xiaohuilam / laravel

在前面 01. HTTP 入口解析的第 54-56 行代码分析时

Lines 54 to 56 in 7028b17

    
           $response = $kernel->handle( 
        
               $request = Illuminate\Http\Request::capture() 
        
           );

我们只分析了 $request 的产生，却没有分析 $response 。
这节，我们就来研究下 Laravel 的 Response 对象: Illuminate\Http\Response。

Illuminate\Http\Response 初识

不难看出，这句代码拿到的一定是个对象。为什么？
因为在下文，就调用了他的 ->send() 方法。

laravel/public/index.php

Line 58 in 7028b17

$response->send();

那么 Illuminate\Http\Response 对象是从哪里来的呢？

在从入口到 Kernel::handle() 到管道的过程尾声，我们拿到了这句逻辑

laravel/vendor/laravel/framework/src/Illuminate/Routing/Router.php

Lines 674 to 681 in d081c91

    
           return (new Pipeline($this->container)) 
        
                           ->send($request) 
        
                           ->through($middleware) 
        
                           ->then(function ($request) use ($route) { 
        
                               return $this->prepareResponse( 
        
                                   $request, $route->run() 
        
                               ); 
        
                           });

的

laravel/vendor/laravel/framework/src/Illuminate/Routing/Router.php

Lines 678 to 680 in d081c91

    
           return $this->prepareResponse( 
        
               $request, $route->run() 
        
           );

这个 prepareResponse 是干嘛的呢？

laravel/vendor/laravel/framework/src/Illuminate/Routing/Router.php

Lines 717 to 720 in d081c91

    
           public function prepareResponse($request, $response) 
        
           { 
        
               return static::toResponse($request, $response); 
        
           }

调用了

laravel/vendor/laravel/framework/src/Illuminate/Routing/Router.php

Lines 729 to 755 in d081c91

    
           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 Model && $response->wasRecentlyCreated) { 
        
                   $response = new JsonResponse($response, 201); 
        
               } 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); 
        
           }

过程为：

判断是否为 PsrResponseInterface 对象；
则判断为模型，且刚创建，将响应头 statusCoe 强制覆盖成 HTTP 201 created ；
否则判断返回的对象是否具有序列号特征，如果是就重置成 JsonResponse；
否则的话覆盖成 Response；

于是乎，我们才可以在 controller 中大胆的直接返回字符串而转换成 Response 对象。因为在这里他帮我们转了。

经过上面这一波加工后，在 public/index.php 里面才敢执行 $response->send()

Illuminate\Http\Response::send() 的逻辑

laravel/vendor/symfony/http-foundation/Response.php

Lines 366 to 378 in d081c91

    
           public function send() 
        
           { 
        
               $this->sendHeaders(); 
        
               $this->sendContent(); 
        
               if (\function_exists('fastcgi_finish_request')) { 
        
                   fastcgi_finish_request(); 
        
               } elseif (!\in_array(\PHP_SAPI, array('cli', 'phpdbg'), true)) { 
        
                   static::closeOutputBuffers(0, true); 
        
               } 
        
               return $this; 
        
           }

调用的 sendContent 逻辑为

laravel/vendor/symfony/http-foundation/Response.php

Lines 354 to 359 in d081c91

    
           public function sendContent() 
        
           { 
        
               echo $this->content; 
        
               return $this; 
        
           }

其中的 echo 代码清晰可见，非常简单。

先于 sendContent 的 sendHeaders 的代码要稍微复杂一点

laravel/vendor/symfony/http-foundation/Response.php

Lines 324 to 347 in d081c91

    
           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); 
        
                   } 
        
               } 
        
               // cookies 
        
               foreach ($this->headers->getCookies() as $cookie) { 
        
                   header('Set-Cookie: '.$cookie->getName().strstr($cookie, '='), false, $this->statusCode); 
        
               } 
        
               // status 
        
               header(sprintf('HTTP/%s %s %s', $this->version, $this->statusCode, $this->statusText), true, $this->statusCode); 
        
               return $this; 
        
           }

先是将 http 响应头依次输出，然后将 Cookie 处理后输出。

在 send 方法的后面，还有几句

laravel/vendor/symfony/http-foundation/Response.php

Lines 371 to 375 in d081c91

    
           if (\function_exists('fastcgi_finish_request')) { 
        
               fastcgi_finish_request(); 
        
           } elseif (!\in_array(\PHP_SAPI, array('cli', 'phpdbg'), true)) { 
        
               static::closeOutputBuffers(0, true); 
        
           }

作用是判断是否是 fastcgi 或者 cli 模式调用，如果是就关闭连接、刷新缓冲区。

至此，send 逻辑就讲完了。

Kernel::terminate() 的逻辑

App\Http\Kernel 并没有 terminate 方法，一路穿透到了 Illuminate\Foundation\Http\Kernel 里面

laravel/vendor/laravel/framework/src/Illuminate/Foundation/Http/Kernel.php

Lines 187 to 192 in d081c91

    
           public function terminate($request, $response) 
        
           { 
        
               $this->terminateMiddleware($request, $response); 
        
               $this->app->terminate(); 
        
           }

Illuminate\Foundation\Http\Kernel::terminateMiddleware() 逻辑

laravel/vendor/laravel/framework/src/Illuminate/Foundation/Http/Kernel.php

Lines 201 to 221 in d081c91

    
           protected function terminateMiddleware($request, $response) 
        
           { 
        
               $middlewares = $this->app->shouldSkipMiddleware() ? [] : array_merge( 
        
                   $this->gatherRouteMiddleware($request), 
        
                   $this->middleware 
        
               ); 
        
               foreach ($middlewares as $middleware) { 
        
                   if (! is_string($middleware)) { 
        
                       continue; 
        
                   } 
        
                   list($name) = $this->parseMiddleware($middleware); 
        
                   $instance = $this->app->make($name); 
        
                   if (method_exists($instance, 'terminate')) { 
        
                       $instance->terminate($request, $response); 
        
                   } 
        
               } 
        
           }

将容器中 bind 过的中间件 terminate() 掉。

而这句就比较好理解了，直接调用了容器的 terminate()

laravel/vendor/laravel/framework/src/Illuminate/Foundation/Http/Kernel.php

Line 191 in d081c91

$this->app->terminate();

容器的 terminate() 方法也比较简单，触发 $terminatingCallbacks 注册的回调。

laravel/vendor/laravel/framework/src/Illuminate/Foundation/Application.php

Lines 962 to 967 in d081c91

    
           public function terminate() 
        
           { 
        
               foreach ($this->terminatingCallbacks as $terminating) { 
        
                   $this->call($terminating); 
        
               } 
        
           }

PHP的不常驻特性，一个请求完了就自动回收资源，那么除了需要触发 $terminatingCallbacks 回调外，为什么还要实现 terminate() 呢？

Laravel 为我们提供了一个 php artisan serve 的便捷服务器，启动后 Application 对象是常驻的。所以需要单独回收需要回收的资源。

php artisan serve 的本质也是 php -S，详细资料 PHP 的命令行模式>内置Web Server。

扩展阅读：在 Laravel 5.3 以前，Kernel::terminate() 还调用了 fastcgi_finish_request()。后来移除了，主要原因是因为这个函数会阻断 http 响应的头和 body，造成部分特殊情况的 session 问题，不过也可能还有其他原因。

	$response = $kernel->handle(
	$request = Illuminate\Http\Request::capture()
	);

	return (new Pipeline($this->container))
	->send($request)
	->through($middleware)
	->then(function ($request) use ($route) {
	return $this->prepareResponse(
	$request, $route->run()
	);
	});

	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 Model && $response->wasRecentlyCreated) {
	$response = new JsonResponse($response, 201);
	} 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);
	}

	public function send()
	{
	$this->sendHeaders();
	$this->sendContent();

	if (\function_exists('fastcgi_finish_request')) {
	fastcgi_finish_request();
	} elseif (!\in_array(\PHP_SAPI, array('cli', 'phpdbg'), true)) {
	static::closeOutputBuffers(0, true);
	}

	return $this;
	}

	public function sendContent()
	{
	echo $this->content;

	return $this;
	}

	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);
	}
	}

	// cookies
	foreach ($this->headers->getCookies() as $cookie) {
	header('Set-Cookie: '.$cookie->getName().strstr($cookie, '='), false, $this->statusCode);
	}

	// status
	header(sprintf('HTTP/%s %s %s', $this->version, $this->statusCode, $this->statusText), true, $this->statusCode);

	return $this;
	}

	public function terminate($request, $response)
	{
	$this->terminateMiddleware($request, $response);

	$this->app->terminate();
	}

	protected function terminateMiddleware($request, $response)
	{
	$middlewares = $this->app->shouldSkipMiddleware() ? [] : array_merge(
	$this->gatherRouteMiddleware($request),
	$this->middleware
	);

	foreach ($middlewares as $middleware) {
	if (! is_string($middleware)) {
	continue;
	}

	list($name) = $this->parseMiddleware($middleware);

	$instance = $this->app->make($name);

	if (method_exists($instance, 'terminate')) {
	$instance->terminate($request, $response);
	}
	}
	}

	public function terminate()
	{
	foreach ($this->terminatingCallbacks as $terminating) {
	$this->call($terminating);
	}
	}

14. Response 对象和 Kernel::terminate

Illuminate\Http\Response 初识

Illuminate\Http\Response::send() 的逻辑

Kernel::terminate() 的逻辑