# PSR 7 与值对象（Value Objects） ***** Slim supports[PSR-7](https://github.com/php-fig/http-message)interfaces for its Request and Response objects. This makes Slim flexible because it can use*any*PSR-7 implementation. For example, you could return an instance of`GuzzleHttp\Psr7\CachingStream`or any instance returned by the`GuzzleHttp\Psr7\stream_for()`function. > Slim为其请求和响应对象支持[PSR-7](https://github.com/php-fig/http-message)接口。这使得Slim非常灵活，因为它可以使用任何PSR-7实现。例如，您可以返回 `GuzzleHttp\Psr7\CachingStream` 的实例，或者 `GuzzleHttp\Psr7\stream_for()` 函数返回的任何实例。 Slim provides its own PSR-7 implementation so that it works out of the box. However, you are free to replace Slim’s default PSR-7 objects with a third-party implementation. Just override the application container’s`request`and`response`services so they return an instance of`Psr\Http\Message\ServerRequestInterface`and`Psr\Http\Message\ResponseInterface`, respectively. Slim提供了自己的PSR-7实现，因此可以开箱即用。但是，您可以使用第三方实现替换Slim的默认PSR-7对象。只需覆盖应用程序容器的`请求`和`响应`服务，以便它们分别返回 `Psr\Http\Message\ServerRequestInterface` 和 `Psr\Http\Message\ResponseInterface` 的实例。 # 值对象 Request and Response objects are[*immutable value objects*](http://en.wikipedia.org/wiki/Value_object). They can be “changed” only by requesting a cloned version that has updated property values. Value objects have a nominal overhead because they must be cloned when their properties are updated. This overhead does not affect performance in any meaningful way. > 请求和响应对象是[*immutable value objects*](http://en.wikipedia.org/wiki/Value_object)。只能通过请求具有更新属性值的克隆版本来“更改”它们。值对象有名义上的开销，因为必须在更新其属性时克隆它们。这种开销不会以任何有意义的方式影响性能。 You can request a copy of a value object by invoking any of its PSR-7 interface methods (these methods typically have a`with`prefix). For example, a PSR-7 Response object has a`withHeader($name, $value)`method that returns a cloned value object with the new HTTP header. > 您可以通过调用值对象的任何PSR-7接口方法(这些方法通常具有`with` 前缀)来请求值对象的副本。例如，一个PSR-7响应对象有一个 `withHeader($name， $value)` 方法，该方法用新的HTTP头返回一个克隆的值对象。 ~~~php <?php use Psr\Http\Message\ResponseInterface as Response; use Psr\Http\Message\ServerRequestInterface as Request; use Slim\Factory\AppFactory; require __DIR__ . '/../vendor/autoload.php'; $app = AppFactory::create(); $app->get('/foo', function (Request $request, Response $response, array $args) { $payload = json_encode(['hello' => 'world'], JSON_PRETTY_PRINT); $response->getBody()->write($payload); return $response->withHeader('Content-Type', 'application/json'); }); $app->run(); ~~~ > PSR-7接口提供了这些方法来转换请求和响应对象: * `withProtocolVersion($version)` * `withHeader($name, $value)` * `withAddedHeader($name, $value)` * `withoutHeader($name)` * `withBody(StreamInterface $body)` > PSR-7接口提供了这些方法来转换请求对象: * `withMethod($method)` * `withUri(UriInterface $uri, $preserveHost = false)` * `withCookieParams(array $cookies)` * `withQueryParams(array $query)` * `withUploadedFiles(array $uploadedFiles)` * `withParsedBody($data)` * `withAttribute($name, $value)` * `withoutAttribute($name)` > PSR-7接口提供了这些方法来转换响应对象: * `withStatus($code, $reasonPhrase = '') ` > 有关这些方法的更多信息，请参阅[PSR-7文档](http://www.php-fig.org/psr/psr-7/)。 [ PSR-7 HTTP 消息接口规范翻译文档](https://learnku.com/docs/psr/psr-7-http-message/1616)