告别HTTP请求处理的混乱：使用Composer与Relay构建优雅的PSR-15中间件管道

<code class="bash">composer require relay/relay:~3.0</code>

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

require 'vendor/autoload.php';

use Psr\Http\Message\ResponseInterface;
use Psr\Http\Message\ServerRequestInterface;
use Psr\Http\Server\MiddlewareInterface;
use Psr\Http\Server\RequestHandlerInterface;
use Relay\Relay;

// --- 模拟PSR-7接口，实际项目中会使用 nyholm/psr7 等库 ---
class MockRequest implements ServerRequestInterface {
    private $attributes = [];
    public function getAttribute($name, $default = null) { return $this->attributes[$name] ?? $default; }
    public function withAttribute($name, $value) { $new = clone $this; $new->attributes[$name] = $value; return $new; }
    // ... 其他PSR-7 ServerRequestInterface 方法省略 ...
    public function getMethod() { return 'GET'; }
    public function getUri() { return new class extends \Laminas\Diactoros\Uri { public function getPath() { return '/'; } }; } // Simplified
}

class MockResponse implements ResponseInterface {
    private $body;
    private $statusCode = 200;
    public function withBody(\Psr\Http\Message\StreamInterface $body) { $new = clone $this; $new->body = $body; return $new; }
    public function getBody() { return $this->body; }
    public function getStatusCode() { return $this->statusCode; }
    public function withStatus($code, $reasonPhrase = '') { $new = clone $this; $new->statusCode = $code; return $new; }
    // ... 其他PSR-7 ResponseInterface 方法省略 ...
}
// --- 模拟结束 ---

// 1. 定义一个日志中间件
class LoggerMiddleware implements MiddlewareInterface
{
    public function process(ServerRequestInterface $request, RequestHandlerInterface $handler): ResponseInterface
    {
        echo "LoggerMiddleware: 记录请求时间...\n";
        $request = $request->withAttribute('log_time', date('Y-m-d H:i:s'));
        $response = $handler->handle($request);
        echo "LoggerMiddleware: 请求处理完毕，响应状态码：" . $response->getStatusCode() . "\n";
        return $response;
    }
}

// 2. 定义一个认证中间件
class AuthMiddleware implements MiddlewareInterface
{
    public function process(ServerRequestInterface $request, RequestHandlerInterface $handler): ResponseInterface
    {
        echo "AuthMiddleware: 检查用户认证...\n";
        // 模拟认证失败
        if ($request->getAttribute('user_id') !== 'admin') {
            echo "AuthMiddleware: 认证失败！\n";
            return (new MockResponse())->withStatus(401)->withBody(new \Laminas\Diactoros\Stream('Unauthorized'));
        }
        echo "AuthMiddleware: 认证成功！\n";
        return $handler->handle($request);
    }
}

// 3. 定义一个最终的请求处理器
class AppHandler implements RequestHandlerInterface
{
    public function handle(ServerRequestInterface $request): ResponseInterface
    {
        echo "AppHandler: 处理业务逻辑...\n";
        $logTime = $request->getAttribute('log_time', 'N/A');
        $responseBody = "Hello from App! Log time: {$logTime}\n";
        return (new MockResponse())->withBody(new \Laminas\Diactoros\Stream($responseBody));
    }
}

// 创建中间件管道
$middlewareQueue = [
    new LoggerMiddleware(),
    new AuthMiddleware(),
];

// 创建Relay实例，传入中间件队列和最终的请求处理器
$relay = new Relay($middlewareQueue, new AppHandler());

// 模拟一个请求
$request = new MockRequest();

echo "--- 第一次请求：认证失败 ---\n";
$response = $relay->handle($request);
echo "最终响应状态码: " . $response->getStatusCode() . ", 内容: " . $response->getBody()->__toString() . "\n\n";

echo "--- 第二次请求：认证成功 ---\n";
$request = $request->withAttribute('user_id', 'admin'); // 模拟已认证用户
$response = $relay->handle($request);
echo "最终响应状态码: " . $response->getStatusCode() . ", 内容: " . $response->getBody()->__toString() . "\n";

?>

<pre class="brush:php;toolbar:false;">--- 第一次请求：认证失败 ---
LoggerMiddleware: 记录请求时间...
AuthMiddleware: 检查用户认证...
AuthMiddleware: 认证失败！
LoggerMiddleware: 请求处理完毕，响应状态码：401
最终响应状态码: 401, 内容: Unauthorized

--- 第二次请求：认证成功 ---
LoggerMiddleware: 记录请求时间...
AuthMiddleware: 检查用户认证...
AuthMiddleware: 认证成功！
AppHandler: 处理业务逻辑...
LoggerMiddleware: 请求处理完毕，响应状态码：200
最终响应状态码: 200, 内容: Hello from App! Log time: 2023-10-27 10:30:00