laravel的设计

流程

第一步

laravel的入口是 public/index.php 文件，apache或nginx会把所有请求导向该文件。该文件的代码如下：

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<?php

use Illuminate\Contracts\Http\Kernel;
use Illuminate\Http\Request;

define('LARAVEL_START', microtime(true));

/*
|--------------------------------------------------------------------------
| Check If The Application Is Under Maintenance
|--------------------------------------------------------------------------
|
| If the application is in maintenance / demo mode via the "down" command
| we will load this file so that any pre-rendered content can be shown
| instead of starting the framework, which could cause an exception.
|
*/

if (file_exists($maintenance = __DIR__.'/../storage/framework/maintenance.php')) {
    require $maintenance;
}

/*
|--------------------------------------------------------------------------
| Register The Auto Loader
|--------------------------------------------------------------------------
|
| Composer provides a convenient, automatically generated class loader for
| this application. We just need to utilize it! We'll simply require it
| into the script here so we don't need to manually load our classes.
|
*/

require __DIR__.'/../vendor/autoload.php';

/*
|--------------------------------------------------------------------------
| Run The Application
|--------------------------------------------------------------------------
|
| Once we have the application, we can handle the incoming request using
| the application's HTTP kernel. Then, we will send the response back
| to this client's browser, allowing them to enjoy our application.
|
*/

$app = require_once __DIR__.'/../bootstrap/app.php';

$kernel = $app->make(Kernel::class);

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

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

laravel的第一步是从bootstrap/app.php中获取app实例（service container）。

第二步

所有的请求进入http kernel，位置在 app/Http/Kernel.php，这个类里定义了一堆中间件数组。所有请求都需要这些中间件处理。kernel类的handle方法接受请求，返回响应。

第三步

在laravel启动过程中，最重要的是加载各个providers，这些providers可以被当作是laravel的零件。laravel的所有providers都在 config/app.php 文件中的providers数组中配置。

第四步

最重要的一个providers叫RouteServiceProvider，这个类的位置在app/Providers/RouteServiceProvider.php。

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<?php

namespace App\Providers;

use Illuminate\Cache\RateLimiting\Limit;
use Illuminate\Foundation\Support\Providers\RouteServiceProvider as ServiceProvider;
use Illuminate\Http\Request;
use Illuminate\Support\Facades\RateLimiter;
use Illuminate\Support\Facades\Route;

class RouteServiceProvider extends ServiceProvider
{
    /**
     * The path to your application's "home" route.
     *
     * Typically, users are redirected here after authentication.
     *
     * @var string
     */
    public const HOME = '/home';

    /**
     * Define your route model bindings, pattern filters, and other route configuration.
     */
    public function boot(): void
    {
        RateLimiter::for('api', function (Request $request) {
            return Limit::perMinute(60)->by($request->user()?->id ?: $request->ip());
        });

        $this->routes(function () {
            Route::middleware('api')
                ->prefix('api')
                ->group(base_path('routes/api.php'));

            Route::middleware('web')
                ->group(base_path('routes/web.php'));
        });
    }
}

路由把请求分配给controller，并运行任何特定路由中间件。

结束

handle方法返回响应，然后send方法返回内容到浏览器。

容器与依赖注入