The Laravel request life cycle starts from public/index.php, loads the framework and hands it over to the HTTP kernel for processing; the kernel executes global, grouping and routing middleware, and calls next() in order to advance the process; then the framework matches the route and calls the corresponding controller method, injects dependencies through the service container; finally returns the response and executes the end processing, including closing the connection and saving the Session.
In Laravel, understanding the request lifecycle is a key step in mastering the framework's operation. From the user initiates a request to the server return a response, the entire process seems simple, but it involves the collaborative work of multiple core components. If you understand this process, debugging, optimizing and extending applications will be easier.

Request entry: Start with public/index.php
Laravel's request lifecycle starts from the public/index.php
file. You can think of it as the "door" of the entire application. This file mainly does two things:
- Introducing Composer Autoloader
- Get the Laravel application instance and process the request
This step will not directly write too much logic, but will hand over control to the core part of the framework. For example:

$kernel = $app->make(Illuminate\Contracts\Http\Kernel::class); $response = $kernel->handle($request = Illuminate\Http\Request::capture());
Here $kernel
is responsible for handling the entire request process, including middleware, routing matching, etc.
Core process: How the HTTP kernel handles requests
Laravel's HTTP kernel (usually located in App\Http\Kernel
) inherits from the framework's base class and defines three types of middleware:

- Global Middleware: Applicable to all requests
- Grouping middleware: such as
web
andapi
- Routing middleware: bind to a specific route on demand
When the request enters the kernel, it will be pre-processed by these middlewares, such as checking the login status, setting the session, etc. Then we will match the route.
The order of middleware is important. You can see their execution order in the $middleware
array in App\Http\Kernel
. If a middleware does not call next()
, the subsequent logic will be interrupted.
Routing matching and controller execution
Once the middleware passes, Laravel will look for the corresponding route. This part is defined in routes/web.php
or routes/api.php
. The framework will match the registered route based on the request method (GET, POST, etc.) and the URI.
After the match is successful, the framework will create the corresponding controller instance and call the specified method. for example:
Route::get('/user/{id}', [UserController::class, 'show']);
In this example, when accessing /user/123
, Laravel instantiates UserController
and calls the show
method, and passes the parameter id
in it.
It should be noted that Laravel uses service containers to parse controllers, so you can depend on injecting various services in the controller method.
Response return and end processing
The last step is to return the response to the client. The controller method can return a string, view, JSON, or Response
instance. Laravel automatically converts it to a suitable HTTP response.
Some "end" operations are also performed before the response is sent:
- Execute response middleware (that is, defined in
$middlewareGroups
) - Close the database connection
- Save Session Data
This part of the logic is processed in the kernel's terminate
method. Although you don't need to care about it most of the time, if you do something like logging or performance statistics, you may need to finish it here.
Basically that's it. Although the entire request life cycle seems a bit long, there is a clear division of responsibilities for each step. Understanding this process can help you develop using Laravel more efficiently.
The above is the detailed content of Understanding the Request Lifecycle in Laravel.. For more information, please follow other related articles on the PHP Chinese website!

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