了解 Laravel 中間件：深入探討 Laravel #s 新方法

<?php
return Application::configure()
    ->withProviders()
    ->withRouting(
        web: __DIR__.'/../routes/web.php',
        // api: __DIR__.'/../routes/api.php',
        commands: __DIR__.'/../routes/console.php',
        // channels: __DIR__.'/../routes/channels.php',
    )
    ->withMiddleware(function (Middleware $middleware) {
        //
    })
    ->withExceptions(function (Exceptions $exceptions) {
        //
    })->create();
?>```



**Middleware Management**
In Laravel 11, middleware is now handled through the withMiddleware() method, which accepts a callable function. Inside this callable, you can register, modify, or remove middleware.

## 6. How to Create and Use Custom Middleware in Laravel
Creating custom middleware in Laravel allows you to extend the default behavior of your application. Here’s how to create and use custom middleware in Laravel:

Step 1: Create the Middleware
You can create middleware using the Artisan command:


php artisan make:middleware CheckAge
This command will create a new middleware class in the app/Http/Middleware directory. The newly created CheckAge.php file will look something like this:




```php
<?php

namespace App\Http\Middleware;

use Closure;
use Illuminate\Http\Request;

class CheckAge
{
    /**
     * Handle an incoming request.
     */
    public function handle(Request $request, Closure $next)
    {
        if ($request->age <= 18) {
            return redirect('home');
        }

        return $next($request);
    }
}?>```



In this example, the CheckAge middleware checks the user's age and redirects them if they are under 18. If the user passes the condition, the request continues to the next layer.

**Step 2: Register the Middleware**
Since Laravel 11 no longer uses the Http Kernel, you will need to register your middleware in the bootstrap/app.php file. Here’s how you can register your custom middleware:




```php return Application::configure()
    ->withProviders()
    ->withRouting(
        web: __DIR__.'/../routes/web.php',
    )
    ->withMiddleware(function (Middleware $middleware) {
        $middleware->alias('check.age', \App\Http\Middleware\CheckAge::class);
    })
    ->create();```



Now, your middleware alias check.age is available for use in your routes.

Step 3: Apply the Middleware to Routes
Once the middleware is registered, you can apply it to routes or route groups:




```php
<?php

Route::get('/dashboard', function () {
    // Only accessible if age > 18
})->middleware('check.age');?>```



## 7. Practical Examples of Using Middleware
Middleware can be used for a variety of tasks in Laravel. Let’s look at a few practical use cases.

**Example 1: Logging Requests**
You can create middleware to log incoming requests to a file or a logging service. This can help you monitor the behavior of your application.



```php

<?php

namespace App\Http\Middleware;

use Closure;
use Illuminate\Support\Facades\Log;
use Illuminate\Http\Request;

class LogRequest
{
    public function handle(Request $request, Closure $next)
    {
        Log::info('Request URL: ' . $request->url());

        return $next($request);
    }
}?>```



**Example 2: Checking User Roles**
You can use middleware to restrict access based on user roles. For example, only allow access to certain routes if the user has an admin role.



```php

<?php

namespace App\Http\Middleware;

use Closure;
use Illuminate\Support\Facades\Auth;

class CheckRole
{
    public function handle($request, Closure $next)
    {
        if (Auth::user() && Auth::user()->role != 'admin') {
            return redirect('/home');
        }

        return $next($request);
    }
}?>```



## 8. Best Practices for Middleware in Laravel
Here are some best practices to follow when working with middleware in Laravel:

**1. Keep Middleware Focused**
Middleware should be responsible for a single task. If you find that your middleware is doing too much, consider splitting it into smaller, more focused middleware.

**2. Use Route-Specific Middleware**
Use route-specific middleware when possible. Applying middleware globally can lead to performance overhead and unnecessary checks on routes that don’t need them.

**3. Avoid Complex Logic**
Middleware should be kept simple. Complex logic or business rules should be handled in the controller