Laravel的$this->app以及app()是怎麼來的

斷點調試尋找對應文件，忽略次要步驟，僅描述核心動作，‘/’表示index.php所在目錄
地址:index.php

$app = require_once __DIR__.'/../bootstrap/app.php';

$app初始化
路徑/…/bootstrap/app.php

$app = new Illuminate\Foundation\Application(
    realpath(__DIR__.'/../')
);//$app初始化工作

$app初始化的類及構造函數

class Application extends Container implements ApplicationContract,HttpKernelInterface
{
    //繼承Container類，Container類實現應用契約接口與請求接口
    public function __construct($basePath = null){
       if ($basePath) {//$basePath = '/../'
           $this->setBasePath($basePath);//路徑綁定
       }

       $this->registerBaseBindings();//基礎綁定

       $this->registerBaseServiceProviders();//註冊基礎服務提供者

       $this->registerCoreContainerAliases();//註冊別名
    }
}

路徑綁定

Application的setBasePath(’/…/’)方法調用Container的instance(a b s t r a c t , abstract,abstract,instance)方法賦值Contaienr類instances
instances: array:9 [▼
“path” => “\var\www\app”
“path.base” => “\var\www”
“path.lang” => “\var\www\resources\lang”
“path.config” => “\var\www\config”
“path.public” => “\var\www\public”
“path.storage” => “\var\www\storage”
“path.database” => “\var\www\database”
“path.resources” => “\var\www\resources”
“path.bootstrap” => “\var\www\bootstrap”
]

基礎綁定

  向Container的instances中添加綁定
      "app" => Application {#2}
      "Illuminate\Container\Container" => Application {#2}
      "Illuminate\Foundation\PackageManifest" => PackageManifest {#4 ▼
            +files: Filesystem {#5}
            +basePath: "\var\www"
            +vendorPath: "\var\www\vendor"
            +manifestPath: "\var\www\bootstrap\cache\packages.php"
            +manifest: null
        }

    app與Container指向當前實例
    PackageMainfest 爲包管理實例，構造方法中files註冊文件系統實例

註冊基礎服務提供者

//class Application
protected function registerBaseServiceProviders()
{
    $this->register(new EventServiceProvider($this));

    $this->register(new LogServiceProvider($this));

    $this->register(new RoutingServiceProvider($this));
}

Event、Log、Routing基礎服務繼承ServiceProvider，初始化的時候將app屬性賦值Application實例

//class ServiceProvider    
public function __construct($app)
{
    $this->app = $app;
}

執行Application類register方法

//Application
public function register($provider, $options = [], $force = false)
{
    if (is_string($provider)) {
        $provider = $this->resolveProvider($provider);
    }

    if (method_exists($provider, 'register')) {
        $provider->register();//賦值bindings
    }
    //將服務提供者添加到serviceProviders屬性隊列
    //將服務提供者類名添加到loaderProviders屬性
    $this->markAsRegistered($provider);

    return $provider;
}

爲provider註冊提供了兩種方法；
一種是字符串類名直接實例，
一種是執行$$provider->register()方法註冊，
當前執行第二種方法，
回看當前EventServiceProvider實例的register方法

public function register()
{
    $this->app->singleton('events', function ($app) {
        return (new Dispatcher($app))->setQueueResolver(function () use ($app) {
            return $app->make(QueueFactoryContract::class);
        });
    });
}

調用Application實例的singleton方法

//class Continer
public function singleton($abstract, $concrete = null)
{
    $this->bind($abstract, $concrete, true);
}

調用bind方法，賦值bindings

//class Container
public function bind($abstract, $concrete = null, $shared = false)
{
    if (is_null($concrete)) {
        $concrete = $abstract;
    }

    if (! $concrete instanceof Closure) {
        $concrete = $this->getClosure($abstract, $concrete);
    }

    $this->bindings[$abstract] = compact('concrete', 'shared');

}

回到Application類register方法中並執行markAsRegistered($provider)

//class Application
protected function markAsRegistered($provider)
{
    $this->serviceProviders[] = $provider;

    $this->loadedProviders[get_class($provider)] = true;
}

LogServerProvider、RoutingServiceProvider與之類似

別名綁定

//class Application
public function registerCoreContainerAliases()
{
    foreach ([
        'app'                  => [self::class, \Illuminate\Contracts\Container\Container::class, \Illuminate\Contracts\Foundation\Application::class,  \Psr\Container\ContainerInterface::class],
        'auth'                 => [\Illuminate\Auth\AuthManager::class, \Illuminate\Contracts\Auth\Factory::class],
        'auth.driver'          => [\Illuminate\Contracts\Auth\Guard::class],
        'blade.compiler'       => [\Illuminate\View\Compilers\BladeCompiler::class],
        'cache'                => [\Illuminate\Cache\CacheManager::class, \Illuminate\Contracts\Cache\Factory::class],
        'cache.store'          => [\Illuminate\Cache\Repository::class, \Illuminate\Contracts\Cache\Repository::class],
        'config'               => [\Illuminate\Config\Repository::class, \Illuminate\Contracts\Config\Repository::class],
        'cookie'               => [\Illuminate\Cookie\CookieJar::class, \Illuminate\Contracts\Cookie\Factory::class, \Illuminate\Contracts\Cookie\QueueingFactory::class],
        'encrypter'            => [\Illuminate\Encryption\Encrypter::class, \Illuminate\Contracts\Encryption\Encrypter::class],
        'db'                   => [\Illuminate\Database\DatabaseManager::class],
        'db.connection'        => [\Illuminate\Database\Connection::class, \Illuminate\Database\ConnectionInterface::class],
        'events'               => [\Illuminate\Events\Dispatcher::class, \Illuminate\Contracts\Events\Dispatcher::class],
        'files'                => [\Illuminate\Filesystem\Filesystem::class],
        'filesystem'           => [\Illuminate\Filesystem\FilesystemManager::class, \Illuminate\Contracts\Filesystem\Factory::class],
        'filesystem.disk'      => [\Illuminate\Contracts\Filesystem\Filesystem::class],
        'filesystem.cloud'     => [\Illuminate\Contracts\Filesystem\Cloud::class],
        'hash'                 => [\Illuminate\Contracts\Hashing\Hasher::class],
        'translator'           => [\Illuminate\Translation\Translator::class, \Illuminate\Contracts\Translation\Translator::class],
        'log'                  => [\Illuminate\Log\Writer::class, \Illuminate\Contracts\Logging\Log::class, \Psr\Log\LoggerInterface::class],
        'mailer'               => [\Illuminate\Mail\Mailer::class, \Illuminate\Contracts\Mail\Mailer::class, \Illuminate\Contracts\Mail\MailQueue::class],
        'auth.password'        => [\Illuminate\Auth\Passwords\PasswordBrokerManager::class, \Illuminate\Contracts\Auth\PasswordBrokerFactory::class],
        'auth.password.broker' => [\Illuminate\Auth\Passwords\PasswordBroker::class, \Illuminate\Contracts\Auth\PasswordBroker::class],
        'queue'                => [\Illuminate\Queue\QueueManager::class, \Illuminate\Contracts\Queue\Factory::class, \Illuminate\Contracts\Queue\Monitor::class],
        'queue.connection'     => [\Illuminate\Contracts\Queue\Queue::class],
        'queue.failer'         => [\Illuminate\Queue\Failed\FailedJobProviderInterface::class],
        'redirect'             => [\Illuminate\Routing\Redirector::class],
        'redis'                => [\Illuminate\Redis\RedisManager::class, \Illuminate\Contracts\Redis\Factory::class],
        'request'              => [\Illuminate\Http\Request::class, \Symfony\Component\HttpFoundation\Request::class],
        'router'               => [\Illuminate\Routing\Router::class, \Illuminate\Contracts\Routing\Registrar::class, \Illuminate\Contracts\Routing\BindingRegistrar::class],
        'session'              => [\Illuminate\Session\SessionManager::class],
        'session.store'        => [\Illuminate\Session\Store::class, \Illuminate\Contracts\Session\Session::class],
        'url'                  => [\Illuminate\Routing\UrlGenerator::class, \Illuminate\Contracts\Routing\UrlGenerator::class],
        'validator'            => [\Illuminate\Validation\Factory::class, \Illuminate\Contracts\Validation\Factory::class],
        'view'                 => [\Illuminate\View\Factory::class, \Illuminate\Contracts\View\Factory::class],
    ] as $key => $aliases) {
        foreach ($aliases as $alias) {
            $this->alias($key, $alias);
        }
    }
}

爲alias屬性賦值

$app核心類綁定

/…/bootstrap/app.php

/**
 *核心類綁定
 */
$app->singleton(
    Illuminate\Contracts\Http\Kernel::class,
    App\Http\Kernel::class
);

$app->singleton(
    Illuminate\Contracts\Console\Kernel::class,
    App\Console\Kernel::class
);

$app->singleton(
    Illuminate\Contracts\Debug\ExceptionHandler::class,
    App\Exceptions\Handler::class
);

調用bind函數

//class Container
public function singleton($abstract, $concrete = null)
{
    $this->bind($abstract, $concrete, true);
}

對字符串類名進行默認回調函數綁定

//class Container
public function bind($abstract, $concrete = null, $shared = false)
{
    // If the factory is not a Closure, it means it is just a class name which is
    // bound into this container to the abstract type and we will just wrap it
    // up inside its own Closure to give us more convenience when extending.
    if (! $concrete instanceof Closure) {
        $concrete = $this->getClosure($abstract, $concrete);
    }
    $this->bindings[$abstract] = compact('concrete', 'shared');
}

getClosure返回默認回調函數

//class Container
protected function getClosure($abstract, $concrete)
{
    return function ($container, $parameters = []) use ($abstract, $concrete) {
        if ($abstract == $concrete) {
            return $container->build($concrete);
        }

        return $container->make($concrete, $parameters);
    };
}

最終：返回$app
/…/bootstrap/app.php

return $app;