Laravel 中的中間件是一種過(guò)濾HTTP 請(qǐng)求的機(jī)制，用於在請(qǐng)求到達(dá)路由之前檢查或修改請(qǐng)求，或在響應(yīng)返回瀏覽器之前進(jìn)行調(diào)整。它分為全局中間件和路由中間件兩種類型，前者應(yīng)用於所有請(qǐng)求，後者僅應(yīng)用於特定路由。你可以通過(guò)php artisan make:middleware 創(chuàng)建自定義中間件，並在handle() 方法中編寫(xiě)邏輯處理請(qǐng)求，如驗(yàn)證用戶權(quán)限。創(chuàng)建後需在Kernel.php 中註冊(cè)，並通過(guò)->middleware() 應(yīng)用到具體路由。中間件可接收參數(shù)，也可分組使用，以實(shí)現(xiàn)更靈活的控制。使用時(shí)應(yīng)注意保持中間件輕量，確保性能優(yōu)化。

Laravel middleware works like a filter for HTTP requests entering your application. It gives you a way to inspect or modify the request before it gets to your routes, or to alter the response before it's sent back to the browser. Think of it as a series of layers a request must pass through — each one can decide whether to let it continue, stop it entirely (like blocking unauthorized access), or even tweak things along the way.

What is Middleware in Laravel?

Middleware in Laravel is essentially a mechanism that sits between an incoming request and your application logic. It's used to handle common tasks such as authentication, logging, CORS handling, and more.

Each middleware layer can either:

• Allow the request to proceed to the next layer
• Return a response immediately (eg, redirect or error)
• Modify the request or response

For example, Laravel includes a built-in middleware that checks if a user is authenticated. If not, it redirects them to the login page.

You'll typically find middleware in the app/Http/Middleware directory.

How to Create and Use Custom Middleware

If you need custom behavior for certain routes — say, checking if a user has admin privileges — you can create your own middleware.

To generate middleware:

 php artisan make:middleware CheckAdmin

This creates a new file in the Middleware folder. Inside the handle() method, you can add your logic:

 public function handle($request, Closure $next)
{
    if (! $request->user()->isAdmin()) {
        return redirect('home');
    }

    return $next($request);
}

After writing the logic, register the middleware:

• In app/Http/Kernel.php , add it to either $middleware (global) or $routeMiddleware (for route-specific use)

Then apply it to a route:

 Route::get('/admin', function () {
    // Only accessible by admins
})->middleware('check.admin');

Types of Middleware in Laravel

There are two main types of middleware in Laravel:

1. Global Middleware
Runs on every request. Useful for things like logging or setting up global session data.

2. Route Middleware
Applied only to specific routes. Perfect for role-based access control or feature toggles.

Also worth mentioning:

• You can assign multiple middlewares to a single route
• Middlewares run in the order they're assigned
• You can short-circuit the process at any point by returning a response early

Middleware Parameters and Groups

Sometimes you need to pass parameters to your middleware — like checking for a specific permission.

In your route:

 ->middleware('role:editor');

In the middleware:

 public function handle($request, Closure $next, $role)
{
    if (! $request->user()->hasRole($role)) {
        return redirect('home');
    }

    return $next($request);
}

You can also group middleware for cleaner route definitions. For example, applying both auth and role:admin together under a name like admin.auth .

A Few Things to Keep in Mind

• Middleware should be lightweight — avoid doing heavy processing unless necessary
• Always remember to return $next($request) unless you want to block the request
• Order matters when stacking multiple middlewares
• Use middleware sparingly on high-traffic routes to keep performance optimal

基本上就這些。 Middleware 是Laravel 請(qǐng)求處理流程中非常實(shí)用的一環(huán)，理解它的工作方式能讓你更靈活地控制請(qǐng)求和響應(yīng)流程。

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