第七章：解析HTTP内核

约 1442 字大约 5 分钟

2025-07-08

现在我们来到了"第三阶段"：从app中得到容器中装填好的内核实例(上一步我们已经把内核绑定到了容器中)。

注意这里的"装填"，实际是执行容器类中的bind方法，进行一次键值对绑定的意思。其中键值对中的值，并不是真实存在的对象实体，而是实现对象的闭包。

对应的是下面这行代码：

$kernel = $app->make(Illuminate\Contracts\Http\Kernel::class);

我们来重点看一下make方法：

/**
 * Resolve the given type from the container.
 *
 * @param  string  $abstract
 * @param  array  $parameters
 * @return mixed
 *
 * @throws \Illuminate\Contracts\Container\BindingResolutionException
 */
public function make($abstract, array $parameters = [])
{
    return $this->resolve($abstract, $parameters);
}

vendor/laravel/framework/src/Illuminate/Foundation/Application.php

我们又重新回到了resolve方法，在第四章中，我们已经讲解过了resolve方法的代码。因此这里，我们就简单理解为，得到之前"装填"在容器上的内核实例即可。

我们需要重点关注一下Kernel类的结构，下面是App\Http\Kernel类的源代码：

<?php

namespace App\Http;

use Illuminate\Foundation\Http\Kernel as HttpKernel;

class Kernel extends HttpKernel
{
    /**
     * The application's global HTTP middleware stack.
     *
     * These middleware are run during every request to your application.
     *
     * @var array
     */
    protected $middleware = [
        \App\Http\Middleware\TrustProxies::class,
        \App\Http\Middleware\CheckForMaintenanceMode::class,
        \Illuminate\Foundation\Http\Middleware\ValidatePostSize::class,
        \App\Http\Middleware\TrimStrings::class,
        \Illuminate\Foundation\Http\Middleware\ConvertEmptyStringsToNull::class,
    ];

    /**
     * The application's route middleware groups.
     *
     * @var array
     */
    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',
        ],
    ];

    /**
     * The application's route middleware.
     *
     * These middleware may be assigned to groups or used individually.
     *
     * @var array
     */
    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,
    ];

    /**
     * The priority-sorted list of middleware.
     *
     * This forces non-global middleware to always be in the given order.
     *
     * @var array
     */
    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,
    ];
}

app/Http/Kernel.php

可以看到Kernel类只是在继承HttpKernel类的基础上，自定义了一些成员变量。我们继续看这个HttpKernel类：

<?php

namespace Illuminate\Foundation\Http;

use Exception;
use Throwable;
use Illuminate\Routing\Router;
use Illuminate\Routing\Pipeline;
use Illuminate\Support\Facades\Facade;
use Illuminate\Contracts\Debug\ExceptionHandler;
use Illuminate\Contracts\Foundation\Application;
use Illuminate\Contracts\Http\Kernel as KernelContract;
use Symfony\Component\Debug\Exception\FatalThrowableError;

class Kernel implements KernelContract
{
    /**
     * The application implementation.
     *
     * @var \Illuminate\Contracts\Foundation\Application
     */
    protected $app;

    /**
     * The router instance.
     *
     * @var \Illuminate\Routing\Router
     */
    protected $router;

    /**
     * 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,
    ];

    /**
     * The application's middleware stack.
     *
     * @var array
     */
    protected $middleware = [];

    /**
     * The application's route middleware groups.
     *
     * @var array
     */
    protected $middlewareGroups = [];

    /**
     * The application's route middleware.
     *
     * @var array
     */
    protected $routeMiddleware = [];

    /**
     * The priority-sorted list of middleware.
     *
     * Forces non-global 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,
    ];

    /**
     * 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;

        $router->middlewarePriority = $this->middlewarePriority;

        foreach ($this->middlewareGroups as $key => $middleware) {
            $router->middlewareGroup($key, $middleware);
        }

        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 {
            $request->enableHttpMethodParameterOverride();

            $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)
    {
        $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());
    }

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

    /**
     * Get the route dispatcher callback.
     *
     * @return \Closure
     */
    protected function dispatchToRouter()
    {
        return function ($request) {
            $this->app->instance('request', $request);

            return $this->router->dispatch($request);
        };
    }

    /**
     * Call the terminate method on any terminable middleware.
     *
     * @param  \Illuminate\Http\Request  $request
     * @param  \Illuminate\Http\Response  $response
     * @return void
     */
    public function terminate($request, $response)
    {
        $this->terminateMiddleware($request, $response);

        $this->app->terminate();
    }

    /**
     * Call the terminate method on any terminable middleware.
     *
     * @param  \Illuminate\Http\Request  $request
     * @param  \Illuminate\Http\Response  $response
     * @return void
     */
    protected function terminateMiddleware($request, $response)
    {
        $middlewares = $this->app->shouldSkipMiddleware() ? [] : array_merge(
            $this->gatherRouteMiddleware($request),
            $this->middleware
        );

        foreach ($middlewares as $middleware) {
            if (! is_string($middleware)) {
                continue;
            }

            [$name] = $this->parseMiddleware($middleware);

            $instance = $this->app->make($name);

            if (method_exists($instance, 'terminate')) {
                $instance->terminate($request, $response);
            }
        }
    }

    /**
     * Gather the route middleware for the given request.
     *
     * @param  \Illuminate\Http\Request  $request
     * @return array
     */
    protected function gatherRouteMiddleware($request)
    {
        if ($route = $request->route()) {
            return $this->router->gatherRouteMiddleware($route);
        }

        return [];
    }

    /**
     * Parse a middleware string to get the name and parameters.
     *
     * @param  string  $middleware
     * @return array
     */
    protected function parseMiddleware($middleware)
    {
        [$name, $parameters] = array_pad(explode(':', $middleware, 2), 2, []);

        if (is_string($parameters)) {
            $parameters = explode(',', $parameters);
        }

        return [$name, $parameters];
    }

    /**
     * Determine if the kernel has a given middleware.
     *
     * @param  string  $middleware
     * @return bool
     */
    public function hasMiddleware($middleware)
    {
        return in_array($middleware, $this->middleware);
    }

    /**
     * Add a new middleware to beginning of the stack if it does not already exist.
     *
     * @param  string  $middleware
     * @return $this
     */
    public function prependMiddleware($middleware)
    {
        if (array_search($middleware, $this->middleware) === false) {
            array_unshift($this->middleware, $middleware);
        }

        return $this;
    }

    /**
     * Add a new middleware to end of the stack if it does not already exist.
     *
     * @param  string  $middleware
     * @return $this
     */
    public function pushMiddleware($middleware)
    {
        if (array_search($middleware, $this->middleware) === false) {
            $this->middleware[] = $middleware;
        }

        return $this;
    }

    /**
     * Get the bootstrap classes for the application.
     *
     * @return array
     */
    protected function bootstrappers()
    {
        return $this->bootstrappers;
    }

    /**
     * Report the exception to the exception handler.
     *
     * @param  \Exception  $e
     * @return void
     */
    protected function reportException(Exception $e)
    {
        $this->app[ExceptionHandler::class]->report($e);
    }

    /**
     * Render the exception to a response.
     *
     * @param  \Illuminate\Http\Request  $request
     * @param  \Exception  $e
     * @return \Symfony\Component\HttpFoundation\Response
     */
    protected function renderException($request, Exception $e)
    {
        return $this->app[ExceptionHandler::class]->render($request, $e);
    }

    /**
     * Get the application's route middleware groups.
     *
     * @return array
     */
    public function getMiddlewareGroups()
    {
        return $this->middlewareGroups;
    }

    /**
     * Get the application's route middleware.
     *
     * @return array
     */
    public function getRouteMiddleware()
    {
        return $this->routeMiddleware;
    }

    /**
     * Get the Laravel application instance.
     *
     * @return \Illuminate\Contracts\Foundation\Application
     */
    public function getApplication()
    {
        return $this->app;
    }
}