了解 ServiceProvider 的加载

使用 Laravel 开始，我们总是绕不开 ServiceProvider 这个概念。在 Laravel 框架里到处充斥着 ServiceProvider —— AppServiceProvider、AuthServiceProvider、BroadcastServiceProvider、EventServiceProvider 和 RouteServiceProvider 等等。

还有我们在安装一些第三方插件时，都时不时有这么句话，将ServiceProvider 加入到 config/app.php 的 providers 数组中。

/*  
|--------------------------------------------------------------------------  
| Autoloaded Service Providers  
|--------------------------------------------------------------------------  
|  
| The service providers listed here will be automatically loaded on the  
| request to your application. Feel free to add your own services to  
| this array to grant expanded functionality to your applications.  
|  
*/  
  
'providers' => [  
  
    /*  
     * Laravel Framework Service Providers...     */    
    Illuminate\Auth\AuthServiceProvider::class,  
    Illuminate\Broadcasting\BroadcastServiceProvider::class,  
    Illuminate\Bus\BusServiceProvider::class,  
    Illuminate\Cache\CacheServiceProvider::class,  
    Illuminate\Foundation\Providers\ConsoleSupportServiceProvider::class,  
    Illuminate\Cookie\CookieServiceProvider::class,  
    Illuminate\Database\DatabaseServiceProvider::class,  
    Illuminate\Encryption\EncryptionServiceProvider::class,  
    Illuminate\Filesystem\FilesystemServiceProvider::class,  
    Illuminate\Foundation\Providers\FoundationServiceProvider::class,  
    Illuminate\Hashing\HashServiceProvider::class,  
    Illuminate\Mail\MailServiceProvider::class,  
    Illuminate\Notifications\NotificationServiceProvider::class,  
    Illuminate\Pagination\PaginationServiceProvider::class,  
    Illuminate\Pipeline\PipelineServiceProvider::class,  
    Illuminate\Queue\QueueServiceProvider::class,  
    Illuminate\Redis\RedisServiceProvider::class,  
    Illuminate\Auth\Passwords\PasswordResetServiceProvider::class,  
    Illuminate\Session\SessionServiceProvider::class,  
    Illuminate\Translation\TranslationServiceProvider::class,  
    Illuminate\Validation\ValidationServiceProvider::class,  
    Illuminate\View\ViewServiceProvider::class,  
  
    /*  
     * Package Service Providers...     */  
    /*     * Application Service Providers...     */  
    App\Providers\AppServiceProvider::class,  
    App\Providers\AuthServiceProvider::class,  
    // App\Providers\BroadcastServiceProvider::class,  
    App\Providers\EventServiceProvider::class,  
    App\Providers\RouteServiceProvider::class,  
    Coding01\GptAPI\GptServiceProvider::class,  
  
],

难道咱们就不想知道 Laravel 是如何加载这些 ServiceProviders 的吗？

所以今天从源代码的运行来看看是怎么实现加载的？

`Kernel`

我们简单过了一遍 new Application，我们回到 index.php 继续往下看：

$kernel = $app->make(Kernel::class);  
  
$response = $kernel->handle(  
    $request = Request::capture()  
)->send();  
  
$kernel->terminate($request, $response);

这个 $kernel 就是 Laravel 的「核」，而 $kernel->handle() 方法就是 Laravel 的「核中之核」了 —— 即，根据输入的 Request，输出 response。完成请求到响应的过程。

我们进入 $kernel->handle() 方法。

/**  
 * Handle an incoming HTTP request. 
 * 
 * @param  \Illuminate\Http\Request  $request  
 * @return \Illuminate\Http\Response  
 */  
public function handle($request)  
{  
    $this->requestStartedAt = Carbon::now();  
  
    try {  
        $request->enableHttpMethodParameterOverride();  
  
        $response = $this->sendRequestThroughRouter($request);  
    } catch (Throwable $e) {  
        $this->reportException($e);  
  
        $response = $this->renderException($request, $e);  
    }  
  
    $this->app['events']->dispatch(  
        new RequestHandled($request, $response)  
    );  
  
    return $response;  
}

排除其它「干扰」东西，眼睛关注到这行代码：

$response = $this->sendRequestThroughRouter($request);

这也暴露了，网络请求的三要素：request、router 和 response。

/**  
 * Send the given request through the middleware / router. 
 * 
 * @param  \Illuminate\Http\Request  $request  
 * @return \Illuminate\Http\Response  
 */  
protected function sendRequestThroughRouter($request)  
{  
    $this->app->instance('request', $request);  
  
    Facade::clearResolvedInstance('request');  
  
    $this->bootstrap();  
  
    return (new Pipeline($this->app))  
                ->send($request)  
                ->through($this->app->shouldSkipMiddleware() ? [] : $this->middleware)  
                ->then($this->dispatchToRouter());  
}

但今天我们说的不是考虑执行的问题，我们需要知道什么时候加载我们的 ServiceProviders 所以在 return 执行之前的代码 ($this->bootstrap();) 就是初始化 ServiceProviders等信息的过程

/**  
 * Bootstrap the application for HTTP requests. 
 * 
 * @return void  
 */  
public function bootstrap()  
{  
    if (! $this->app->hasBeenBootstrapped()) {  
        $this->app->bootstrapWith($this->bootstrappers());  
    }  
}

// Application

/**  
 * Run the given array of bootstrap classes. 
 * 
 * @param  string[]  $bootstrappers  
 * @return void  
 */  
public function bootstrapWith(array $bootstrappers)  
{  
    $this->hasBeenBootstrapped = true;  
  
    foreach ($bootstrappers as $bootstrapper) {  
        $this['events']->dispatch('bootstrapping: '.$bootstrapper, [$this]);  
  
        $this->make($bootstrapper)->bootstrap($this);  
  
        $this['events']->dispatch('bootstrapped: '.$bootstrapper, [$this]);  
    }  
}

到此我们知道，实际上遍历执行 $bootstrappers->bootstrap($this)

此时我们看看 $bootstrappers：

/**  
 * The bootstrap classes for the application. 
 * 
 * @var string[]  
 */  
protected $bootstrappers = [  
    \Illuminate\Foundation\Bootstrap\LoadEnvironmentVariables::class,  
    \Illuminate\Foundation\Bootstrap\LoadConfiguration::class,  
    \Illuminate\Foundation\Bootstrap\HandleExceptions::class,  
    \Illuminate\Foundation\Bootstrap\RegisterFacades::class,  
    \Illuminate\Foundation\Bootstrap\RegisterProviders::class,  
    \Illuminate\Foundation\Bootstrap\BootProviders::class,  
];

这六个类的作用主要是：加载环境变量、config、异常处理、注册 facades、和最后我们关注的 ServiceProvider 的 register和 boot。

我们分别来看看。

`RegisterProviders`

class RegisterProviders  
{  
    /**  
     * Bootstrap the given application.     
     *     
     * @param  \Illuminate\Contracts\Foundation\Application  $app  
     * @return void  
     */  
    public function bootstrap(Application $app)  
    {  
        $app->registerConfiguredProviders();  
    }  
}

实际上是调用 Application 的 registerConfiguredProviders()：

/**  
 * Register all of the configured providers.
 * 
 * @return void  
 */  
public function registerConfiguredProviders()  
{  
    $providers = Collection::make($this->make('config')->get('app.providers'))  
                    ->partition(fn ($provider) => str_starts_with($provider, 'Illuminate\\'));  
  
    $providers->splice(1, 0, [$this->make(PackageManifest::class)->providers()]);  
  
    (new ProviderRepository($this, new Filesystem, $this->getCachedServicesPath()))  
                ->load($providers->collapse()->toArray());  
}

这个就厉害了。加载所有已配置的 ServiceProvider，主要包含了在配置文件 config/app.php 里的 providers，上文讲述的第三方所有满足的 ServiceProviders，以及在 boostrap/cached/service.php 中的所有 Providers。

最后执行 ProviderRepository::load 方法，进行遍历 register：

/**  
 * Register the application service providers. 
 * 
 * @param  array  $providers  
 * @return void  
 */  
public function load(array $providers)  
{  
    $manifest = $this->loadManifest();  
  
    // First we will load the service manifest, which contains information on all  
    // service providers registered with the application and which services it    
    // provides. This is used to know which services are "deferred" loaders.    
    
    if ($this->shouldRecompile($manifest, $providers)) {  
        $manifest = $this->compileManifest($providers);  
    }  
  
    // Next, we will register events to load the providers for each of the events  
    // that it has requested. This allows the service provider to defer itself    
    // while still getting automatically loaded when a certain event occurs.    
    foreach ($manifest['when'] as $provider => $events) {  
        $this->registerLoadEvents($provider, $events);  
    }  
  
    // We will go ahead and register all of the eagerly loaded providers with the  
    // application so their services can be registered with the application as    
    // a provided service. Then we will set the deferred service list on it.    
    foreach ($manifest['eager'] as $provider) {  
        $this->app->register($provider);  
    }  
  
    $this->app->addDeferredServices($manifest['deferred']);  
}

`BootProviders`

class BootProviders  
{  
    /**  
     * Bootstrap the given application.     
     *     
     * @param  \Illuminate\Contracts\Foundation\Application  $app  
     * @return void  
     */  
    public function bootstrap(Application $app)  
    {  
        $app->boot();  
    }  
}

我们按图索骥：

/**  
 * Boot the application's service providers. 
 * 
 * @return void  
 */  
public function boot()  
{  
    if ($this->isBooted()) {  
        return;  
    }  
  
    // Once the application has booted we will also fire some "booted" callbacks  
    // for any listeners that need to do work after this initial booting gets    
    // finished. This is useful when ordering the boot-up processes we run.    
    $this->fireAppCallbacks($this->bootingCallbacks);  
  
    array_walk($this->serviceProviders, function ($p) {  
        $this->bootProvider($p);  
    });  
  
    $this->booted = true;  
  
    $this->fireAppCallbacks($this->bootedCallbacks);  
}

...

/**  
 * Boot the given service provider. 
 * 
 * @param  \Illuminate\Support\ServiceProvider  $provider 
 * @return void
 */
protected function bootProvider(ServiceProvider $provider)  
{  
    $provider->callBootingCallbacks();  
  
    if (method_exists($provider, 'boot')) {  
        $this->call([$provider, 'boot']);  
    }  
  
    $provider->callBootedCallbacks();  
}

也就是说遍历执行所有 ServiceProviders 的 boot() (前提是该 ServiceProvider 有定义该方法)。

通过分析 index.php 执行过程，发现 Application 主要是发现各种 ServiceProviders，而 $kernel 更多的是在处理 Request请求之前，把所有的 ServiceProvider进行注册 (register)，然后再 boot。把所有的 ServiceProviders装载进系统内存中，供处理各式各样的 Request 使用。

而每一个 ServiceProvider 各司其职，负责各自不同的职能，来满足 Laravel 系统的各种需要。

下文我们将重点说说这些 ServiceProvider 的含义和作用。敬请期待！

未完待续

看 Application 类

`registerBaseBindings()`

`registerBaseServiceProviders()`

`Kernel`

`RegisterProviders`

`BootProviders`

总结

如果觉得文章内容对您有用打赏

看 Application 类

registerBaseBindings()

registerBaseServiceProviders()

Kernel

RegisterProviders

BootProviders

总结

如果觉得文章内容对您有用 打赏

`registerBaseBindings()`

`registerBaseServiceProviders()`

`Kernel`

`RegisterProviders`

`BootProviders`

如果觉得文章内容对您有用打赏