之前两篇文章分别讲了Laravel的控制器和Request对象,在讲Request对象的那一节我们看了Request对象是如何被创建出来的以及它支持的方法都定义在哪里,讲控制器时我们详细地描述了如何找到Request对应的控制器方法然后执行处理程序的,本节我们就来说剩下的那一部分,控制器方法的执行结果是如何被转换成响应对象Response然后返回给客户端的。
让我们回到Laravel执行路由处理程序返回响应的代码块:
namespace Illuminate\Routing;
class Router implements RegistrarContract, BindingRegistrar
{ protected function runRoute(Request $request, Route $route){$request->setRouteResolver(function () use ($route) {return $route;});$this->events->dispatch(new Events\RouteMatched($route, $request));return $this->prepareResponse($request,$this->runRouteWithinStack($route, $request));}protected function runRouteWithinStack(Route $route, Request $request){$shouldSkipMiddleware = $this->container->bound('middleware.disable') &&$this->container->make('middleware.disable') === true;//收集路由和控制器里应用的中间件$middleware = $shouldSkipMiddleware ? [] : $this->gatherRouteMiddleware($route);return (new Pipeline($this->container))->send($request)->through($middleware)->then(function ($request) use ($route) {return $this->prepareResponse($request, $route->run());});}
}
在讲控制器的那一节里我们已经提到过 runRouteWithinStack
方法里是最终执行路由处理程序(控制器方法或者闭包处理程序)的地方,通过上面的代码我们也可以看到执行的结果会传递给 Router
的 prepareResponse
方法,当程序流返回到 runRoute
里后又执行了一次 prepareResponse
方法得到了要返回给客户端的Response对象, 下面我们就来详细看一下 prepareResponse
方法。
class Router implements RegistrarContract, BindingRegistrar
{/*** 通过给定值创建Response对象** @param \Symfony\Component\HttpFoundation\Request $request* @param mixed $response* @return \Illuminate\Http\Response|\Illuminate\Http\JsonResponse*/public function prepareResponse($request, $response){return static::toResponse($request, $response);}public static function toResponse($request, $response){if ($response instanceof Responsable) {$response = $response->toResponse($request);}if ($response instanceof PsrResponseInterface) {$response = (new HttpFoundationFactory)->createResponse($response);} elseif (! $response instanceof SymfonyResponse &&($response instanceof Arrayable ||$response instanceof Jsonable ||$response instanceof ArrayObject ||$response instanceof JsonSerializable ||is_array($response))) {$response = new JsonResponse($response);} elseif (! $response instanceof SymfonyResponse) {$response = new Response($response);}if ($response->getStatusCode() === Response::HTTP_NOT_MODIFIED) {$response->setNotModified();}return $response->prepare($request);}
}
在上面的代码中我们看到有三种Response:
Class Name | Representation |
---|---|
PsrResponseInterface(Psr\Http\Message\ResponseInterface的别名) | Psr规范中对服务端响应的定义 |
Illuminate\Http\JsonResponse (Symfony\Component\HttpFoundation\Response的子类) | Laravel中对服务端JSON响应的定义 |
Illuminate\Http\Response (Symfony\Component\HttpFoundation\Response的子类) | Laravel中对普通的非JSON响应的定义 |
nodejs redis,通过 prepareResponse
中的逻辑可以看到,无论路由执行结果返回的是什么值最终都会被Laravel转换为成一个Response对象,而这些对象都是Symfony\Component\HttpFoundation\Response类或者其子类的对象。从这里也就能看出来跟Request一样Laravel的Response也是依赖Symfony框架的 HttpFoundation
组件来实现的。
我们来看一下Symfony\Component\HttpFoundation\Response的构造方法:
namespace Symfony\Component\HttpFoundation;
class Response
{public function __construct($content = '', $status = 200, $headers = array()){$this->headers = new ResponseHeaderBag($headers);$this->setContent($content);$this->setStatusCode($status);$this->setProtocolVersion('1.0');}//设置响应的Contentpublic function setContent($content){if (null !== $content && !is_string($content) && !is_numeric($content) && !is_callable(array($content, '__toString'))) {throw new \UnexpectedValueException(sprintf('The Response content must be a string or object implementing __toString(), "%s" given.', gettype($content)));}$this->content = (string) $content;return $this;}
}
所以路由处理程序的返回值在创业Response对象时会设置到对象的content属性里,该属性的值就是返回给客户端的响应的响应内容。
生成Response对象后就要执行对象的 prepare
方法了,该方法定义在 Symfony\Component\HttpFoundation\Resposne
类中,其主要目的是对Response进行微调使其能够遵从HTTP/1.1协议(RFC 2616)。
namespace Symfony\Component\HttpFoundation;
class Response
{//在响应被发送给客户端之前对其进行修订使其能遵从HTTP/1.1协议public function prepare(Request $request){$headers = $this->headers;if ($this->isInformational() || $this->isEmpty()) {$this->setContent(null);$headers->remove('Content-Type');$headers->remove('Content-Length');} else {// Content-type based on the Requestif (!$headers->has('Content-Type')) {$format = $request->getRequestFormat();if (null !== $format && $mimeType = $request->getMimeType($format)) {$headers->set('Content-Type', $mimeType);}}// Fix Content-Type$charset = $this->charset ?: 'UTF-8';if (!$headers->has('Content-Type')) {$headers->set('Content-Type', 'text/html; charset='.$charset);} elseif (0 === stripos($headers->get('Content-Type'), 'text/') && false === stripos($headers->get('Content-Type'), 'charset')) {// add the charset$headers->set('Content-Type', $headers->get('Content-Type').'; charset='.$charset);}// Fix Content-Lengthif ($headers->has('Transfer-Encoding')) {$headers->remove('Content-Length');}if ($request->isMethod('HEAD')) {// cf. RFC2616 14.13$length = $headers->get('Content-Length');$this->setContent(null);if ($length) {$headers->set('Content-Length', $length);}}}// Fix protocolif ('HTTP/1.0' != $request->server->get('SERVER_PROTOCOL')) {$this->setProtocolVersion('1.1');}// Check if we need to send extra expire info headersif ('1.0' == $this->getProtocolVersion() && false !== strpos($this->headers->get('Cache-Control'), 'no-cache')) {$this->headers->set('pragma', 'no-cache');$this->headers->set('expires', -1);}$this->ensureIEOverSSLCompatibility($request);return $this;}
}
prepare
里针对各种情况设置了相应的 response header
比如 Content-Type
、 Content-Length
等等这些我们常见的首部字段。
php使用redis?创建并设置完Response后它会流经路由和框架中间件的后置操作,在中间件的后置操作里一般都是对Response进行进一步加工,最后程序流回到Http Kernel那里, Http Kernel会把Response发送给客户端,我们来看一下这部分的代码。
//入口文件public/index.php
$kernel = $app->make(Illuminate\Contracts\Http\Kernel::class);
$response = $kernel->handle($request = Illuminate\Http\Request::capture()
);
$response->send();
$kernel->terminate($request, $response);
namespace Symfony\Component\HttpFoundation;
class Response
{public function send(){$this->sendHeaders();$this->sendContent();if (function_exists('fastcgi_finish_request')) {fastcgi_finish_request();} elseif ('cli' !== PHP_SAPI) {static::closeOutputBuffers(0, true);}return $this;}//发送headers到客户端public function sendHeaders(){// headers have already been sent by the developerif (headers_sent()) {return $this;}// headersforeach ($this->headers->allPreserveCaseWithoutCookies() as $name => $values) {foreach ($values as $value) {header($name.': '.$value, false, $this->statusCode);}}// statusheader(sprintf('HTTP/%s %s %s', $this->version, $this->statusCode, $this->statusText), true, $this->statusCode);// cookiesforeach ($this->headers->getCookies() as $cookie) {if ($cookie->isRaw()) {setrawcookie($cookie->getName(), $cookie->getValue(), $cookie->getExpiresTime(), $cookie->getPath(), $cookie->getDomain(), $cookie->isSecure(), $cookie->isHttpOnly());} else {setcookie($cookie->getName(), $cookie->getValue(), $cookie->getExpiresTime(), $cookie->getPath(), $cookie->getDomain(), $cookie->isSecure(), $cookie->isHttpOnly());}}return $this;}//发送响应内容到客户端public function sendContent(){echo $this->content;return $this;}
}
send
的逻辑就非常好理解了,把之前设置好的那些headers设置到HTTP响应的首部字段里,Content会echo后被设置到HTTP响应的主体实体中。最后PHP会把完整的HTTP响应发送给客户端。
send响应后Http Kernel会执行 terminate
方法调用terminate中间件里的 terminate
方法,最后执行应用的 termiate
方法来结束整个应用生命周期(从接收请求开始到返回响应结束)。
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