[项目名]/public/index.php

$app = require_once __DIR__.'/../bootstrap/app.php';
//获得Http内核Kernel的示例；构造HttpKernel
$kernel = $app->make(Kernel::class);
//处理请求和响应；发送响应信息
$response = tap($kernel->handle(
    $request = Request::capture()
))->send();
//结束所有中间件以及可终止程序;完成
$kernel->terminate($request, $response);

[项目名]/bootstrap/app.php

<?php

$app = new Illuminate\Foundation\Application(
    $_ENV['APP_BASE_PATH'] ?? dirname(__DIR__)
);
//设置接口类的实现类，并使用单例模式实例化实现类。
//注册HttpKernel
$app->singleton(
    Illuminate\Contracts\Http\Kernel::class,
    App\Http\Kernel::class
);
//注册ConsoleKernel
$app->singleton(
    Illuminate\Contracts\Console\Kernel::class,
    App\Console\Kernel::class
);
//异常处理
$app->singleton(
    Illuminate\Contracts\Debug\ExceptionHandler::class,
    App\Exceptions\Handler::class
);
return $app;

[项目名]/Http/Kernel.php

<?php

namespace App\Http;

use Illuminate\Foundation\Http\Kernel as HttpKernel;

class Kernel extends HttpKernel
{

    protected $middleware = [
        \App\Http\Middleware\TrustProxies::class,
        \Fruitcake\Cors\HandleCors::class,
        \App\Http\Middleware\PreventRequestsDuringMaintenance::class,
        \Illuminate\Foundation\Http\Middleware\ValidatePostSize::class,
        \App\Http\Middleware\TrimStrings::class,
        \Illuminate\Foundation\Http\Middleware\ConvertEmptyStringsToNull::class,
        \Illuminate\Session\Middleware\StartSession::class,
    ];

    protected $middlewareGroups = [
        'web' => [
            \App\Http\Middleware\EncryptCookies::class,
            \Illuminate\Cookie\Middleware\AddQueuedCookiesToResponse::class,
            \Illuminate\Session\Middleware\StartSession::class,
            \Illuminate\View\Middleware\ShareErrorsFromSession::class,
            \App\Http\Middleware\VerifyCsrfToken::class,
            \Illuminate\Routing\Middleware\SubstituteBindings::class,
            \App\Http\Middleware\Language::class, //语言包中间件注册。
        ],

        'api' => [
            'throttle:api',
            \Illuminate\Routing\Middleware\SubstituteBindings::class,
        ],
    ];

    protected $routeMiddleware = [
        'auth' => \App\Http\Middleware\Authenticate::class,
        'auth.basic' => \Illuminate\Auth\Middleware\AuthenticateWithBasicAuth::class,
        'cache.headers' => \Illuminate\Http\Middleware\SetCacheHeaders::class,
        'can' => \Illuminate\Auth\Middleware\Authorize::class,
        'guest' => \App\Http\Middleware\RedirectIfAuthenticated::class,
        'password.confirm' => \Illuminate\Auth\Middleware\RequirePassword::class,
        'signed' => \Illuminate\Routing\Middleware\ValidateSignature::class,
        'throttle' => \Illuminate\Routing\Middleware\ThrottleRequests::class,
        'verified' => \Illuminate\Auth\Middleware\EnsureEmailIsVerified::class,
    ];
}

1. 入口页，public/index.php；引入了 bootstrap 目录下的 app.php，通过 make 方法实例出一个 kernel 对象，Kernel 类是在 Illuminate\Contracts\Http\Kernel ，打印出 Kernel 对象，发现有很多 protected 的属性，简单罗列一下：

* middleware
* middlewareGroups
* routeMiddleware
* app
* router
* bootstrappers
* middlewarePriority

重点看 app 属性，app 属性实际上是一个 Illuminate\Foundation\Application 的实例，里面又包含很多属性值，主要的属性有：

* loadedProviders
* bindings
* instances
* aliases

接着调用了 kernel 类的 handle 方法，传入一个 request 请求，request 请求继承了 SymfonyRequest，并调用了一个 capture 方法，并将返回的值返回给 response 变量。整个流程基本到此为止。
，难道就这么简单，当然不是，请求进来之后，kernel 类做了一系列的验证，分发，处理，包括表单验证，中间件，日志记录，调用控制器，查询数据等等.... 如果能把这中间的整个流程全部搞清楚，并理解为什么这么做，那么你就可以算个咖了，起码是个中咖！

$response = tap($kernel->handle(
    $request = Request::capture()
))->send();

$kernel->terminate($request, $response);

2. /bootstrap/app.php

// 创建容器$app;参数为应用程序根目录
$app = new Illuminate\Foundation\Application(
    $_ENV['APP_BASE_PATH'] ?? dirname(__DIR__)
);

该类是框架核心类，负责启动框架，以及调动其他类提供的功能。
该类继承了Illuminate\Container\Container类，可见该类也是个容器。是整个框架最大的容器；

执行流程

1加载框架类库，创建容器，接收request请求。
2以管道的设计模式 执行部分中间件
3路由解析调度
4实例化当前控制器
5执行web中间件
6执行控制器中间件
7执行控制器操作
8返回response
9接收框架