告别HTTP请求处理的混乱：使用Composer和PSR-15规范构建高效中间件架构

<code class="bash">composer require psr/http-server-middleware psr/http-server-handler</code>

<pre class="brush:php;toolbar:false;"><?php

use Psr\Http\Message\ResponseInterface;
use Psr\Http\Message\ServerRequestInterface;
use Psr\Http\Server\MiddlewareInterface;
use Psr\Http\Server\RequestHandlerInterface;
use Nyholm\Psr7\Factory\Psr17Factory; // 假设你使用一个PSR-7实现，例如Nyholm/psr7

// 1. 定义一个最终的请求处理器 (例如，你的路由处理逻辑)
class MyRequestHandler implements RequestHandlerInterface
{
    public function handle(ServerRequestInterface $request): ResponseInterface
    {
        $factory = new Psr17Factory();
        $response = $factory->createResponse(200);
        $response->getBody()->write('Hello from the application! Path: ' . $request->getUri()->getPath());
        return $response;
    }
}

// 2. 定义一个日志中间件
class LogMiddleware implements MiddlewareInterface
{
    public function process(ServerRequestInterface $request, RequestHandlerInterface $handler): ResponseInterface
    {
        error_log('Request received: ' . $request->getUri()->getPath());
        $response = $handler->handle($request); // 将请求传递给下一个处理器
        error_log('Response sent with status: ' . $response->getStatusCode());
        return $response;
    }
}

// 3. 定义一个认证中间件
class AuthMiddleware implements MiddlewareInterface
{
    public function process(ServerRequestInterface $request, RequestHandlerInterface $handler): ResponseInterface
    {
        // 简单的认证逻辑
        if (!$request->hasHeader('Authorization')) {
            $factory = new Psr17Factory();
            return $factory->createResponse(401)->withHeader('WWW-Authenticate', 'Bearer');
        }
        return $handler->handle($request); // 认证通过，继续处理
    }
}

// 4. 构建中间件管道 (通常由框架或一个调度器完成)
class MiddlewarePipeline implements RequestHandlerInterface
{
    private array $middlewares;
    private RequestHandlerInterface $finalHandler;
    private int $index = 0;

    public function __construct(array $middlewares, RequestHandlerInterface $finalHandler)
    {
        $this->middlewares = $middlewares;
        $this->finalHandler = $finalHandler;
    }

    public function handle(ServerRequestInterface $request): ResponseInterface
    {
        if (isset($this->middlewares[$this->index])) {
            $middleware = $this->middlewares[$this->index];
            $this->index++;
            return $middleware->process($request, $this); // 将自身作为下一个处理器传递
        }
        return $this->finalHandler->handle($request);
    }
}

// 5. 模拟一个请求并执行
$factory = new Psr17Factory();
$request = $factory->createServerRequest('GET', '/test');
// $request = $request->withHeader('Authorization', 'Bearer some_token'); // 取消注释以测试认证通过

$pipeline = new MiddlewarePipeline(
    [
        new LogMiddleware(),
        new AuthMiddleware(),
    ],
    new MyRequestHandler()
);

$response = $pipeline->handle($request);

echo $response->getStatusCode() . " " . $response->getReasonPhrase() . "\n";
echo (string) $response->getBody();