【Laravel5源码阅读】数据库服务提供者DatabaseServiceProvider

<?php

namespace Illuminate\Database;

use Faker\Factory as FakerFactory;
use Faker\Generator as FakerGenerator;
use Illuminate\Database\Eloquent\Model;
use Illuminate\Support\ServiceProvider;
use Illuminate\Database\Eloquent\QueueEntityResolver;
use Illuminate\Database\Connectors\ConnectionFactory;
use Illuminate\Database\Eloquent\Factory as EloquentFactory;

class DatabaseServiceProvider extends ServiceProvider
{
    /**
     * Bootstrap the application events.
     * 启动应用程序事件。
     * @return void
     */
    public function boot()
    {
        Model::setConnectionResolver($this->app['db']);

        Model::setEventDispatcher($this->app['events']);
    }

    /**
     * Register the service provider.
     * 注册服务提供者
     * @return void
     */
    public function register()
    {
        Model::clearBootedModels();

        $this->registerEloquentFactory();

        $this->registerQueueableEntityResolver();

        // 连接工厂用于在数据库上创建实际的连接实例。 我们会将工厂注入管理器，以便它可以在实际需要而不是之前建立连接。
        $this->app->singleton('db.factory', function ($app) {
            return new ConnectionFactory($app);
        });

        // 数据库管理器用于解析各种连接，因为可能管理多个连接。 它还实现了连接解析器接口，其他需要连接的组件可以使用该接口。
        $this->app->singleton('db', function ($app) {
            return new DatabaseManager($app, $app['db.factory']);
        });

        $this->app->bind('db.connection', function ($app) {
            return $app['db']->connection();
        });
    }

    /**
     * Register the Eloquent factory instance in the container.
     * 在容器中注册 Eloquent 工厂实例。
     * @return void
     */
    protected function registerEloquentFactory()
    {
        $this->app->singleton(FakerGenerator::class, function () {
            return FakerFactory::create();
        });

        $this->app->singleton(EloquentFactory::class, function ($app) {
            $faker = $app->make(FakerGenerator::class);

            return EloquentFactory::construct($faker, database_path('factories'));
        });
    }

    /**
     * Register the queueable entity resolver implementation.
     * 注册可排队实体解析器实现。
     * @return void
     */
    protected function registerQueueableEntityResolver()
    {
        $this->app->singleton('Illuminate\Contracts\Queue\EntityResolver', function () {
            return new QueueEntityResolver;
        });
    }
}