
 * @property \yii\mail\MailerInterface $mailer The mailer application component. This property is read-only.
 * 邮件应用程序组件。
 * @property \yii\web\Request|\yii\console\Request $request The request component. This property is read-only.
 * 请求组件。
 * @property \yii\web\Response|\yii\console\Response $response The response component. This property is
 * read-only.反应元件。
 * @property string $runtimePath The directory that stores runtime files. Defaults to the "runtime"
 * subdirectory under [[basePath]].存储运行时文件的目录。
 * @property \yii\base\Security $security The security application component. This property is read-only.
 * 安全应用组件。
 * @property string $timeZone The time zone used by this application.该应用程序使用的时区。
 * @property string $uniqueId The unique ID of the module. This property is read-only.模块的唯一标识。
 * @property \yii\web\UrlManager $urlManager The URL manager for this application. This property is read-only.
 * 此应用程序的网址管理器。
 * @property string $vendorPath The directory that stores vendor files. Defaults to "vendor" directory under
 * [[basePath]].存储供应商文件的目录。
 * @property View|\yii\web\View $view The view application component that is used to render various view
 * 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
 *
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @since 2.0
 */
abstract class Application extends Module
{
    /**
     * @event Event an event raised before the application starts to handle a request.
     * 在应用程序开始处理请求之前提出的事件。
     */
    const EVENT_BEFORE_REQUEST = 'beforeRequest';
    /**
     * @event Event an event raised after the application successfully handles a request (before the response is sent out).
     * 该应用程序成功处理请求后提出的事件
     */
    const EVENT_AFTER_REQUEST = 'afterRequest';
    /**
     * Application state used by [[state]]: application just started.
     * [[state]]适用状态：刚开始应用
     */
    const STATE_BEGIN = 0;
    /**
     * Application state used by [[state]]: application is initializing.
     *  [[state]]应用程序状态：应用程序初始化。
     */
    const STATE_INIT = 1;
    /**
     * Application state used by [[state]]: application is triggering [[EVENT_BEFORE_REQUEST]].
     *  [[state]]应用程序状态：应用触发[[EVENT_BEFORE_REQUEST]]
     */
    const STATE_BEFORE_REQUEST = 2;
    /**
     * Application state used by [[state]]: application is handling the request.
     *  [[state]]应用程序状态：应用程序处理请求。
     */
    const STATE_HANDLING_REQUEST = 3;
    /**
     * Application state used by [[state]]: application is triggering [[EVENT_AFTER_REQUEST]]..
     *  [[state]]应用程序状态：应用触发[[EVENT_AFTER_REQUEST]]
     */
    const STATE_AFTER_REQUEST = 4;
    /**
     * Application state used by [[state]]: application is about to send response.
     *  [[state]]应用程序状态：应用程序即将发送响应。
     */
    const STATE_SENDING_RESPONSE = 5;
    /**
     * Application state used by [[state]]: application has ended.
     *  [[state]]应用程序状态：应用程序结束。
     */
    const STATE_END = 6;

    /**
     * @var string the namespace that controller classes are located in.控制器类的命名空间位置。
     * This namespace will be used to load controller classes by prepending it to the controller class name.
     * The default namespace is `app\controllers`.
     * 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`app\controllers`。
     * Please refer to the [guide about class autoloading](guide:concept-autoloading.md) for more details.
     */
    public $controllerNamespace = 'app\\controllers';
    /**
     * @var string the application name.应用程序名称。
     */
    public $name = 'My Application';
    /**
     * @var string the version of this application.此应用程序的版本。
     */
    public $version = '1.0';
    /**
     * @var string the charset currently used for the application.目前使用的字符集。
     */
    public $charset = 'UTF-8';
    /**
     * @var string the language that is meant to be used for end users. It is recommended that you
     * use [IETF language tags](http://en.wikipedia.org/wiki/IETF_language_tag). For example, `en` stands
     * for English, while `en-US` stands for English (United States).
     * 用来作为终端用户使用的语言
     * @see sourceLanguage
     */
    public $language = 'en-US';
    /**
     * @var string the language that the application is written in. This mainly refers to
     * the language that the messages and view files are written in.
     * 应用程序编写的语言。
     * @see language
     */
    public $sourceLanguage = 'en-US';
    /**
     * @var Controller the currently active controller instance当前活动控制器实例
     */
    public $controller;
    /**
     * @var string|boolean the layout that should be applied for views in this application. Defaults to 'main'.
     * If this is false, layout will be disabled.
     * 该应用程序中应用的布局。
     */
    public $layout = 'main';
    /**
     * @var string the requested route请求的路径    请求的路径
     */
    public $requestedRoute;
    /**
     * @var Action the requested Action. If null, it means the request cannot be resolved into an action.
     * 操作所要求的行动
     */
    public $requestedAction;
    /**
     * @var array the parameters supplied to the requested action.
     * 所请求的动作提供的参数。
     */
    public $requestedParams;
    /**
     * @var array list of installed Yii extensions. Each array element represents a single extension
     * with the following structure:
     * 安装Yii扩展名列表。每个数组元素代表一个扩展
     *
     * ~~~
     * [
     *     'name' => 'extension name',
     *     'version' => 'version number',
     *     'bootstrap' => 'BootstrapClassName',  // optional, may also be a configuration array
     *     'alias' => [
     *         '@alias1' => 'to/path1',
     *         '@alias2' => 'to/path2',
     *     ],
     * ]
     * ~~~
     *
     * The "bootstrap" class listed above will be instantiated during the application
     * [[bootstrap()|bootstrapping process]]. If the class implements [[BootstrapInterface]],
     * its [[BootstrapInterface::bootstrap()|bootstrap()]] method will be also be called.
     *
     * If not set explicitly in the application config, this property will be populated with the contents of
     * 如果在应用程序配置中没有设置，该属性将填充到内容
     * @vendor/yiisoft/extensions.php`.
     */
    public $extensions;
    /**
     * @var array list of components that should be run during the application [[bootstrap()|bootstrapping process]].
     * 组件的列表，运行在 [[bootstrap()|bootstrapping process]]中的应用
     * Each component may be specified in one of the following formats:
     *
     * - an application component ID as specified via [[components]].
     * - a module ID as specified via [[modules]].
     * - a class name.
     * - a configuration array.
     *
     * During the bootstrapping process, each component will be instantiated. If the component class
     * implements [[BootstrapInterface]], its [[BootstrapInterface::bootstrap()|bootstrap()]] method
     * will be also be called.
     * 在整个启动过程中，每个组件被实例化。如果组件类提到 [[BootstrapInterface]]， 
     * [[BootstrapInterface::bootstrap()|bootstrap()]]方法也会调用
     */
    public $bootstrap = [];
    /**
     * @var integer the current application state during a request handling life cycle.
     * This property is managed by the application. Do not modify this property.    
     * 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。
     */
    public $state;
    /**
     * @var array list of loaded modules indexed by their class names.
     * 加载模块列表由它们的类名称索引组成。
     */
    public $loadedModules = [];


    /**
     * Constructor.构造函数
     * @param array $config name-value pairs that will be used to initialize the object properties.
     * Note that the configuration must contain both [[id]] and [[basePath]].
     * 用来初始化对象属性的 name-value 注意配置必须包含[[id]] 和[[basePath]].
     * @throws InvalidConfigException if either [[id]] or [[basePath]] configuration is missing.
     * 如果是修改[[id]] 或[[basePath]] 则配置丢失。
     */
    public function __construct($config = [])
    {
        Yii::$app = $this;// 将自身的实例绑到Yii的$app上
        $this->setInstance($this);// 将自身加入到loadedModules中

        $this->state = self::STATE_BEGIN;// 设置状态为刚开始

        // 做预处理配置
        $this->preInit($config);

        $this->registerErrorHandler($config);

        Component::__construct($config);
    }

    /**
     * Pre-initializes the application. 初始化应用。
     * This method is called at the beginning of the application constructor.
     * It initializes several important application properties.
     * 在构造函数中调用该方法，用于初始化一些重要的属性
     * If you override this method, please make sure you call the parent implementation.
     * @param array $config the application configuration   应用的配置
     * @throws InvalidConfigException if either [[id]] or [[basePath]] configuration is missing.
     */
    public function preInit(&$config)
    {
         // 使用了&符号，表示$config的修改会保留
        if (!isset($config['id'])) {//判断配置中是否有application ID ，如果没有，抛出异常
            throw new InvalidConfigException('The "id" configuration for the Application is required.');
        }
        if (isset($config['basePath'])) {
            // 是否配置项目的root路径
            $this->setBasePath($config['basePath']);
             //赋值给模块的_basepath属性，并在设置后删除
            unset($config['basePath']);
        } else {//否则抛出异常
            throw new InvalidConfigException('The "basePath" configuration for the Application is required.');
        }
        //如果配置文件中设置了 vendorPath 使用配置的值，并在设置后删除，否则使用默认的
        if (isset($config['vendorPath'])) {
            $this->setVendorPath($config['vendorPath']);
            unset($config['vendorPath']);
        } else {
            // set "@vendor"
            $this->getVendorPath();
        }
        //如果配置文件中设置了 runtimePath 使用配置的值，并在设置后删除，否则使用默认的
        if (isset($config['runtimePath'])) {
            $this->setRuntimePath($config['runtimePath']);
            unset($config['runtimePath']);
        } else {
            // set "@runtime"
            $this->getRuntimePath();
        }
         //如果配置文件中设置了 timeZone 使用配置的值，并在设置后删除，否则使用默认的时区
        if (isset($config['timeZone'])) {
            $this->setTimeZone($config['timeZone']);
            unset($config['timeZone']);
        } elseif (!ini_get('date.timezone')) {
            $this->setTimeZone('UTC');
        }

        // merge core components with custom components
        foreach ($this->coreComponents() as $id => $component) {
            if (!isset($config['components'][$id])) {
                // 如果配置中没有配置相应的核心component，就赋给它
                $config['components'][$id] = $component;
            } elseif (is_array($config['components'][$id]) && !isset($config['components'][$id]['class'])) {
                 // 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
                $config['components'][$id]['class'] = $component['class'];
            }
        }
    }

    /**
     * @inheritdoc
     */
    public function init()
    {
        $this->state = self::STATE_INIT;
        $this->bootstrap();
    }

    /**
     * Initializes extensions and executes bootstrap components.初始化扩展并执行初始化程序组件
     * This method is called by [[init()]] after the application has been fully configured.
     * 该方法在应用完全配置后被[[init()]]调用
     * If you override this method, make sure you also call the parent implementation.
     */
    protected function bootstrap()
    {
        if ($this->extensions === null) {//如果没有配置，则调用Yii的默认扩展组件
            $file = Yii::getAlias('@vendor/yiisoft/extensions.php');
            $this->extensions = is_file($file) ? include($file) : [];
        }
        foreach ($this->extensions as $extension) {
            if (!empty($extension['alias'])) {//如果扩展组件有设置别名
                foreach ($extension['alias'] as $name => $path) {
                    Yii::setAlias($name, $path);//将给扩展的别名注册到别名数组中
                }
            }
            if (isset($extension['bootstrap'])) {//如果扩展组件有[[bootstrap]]配置 则初始化给扩展组件
                $component = Yii::createObject($extension['bootstrap']);
                if ($component instanceof BootstrapInterface) {
                    Yii::trace("Bootstrap with " . get_class($component) . '::bootstrap()', __METHOD__);
                    $component->bootstrap($this);
                } else {
                    Yii::trace("Bootstrap with " . get_class($component), __METHOD__);
                }
            }
        }

        foreach ($this->bootstrap as $class) {
            $component = null;
            if (is_string($class)) {
                if ($this->has($class)) {
                    $component = $this->get($class);
                } elseif ($this->hasModule($class)) {
                    $component = $this->getModule($class);
                } elseif (strpos($class, '\\') === false) {
                    throw new InvalidConfigException("Unknown bootstrapping component ID: $class");
                }
            }
            if (!isset($component)) {//如果不存在，则调用Yii创建对象
                $component = Yii::createObject($class);
            }

            if ($component instanceof BootstrapInterface) {
                Yii::trace("Bootstrap with " . get_class($component) . '::bootstrap()', __METHOD__);
                $component->bootstrap($this);
            } else {
                Yii::trace("Bootstrap with " . get_class($component), __METHOD__);
            }
        }
    }

未完待续。