【Laravel-海贼王系列】第四章，Kernel 类解析

Love The Way You Lie 2022-03-14 13:34 195阅读 0赞

### 我们将进入 Kernel 的世界看看laravel是怎么启动的。 ###

#### 头部申明 ####

namespace App\Http;
    
    use Illuminate\Foundation\Http\Kernel as HttpKernel;
    
    class Kernel extends HttpKernel // 继承于Http内核
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#### 成员变量 ####

自身成员
        protected $middleware = [
            \App\Http\Middleware\CheckForMaintenanceMode::class,
            \Illuminate\Foundation\Http\Middleware\ValidatePostSize::class,
            \App\Http\Middleware\TrimStrings::class,
            \Illuminate\Foundation\Http\Middleware\ConvertEmptyStringsToNull::class,
            \App\Http\Middleware\TrustProxies::class,
        ]; // 应用全局中间件,运行于每一个请求
        
        protected $middlewareGroups = [
            'web' => [
                \App\Http\Middleware\EncryptCookies::class,
                \Illuminate\Cookie\Middleware\AddQueuedCookiesToResponse::class,
                \Illuminate\Session\Middleware\StartSession::class,
                // \Illuminate\Session\Middleware\AuthenticateSession::class,
                \Illuminate\View\Middleware\ShareErrorsFromSession::class,
                \App\Http\Middleware\VerifyCsrfToken::class,
                \Illuminate\Routing\Middleware\SubstituteBindings::class,
            ],
    
            'api' => [
                'throttle:60,1',
                'bindings',
            ],
        ]; // 应用路由中间件组
    
        protected $routeMiddleware = [
            'auth' => \App\Http\Middleware\Authenticate::class,
            'auth.basic' => \Illuminate\Auth\Middleware\AuthenticateWithBasicAuth::class,
            'bindings' => \Illuminate\Routing\Middleware\SubstituteBindings::class,
            'cache.headers' => \Illuminate\Http\Middleware\SetCacheHeaders::class,
            'can' => \Illuminate\Auth\Middleware\Authorize::class,
            'guest' => \App\Http\Middleware\RedirectIfAuthenticated::class,
            'signed' => \Illuminate\Routing\Middleware\ValidateSignature::class,
            'throttle' => \Illuminate\Routing\Middleware\ThrottleRequests::class,
            'verified' => \Illuminate\Auth\Middleware\EnsureEmailIsVerified::class,
        ];// 应用路由中间件,可以分配给组也可以单独
        
        protected $middlewarePriority = [
            \Illuminate\Session\Middleware\StartSession::class,
            \Illuminate\View\Middleware\ShareErrorsFromSession::class,
            \App\Http\Middleware\Authenticate::class,
            \Illuminate\Session\Middleware\AuthenticateSession::class,
            \Illuminate\Routing\Middleware\SubstituteBindings::class,
            \Illuminate\Auth\Middleware\Authorize::class,
        ];  // 强制非全局中间件始终按给定顺序。
    
      继承Http Kernel成员
        protected $app; // Application实例
        protected $router; // \Illuminate\Routing\Router 路由实例
        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,
        ]; // 应用需要引导的类
        
        protected $middleware = []; // 应用中间件堆栈
        
        protected $middlewareGroups = []; // 应用中间件组
        
        protected $routeMiddleware = []; // 路由中间件
        
        protected $middlewarePriority = [
            \Illuminate\Session\Middleware\StartSession::class,
            \Illuminate\View\Middleware\ShareErrorsFromSession::class,
            \Illuminate\Auth\Middleware\Authenticate::class,
            \Illuminate\Session\Middleware\AuthenticateSession::class,
            \Illuminate\Routing\Middleware\SubstituteBindings::class,
            \Illuminate\Auth\Middleware\Authorize::class,
        ]; // 强制非全局中间件始终按给定顺序。
        
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#### 构造函数(继承自http kernel) ####

public function __construct(Application $app, Router $router) 
        
        // 通过容器的build方法自动找出所有的依赖进行实例化传入。
        // 调用链是 $app->make()到$container->make(),$container->resolve(),$container->build()。
    
        {
            $this->app = $app;
            
             // 将实例化的路由对象赋值给成员
            $this->router = $router;
    
            // 将中间件强制顺序组传给路由
            $router->middlewarePriority = $this->middlewarePriority;
    
            foreach ($this->middlewareGroups as $key => $middleware) {
                $router->middlewareGroup($key, $middleware);
            } // 遍历所有中间件组传给路由的组对应
    
            foreach ($this->routeMiddleware as $key => $middleware) {
                $router->aliasMiddleware($key, $middleware);
            } // 遍历成员,将值赋值给路由别名
        }
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构造完成之后将获得一个包含路由和中间件的内核对象, 接着我们解析内核的重要方法。

#### 主要方法解析 ####

public function handle($request) // 接收一个 Illuminate\Http\Request 请求对象
        {
            try {
                // 启用http方法参数覆盖,可能导致CSRF攻击。
                $request->enableHttpMethodParameterOverride(); 
                
                // 下面解析这个方法
                $response = $this->sendRequestThroughRouter($request); 
            } catch (Exception $e) {
                $this->reportException($e);
    
                $response = $this->renderException($request, $e);
            } catch (Throwable $e) {
                $this->reportException($e = new FatalThrowableError($e));
    
                $response = $this->renderException($request, $e);
            } // 异常处理相关
    
            $this->app['events']->dispatch(
                new Events\RequestHandled($request, $response)
            ); 
            // 由于容器继承了ArrayAccess此处的$this->app['events']会转到容器的__get()方法,
            // __get()会调用容器的offsetGet('events')方法中解析出events实例。这涉及ArrayAccess类的特性。
            // 这里实现了触发一个RequestHandled的事件
    
            return $response;
        }
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protected function sendRequestThroughRouter($request)
        {
            $this->app->instance('request', $request); // 将request实例放入app的$instances成员
    
            Facade::clearResolvedInstance('request'); // 清理已经解析成员中对应的request的值。
    
            $this->bootstrap(); 
            // 开始启动引导,传入$bootstrappers成员给app对象的bootstrapWith(array $bootstrappers)方法,
            // 这里主要做了几件事
            // 1.触发应用启动前listen的同名事件
            // 2.从容器中make出实例并且调用本身的bootstrap()方法来启动。
            // 这里涉及到的类
            \Illuminate\Foundation\Bootstrap\LoadEnvironmentVariables::class,载入环境变量env
            \Illuminate\Foundation\Bootstrap\LoadConfiguration::class,// 载入config文件夹下的配置文件
            \Illuminate\Foundation\Bootstrap\HandleExceptions::class,// make php异常处理和相关报告
            \Illuminate\Foundation\Bootstrap\RegisterFacades::class, // make 所有的门面app.aliases和PackageManifest::class)->aliases()中的类
            \Illuminate\Foundation\Bootstrap\RegisterProviders::class,// make config下app.providers中的类
            \Illuminate\Foundation\Bootstrap\BootProviders::class,// 调用app自身的boot(),触发所有的$bootingCallbacks回调,调用$serviceProviders所有的类的boot方法,触发所有的bootedCallbacks回调。
            // 3.触发应用启动后listen的同名事件
            // 这里将通过app和容器来加载env,config目录下的文件,设置php异常配置,加载config/app.php配置的门面类,加载config/app.php服务提供者类,最后启动app对象自身boot();
            
    
            return (new Pipeline($this->app))
                        ->send($request)
                        ->through($this->app->shouldSkipMiddleware() ? [] : $this->middleware)
                        ->then($this->dispatchToRouter());
                        // 通过管道来处理中间件,然后将处理后的请求又路由转发,最后得到response对象。
        
        }
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终止应用
    public function terminate($request, $response)
        {
            $this->terminateMiddleware($request, $response); // 开始遍历所有中间件中的终止方法,如果有则立即调用。
    
            $this->app->terminate();
            // 调用app对象$terminatingCallbacks中的所有回调
        }
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总结来说,内核主要是处理请求,终止请求的功能。 其中还包括了加载app的一些必要的服务,比如配置,异常等类都是 在内核的handler过程中加载的。还包含了路由对请求的转发,以及通过管道来发送请求是通过中间件等等。