PHP中的中间件：如何实现请求预处理

interface MiddlewareInterface {
    public function process(Request $request, callable $next): Response;
}

class AuthenticationMiddleware implements MiddlewareInterface {
    public function process(Request $request, callable $next): Response {
        // 身份验证逻辑
        if (!isAuthenticated($request)) {
            return new Response('Unauthorized', 401);
        }

        // 调用下一个中间件
        return $next($request);
    }
}

class MiddlewareDispatcher {
    private array $middlewares = [];

    public function add(MiddlewareInterface $middleware): void {
        $this->middlewares[] = $middleware;
    }

    public function dispatch(Request $request, callable $coreApp): Response {
        // 创建中间件链
        $middlewareChain = array_reduce(
            array_reverse($this->middlewares),
            fn ($next, $middleware) => fn ($request) => $middleware->process($request, $next),
            $coreApp // 核心应用逻辑作为链的终点
        );

        // 执行中间件链
        return $middlewareChain($request);
    }
}

// 使用示例
$dispatcher = new MiddlewareDispatcher();
$dispatcher->add(new AuthenticationMiddleware());
$dispatcher->add(new LoggingMiddleware());

$response = $dispatcher->dispatch($request, function (Request $request): Response {
    // 核心应用逻辑
    return new Response('Hello, World!');
});

echo $response->getBody();

// app/Http/Kernel.php
protected $middleware = [
    // 全局中间件
    \App\Http\Middleware\TrustProxies::class,
    \App\Http\Middleware\PreventRequestsDuringMaintenance::class,
    \App\Http\Middleware\TrimStrings::class,
    \App\Http\Middleware\ConvertEmptyStringsToNull::class,
];

protected $routeMiddleware = [
    'auth' => \App\Http\Middleware\Authenticate::class,
    'cache' => \App\Http\Middleware\CacheResponse::class,
];

// 在路由中使用中间件
Route::get('/profile', [ProfileController::class, 'show'])->middleware('auth');

use PHPUnit\Framework\TestCase;

class AuthenticationMiddlewareTest extends TestCase {
    public function testAuthenticatedUser(): void {
        $request = new Request(['headers' => ['Authorization' => 'Bearer valid_token']]);
        $next = function (Request $request): Response {
            return new Response('OK');
        };

        $middleware = new AuthenticationMiddleware();
        $response = $middleware->process($request, $next);

        $this->assertEquals('OK', $response->getBody());
    }

    public function testUnauthenticatedUser(): void {
        $request = new Request();
        $next = function (Request $request): Response {
            return new Response('OK');
        };

        $middleware = new AuthenticationMiddleware();
        $response = $middleware->process($request, $next);

        $this->assertEquals('Unauthorized', $response->getBody());
        $this->assertEquals(401, $response->getStatusCode());
    }
}