这篇文章主要介绍了关于Laravel核心解读Response,有着一定的参考价值,现在分享给大家,有需要的朋友可以参考一下
前面两节我们分别讲了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(PsrHttpMessageResponseInterface的别名) | Psr规范中对服务端响应的定义 |
IlluminateHttpJsonResponse (SymfonyComponentHttpFoundationResponse的子类) | Laravel中对服务端JSON响应的定义 |
IlluminateHttpResponse (SymfonyComponentHttpFoundationResponse的子类) | Laravel中对普通的非JSON响应的定义 |
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SymfonyComponentHttpFoundationResponse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SymfonyComponentHttpFoundationResponse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); $this->setProtocolVersion('1.0'); } //设置响应的Content public function setContent($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'); $headers->remove('Content-Length'); } else { // Content-type based on the Request if (!$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-Length if ($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 protocol if ('HTTP/1.0' != $request->server->get('SERVER_PROTOCOL')) { $this->setProtocolVersion('1.1'); } // Check if we need to send extra expire info headers if ('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。
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 developer if (headers_sent()) { return $this; } // headers foreach ($this->headers->allPreserveCaseWithoutCookies() as $name => $values) { foreach ($values as $value) { header($name.': '.$value, false, $this->statusCode); } } // status header(sprintf('HTTP/%s %s %s', $this->version, $this->statusCode, $this->statusText), true, $this->statusCode); // cookies foreach ($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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