Laravel 中间件加载流程

Laravel 入口 public/index.php

make(Illuminate\Contracts\Http\Kernel::class);

// 调用 App\Http\Kernel::class 中的handle方法 并传入参数
$response = $kernel->handle(
    // 传入 $request 参数
    $request = Illuminate\Http\Request::capture()
);

// 省略代码 ......

• Illuminate\Foundation\Http 请求分发类Http

/* 参看一下 __construct 控制器类 和 handle 方法 */

    /**
     * The priority-sorted list of middleware.
     *
     * Forces the listed middleware to always be in the given order.
     *
     * @var array
     */
    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,
    ];

    /**
     * The bootstrap classes for the application.
     *
     * @var array
     */
    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,
    ];

    /**
     * Create a new HTTP kernel instance.
     *
     * @param  \Illuminate\Contracts\Foundation\Application  $app
     * @param  \Illuminate\Routing\Router  $router
     * @return void
     */
    public function __construct(Application $app, Router $router)
    {
        $this->app = $app;
        $this->router = $router;

        // 参数赋值 路由赋值中间件 $this->middlewarePriority 中定义的中间件
        $router->middlewarePriority = $this->middlewarePriority;
        
        // 路由赋值中间件 参看源码 (中间件组)
        foreach ($this->middlewareGroups as $key => $middleware) {
            $router->middlewareGroup($key, $middleware);
        }

        // 路由赋值中间件 参看源码  （路由中间件）
        foreach ($this->routeMiddleware as $key => $middleware) {
            $router->aliasMiddleware($key, $middleware);
        }
    }

    /**
     * Handle an incoming HTTP request.
     *
     * @param  \Illuminate\Http\Request  $request
     * @return \Illuminate\Http\Response
     */
    public function handle($request)
    {
        try {
            // 开启CRSF防护标志 self::$httpMethodParameterOverride = true;
            $request->enableHttpMethodParameterOverride();

            // 通过路由器发送请求 
            $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);
        }

        $this->app['events']->dispatch(
            new Events\RequestHandled($request, $response)
        );

        return $response;
    }

    /**
     * Send the given request through the middleware / router.
     *
     * @param  \Illuminate\Http\Request  $request
     * @return \Illuminate\Http\Response
     */
    protected function sendRequestThroughRouter($request)
    {
        // 注册服务器容器 request
        $this->app->instance('request', $request);

        // 清除门面 request
        Facade::clearResolvedInstance('request');

        // 引导HTTP请求的应用程序 注册一些服务配置等
        $this->bootstrap();

        return (new Pipeline($this->app))
                    ->send($request)
                    ->through($this->app->shouldSkipMiddleware() ? [] : $this->middleware)
                    ->then($this->dispatchToRouter());
    }

    /**
     * Bootstrap the application for HTTP requests.
     *
     * @return void
     */
    public function bootstrap()
    {
        // 判断bootstarp是否已经加载过了
        if (! $this->app->hasBeenBootstrapped()) {
            $this->app->bootstrapWith($this->bootstrappers());
        }
    }

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