[原创] Laravel 启动流程

目录

• 1. 程序启动准备
  • 1.1 容器基础配置
  • 1.2 核心类绑定
  • 1.3 实例化 Http 核心类
• 2. 请求实例化
• 3. 请求处理
  • 3.1 请求处理环境初始化
    • 1. 环境监测 IlluminateFoundationBootstrapLoadEnvironmentVariables::class
    • 2. 配置加载 IlluminateFoundationBootstrapLoadConfiguration::class
    • 3. 常处理 IlluminateFoundationBootstrapHandleExceptions::class
    • 4. 外观注册 IlluminateFoundationBootstrapRegisterFacades::class
    • 5. 服务提供者注册 IlluminateFoundationBootstrapRegisterProviders::class
    • 6. 启动提供者 IlluminateFoundationBootstrapBootProviders::class
  • 3.2 路由处理请求
  • 3.3 处理返回的 Response
• 4. 响应发送和程序终止
  • 4.1 响应的发送
  • 4.2 请求中止

Laravel 5.5
请求到响应的整个执行阶段归纳为 4 个:

1. 程序启动准备阶段
   • 文件自动加载
   • 服务容器实例化
   • 基础服务提供者的注册
   • 核心类的实例化
2. 请求实例化阶段
   • 实例化 Request 实例
3. 请求处理阶段
   • 准备请求处理的环境
   • 将请求实例通过中间件处理 及 通过路由和控制器的分发控制
4. 响应发送和程序终止阶段
   • 将响应内容返回给客户端
   • 记录与客户端有关的信息等

1. 程序启动准备

程序入口在 index.php 中

require __DIR__.'/../vendor/autoload.php';

$app = require_once __DIR__.'/../bootstrap/app.php';	# 获取服务容器实例

$kernel = $app->make(IlluminateContractsHttpKernel::class);

$response = $kernel->handle(
    $request = IlluminateHttpRequest::capture()
);

$response->send();

$kernel->terminate($request, $response);

创建服务容器实例

服务容器的创建在 bootstrapapp.php 中进行.

$app = new IlluminateFoundationApplication(
    realpath(__DIR__.'/../')
);

1.1 容器基础配置

容器 Application 的构造函数:

public function __construct($basePath = null)
{
    if ($basePath) {
        $this->setBasePath($basePath);
    }

    $this->registerBaseBindings();

    $this->registerBaseServiceProviders();

    $this->registerCoreContainerAliases();
}

构造函数 主要完成以下基本配置:

• 目录路径(绑定到容器中, 并提供类方法获取子目录)

  public function setBasePath($basePath)
  {
      $this->basePath = rtrim($basePath, '/');
  
      $this->bindPathsInContainer();
  
      return $this;
  }
  
  protected function bindPathsInContainer()
      {
          $this->instance('path', $this->path());
          $this->instance('path.base', $this->basePath());
          $this->instance('path.lang', $this->langPath());
          $this->instance('path.config', $this->configPath());
          $this->instance('path.public', $this->publicPath());
          $this->instance('path.storage', $this->storagePath());
          $this->instance('path.database', $this->databasePath());
          $this->instance('path.resources', $this->resourcePath());
          $this->instance('path.bootstrap', $this->bootstrapPath());
      }
  

• 绑定容器自身

  protected function registerBaseBindings()
  {
      static::setInstance($this);
  
      $this->instance('app', $this);
  
      $this->instance(Container::class, $this);
  
      $this->instance(PackageManifest::class, new PackageManifest(
          new Filesystem, $this->basePath(), $this->getCachedPackagesPath()
      ));
  }
  

• 基础服务注册( Event, Log, Route)

  protected function registerBaseServiceProviders()
  {
      $this->register(new EventServiceProvider($this));
  
      $this->register(new LogServiceProvider($this));
  
      $this->register(new RoutingServiceProvider($this));
  }
  

• 别名注册

  多个接口名 对应一个简短别名, 后续在注册服务时只需绑定到别名上即可 (而不必绑定到具体接口名)

  public function registerCoreContainerAliases()
  {
      foreach ([
          'app'                  => [IlluminateFoundationApplication::class, IlluminateContractsContainerContainer::class, IlluminateContractsFoundationApplication::class,  PsrContainerContainerInterface::class],
          'auth'                 => [IlluminateAuthAuthManager::class, IlluminateContractsAuthFactory::class],
          'auth.driver'          => [IlluminateContractsAuthGuard::class],
          'blade.compiler'       => [IlluminateViewCompilersBladeCompiler::class],
          'cache'                => [IlluminateCacheCacheManager::class, IlluminateContractsCacheFactory::class],
          'cache.store'          => [IlluminateCacheRepository::class, IlluminateContractsCacheRepository::class],
          'config'               => [IlluminateConfigRepository::class, IlluminateContractsConfigRepository::class],
          'cookie'               => [IlluminateCookieCookieJar::class, IlluminateContractsCookieFactory::class, IlluminateContractsCookieQueueingFactory::class],
          'encrypter'            => [IlluminateEncryptionEncrypter::class, IlluminateContractsEncryptionEncrypter::class],
          'db'                   => [IlluminateDatabaseDatabaseManager::class],
          'db.connection'        => [IlluminateDatabaseConnection::class, IlluminateDatabaseConnectionInterface::class],
          'events'               => [IlluminateEventsDispatcher::class, IlluminateContractsEventsDispatcher::class],
          'files'                => [IlluminateFilesystemFilesystem::class],
          'filesystem'           => [IlluminateFilesystemFilesystemManager::class, IlluminateContractsFilesystemFactory::class],
          'filesystem.disk'      => [IlluminateContractsFilesystemFilesystem::class],
          'filesystem.cloud'     => [IlluminateContractsFilesystemCloud::class],
          'hash'                 => [IlluminateContractsHashingHasher::class],
          'translator'           => [IlluminateTranslationTranslator::class, IlluminateContractsTranslationTranslator::class],
          'log'                  => [IlluminateLogWriter::class, IlluminateContractsLoggingLog::class, PsrLogLoggerInterface::class],
          'mailer'               => [IlluminateMailMailer::class, IlluminateContractsMailMailer::class, IlluminateContractsMailMailQueue::class],
          'auth.password'        => [IlluminateAuthPasswordsPasswordBrokerManager::class, IlluminateContractsAuthPasswordBrokerFactory::class],
          'auth.password.broker' => [IlluminateAuthPasswordsPasswordBroker::class, IlluminateContractsAuthPasswordBroker::class],
          'queue'                => [IlluminateQueueQueueManager::class, IlluminateContractsQueueFactory::class, IlluminateContractsQueueMonitor::class],
          'queue.connection'     => [IlluminateContractsQueueQueue::class],
          'queue.failer'         => [IlluminateQueueFailedFailedJobProviderInterface::class],
          'redirect'             => [IlluminateRoutingRedirector::class],
          'redis'                => [IlluminateRedisRedisManager::class, IlluminateContractsRedisFactory::class],
          'request'              => [IlluminateHttpRequest::class, SymfonyComponentHttpFoundationRequest::class],
          'router'               => [IlluminateRoutingRouter::class, IlluminateContractsRoutingRegistrar::class, IlluminateContractsRoutingBindingRegistrar::class],
          'session'              => [IlluminateSessionSessionManager::class],
          'session.store'        => [IlluminateSessionStore::class, IlluminateContractsSessionSession::class],
          'url'                  => [IlluminateRoutingUrlGenerator::class, IlluminateContractsRoutingUrlGenerator::class],
          'validator'            => [IlluminateValidationFactory::class, IlluminateContractsValidationFactory::class],
          'view'                 => [IlluminateViewFactory::class, IlluminateContractsViewFactory::class],
      ] as $key => $aliases) {
          foreach ($aliases as $alias) {
              $this->alias($key, $alias);
          }
      }
  }
  

1.2 核心类绑定

$app->singleton(
    IlluminateContractsHttpKernel::class,
    AppHttpKernel::class
);

$app->singleton(
    IlluminateContractsConsoleKernel::class,
    AppConsoleKernel::class
);

$app->singleton(
    IlluminateContractsDebugExceptionHandler::class,
    AppExceptionsHandler::class
);

绑定重要接口:

• Http 核心类
• 命令行 核心类
• 异常处理类

1.3 实例化 Http 核心类

$kernel = $app->make(IlluminateContractsHttpKernel::class);

Http 核心类的构造函数

public function __construct(Application $app, Router $router)
{
    $this->app = $app;
    $this->router = $router;

    $router->middlewarePriority = $this->middlewarePriority;

    foreach ($this->middlewareGroups as $key => $middleware) {
        $router->middlewareGroup($key, $middleware);
    }

    foreach ($this->routeMiddleware as $key => $middleware) {
        $router->aliasMiddleware($key, $middleware);
    }
}

上述过程主要做的事是将中间件赋值给路由

• 中间件顺序优先级列表
• 中间件组
• 中间件别名

核心类 app/Http/Kernel.php

<?php

namespace AppHttp;

use IlluminateFoundationHttpKernel as HttpKernel;

class Kernel extends HttpKernel
{
    // 全局中间件，最先调用
    protected $middleware = [

        // 检测是否应用是否进入『维护模式』
        // 见：https://d.laravel-china.org/docs/5.5/configuration#maintenance-mode
        IlluminateFoundationHttpMiddlewareCheckForMaintenanceMode::class,

        // 检测请求的数据是否过大
        IlluminateFoundationHttpMiddlewareValidatePostSize::class,

        // 对提交的请求参数进行 PHP 函数 `trim()` 处理
        AppHttpMiddlewareTrimStrings::class,

        // 将提交请求参数中空子串转换为 null
        IlluminateFoundationHttpMiddlewareConvertEmptyStringsToNull::class,

        // 修正代理服务器后的服务器参数
        AppHttpMiddlewareTrustProxies::class,
    ];

    // 定义中间件组
    protected $middlewareGroups = [

        // Web 中间件组，应用于 routes/web.php 路由文件
        'web' => [
            // Cookie 加密解密
            AppHttpMiddlewareEncryptCookies::class,

            // 将 Cookie 添加到响应中
            IlluminateCookieMiddlewareAddQueuedCookiesToResponse::class,

            // 开启会话
            IlluminateSessionMiddlewareStartSession::class,

            // 认证用户，此中间件以后 Auth 类才能生效
            // 见：https://d.laravel-china.org/docs/5.5/authentication
            IlluminateSessionMiddlewareAuthenticateSession::class,

            // 将系统的错误数据注入到视图变量 $errors 中
            IlluminateViewMiddlewareShareErrorsFromSession::class,

            // 检验 CSRF ，防止跨站请求伪造的安全威胁
            // 见：https://d.laravel-china.org/docs/5.5/csrf
            AppHttpMiddlewareVerifyCsrfToken::class,

            // 处理路由绑定
            // 见：https://d.laravel-china.org/docs/5.5/routing#route-model-binding
            IlluminateRoutingMiddlewareSubstituteBindings::class,
        ],

        // API 中间件组，应用于 routes/api.php 路由文件
        'api' => [
            // 使用别名来调用中间件
            // 请见：https://d.laravel-china.org/docs/5.5/middleware#为路由分配中间件
            'throttle:60,1',
            'bindings',
        ],
    ];

    // 中间件别名设置，允许你使用别名调用中间件，例如上面的 api 中间件组调用
    protected $routeMiddleware = [

        // 只有登录用户才能访问，我们在控制器的构造方法中大量使用
        'auth' => IlluminateAuthMiddlewareAuthenticate::class,

        // HTTP Basic Auth 认证
        'auth.basic' => IlluminateAuthMiddlewareAuthenticateWithBasicAuth::class,

        // 处理路由绑定
        // 见：https://d.laravel-china.org/docs/5.5/routing#route-model-binding
        'bindings' => IlluminateRoutingMiddlewareSubstituteBindings::class,

        // 用户授权功能
        'can' => IlluminateAuthMiddlewareAuthorize::class,

        // 只有游客才能访问，在 register 和 login 请求中使用，只有未登录用户才能访问这些页面
        'guest' => AppHttpMiddlewareRedirectIfAuthenticated::class,

        // 访问节流，类似于 『1 分钟只能请求 10 次』的需求，一般在 API 中使用
        'throttle' => IlluminateRoutingMiddlewareThrottleRequests::class,
    ];
}

2. 请求实例化

以处理 Http 请求为例

index.php 入口文件

$response = $kernel->handle(
    $request = IlluminateHttpRequest::capture()
);

请求是通过 IlluminateHttpRequest::capture() 实例化的, 主要是将请求信息以对象形式表现出来

3. 请求处理

入口文件:

$response = $kernel->handle(
    $request = IlluminateHttpRequest::capture()
);

$kernel->handle(...) 处理请求过程

IlluminateFoundationHttpKernel

public function handle($request)
{
    try {
        $request->enableHttpMethodParameterOverride();

        $response = $this->sendRequestThroughRouter($request);
    } catch (Exception $e) {
        $this->reportException($e);

        $response = $this->renderException($request, $e);
    } catch (Throwable $e) {
        $this->reportException($e = new FatalThrowableError($e));

        $response = $this->renderException($request, $e);
    }

    $this->app['events']->dispatch(
        new EventsRequestHandled($request, $response)
    );

    return $response;
}


protected function sendRequestThroughRouter($request)
{
    $this->app->instance('request', $request);

    Facade::clearResolvedInstance('request');

    $this->bootstrap();		# 核心类初始化

    return (new Pipeline($this->app))
        ->send($request)
        ->through($this->app->shouldSkipMiddleware() ? [] : $this->middleware)
        ->then($this->dispatchToRouter());
}


protected function dispatchToRouter()
{
    return function ($request) {
        $this->app->instance('request', $request);

        return $this->router->dispatch($request);
    };
}

实际处理请求逻辑主要在 sendRequestThroughRouter 方法中, 它主要做了:

• 核心类的初始化

• 经由中间件过滤后将请求最终交由 Router 处理

  对于 Http 请求处理, 中间件包括:

  protected $middleware = [
  
      IlluminateFoundationHttpMiddlewareCheckForMaintenanceMode::class,
  
      IlluminateFoundationHttpMiddlewareValidatePostSize::class,
  
      AppHttpMiddlewareTrimStrings::class,
  
      IlluminateFoundationHttpMiddlewareConvertEmptyStringsToNull::class,
  
      AppHttpMiddlewareTrustProxies::class,
  
  ];
  
  

  该中间件数组定义在 Http 核心类中, 同时在核心类的构造函数中传递给 Router 类

3.1 请求处理环境初始化

核心类的初始化 bootstrap()

protected $bootstrappers = [
    IlluminateFoundationBootstrapLoadEnvironmentVariables::class,
    IlluminateFoundationBootstrapLoadConfiguration::class,
    IlluminateFoundationBootstrapHandleExceptions::class,
    IlluminateFoundationBootstrapRegisterFacades::class,
    IlluminateFoundationBootstrapRegisterProviders::class,
    IlluminateFoundationBootstrapBootProviders::class,
];

# 初始化
public function bootstrap()
{
    if (! $this->app->hasBeenBootstrapped()) {
        $this->app->bootstrapWith($this->bootstrappers());
    }
}

protected function bootstrappers()
{
    return $this->bootstrappers;
}

在服务容器 Application 类中

public function bootstrapWith(array $bootstrappers)
{
    $this->hasBeenBootstrapped = true;

    foreach ($bootstrappers as $bootstrapper) {
        $this['events']->fire('bootstrapping: '.$bootstrapper, [$this]);

        $this->make($bootstrapper)->bootstrap($this);

        $this['events']->fire('bootstrapped: '.$bootstrapper, [$this]);
    }
}

该步骤主要是主要是对核心类中定义的 $bootstrappers 数组元素(引导类)初始化.

bootstrap 过程具体是在服务容器来中进行, 由核心类调用并传入待初始化的类

Http 核心类默认包含以下 6 个启动服务:

1. 环境监测 IlluminateFoundationBootstrapLoadEnvironmentVariables::class

从 .env 文件中解析环境变量到 getevn(), $_ENV, $_SERVER

依赖 vlucas/phpdotenv 扩展包

2. 配置加载 IlluminateFoundationBootstrapLoadConfiguration::class

载入 config 目录下所有 php 配置文件, 并将生成的配置存储类绑定到服务容器 $app['config']

同时配置时区及 多字节格式(utf8)

3. 常处理 IlluminateFoundationBootstrapHandleExceptions::class

报告所有错误 error_report(E_ALL)

提供对未捕获的异常, 错误的全局处理 set_error_handler, set_exception_handler, register_shutdown_function

4. 外观注册 IlluminateFoundationBootstrapRegisterFacades::class

从 app.aliases 中读取外观配置数组

'aliases' => [

        'App' => IlluminateSupportFacadesApp::class,
        'Artisan' => IlluminateSupportFacadesArtisan::class,
        'Auth' => IlluminateSupportFacadesAuth::class,
        'Blade' => IlluminateSupportFacadesBlade::class,
        'Broadcast' => IlluminateSupportFacadesBroadcast::class,
        'Bus' => IlluminateSupportFacadesBus::class,
        'Cache' => IlluminateSupportFacadesCache::class,
        'Config' => IlluminateSupportFacadesConfig::class,
        'Cookie' => IlluminateSupportFacadesCookie::class,
        'Crypt' => IlluminateSupportFacadesCrypt::class,
        'DB' => IlluminateSupportFacadesDB::class,
        'Eloquent' => IlluminateDatabaseEloquentModel::class,
        'Event' => IlluminateSupportFacadesEvent::class,
        'File' => IlluminateSupportFacadesFile::class,
        'Gate' => IlluminateSupportFacadesGate::class,
        'Hash' => IlluminateSupportFacadesHash::class,
        'Lang' => IlluminateSupportFacadesLang::class,
        'Log' => IlluminateSupportFacadesLog::class,
        'Mail' => IlluminateSupportFacadesMail::class,
        'Notification' => IlluminateSupportFacadesNotification::class,
        'Password' => IlluminateSupportFacadesPassword::class,
        'Queue' => IlluminateSupportFacadesQueue::class,
        'Redirect' => IlluminateSupportFacadesRedirect::class,
        'Redis' => IlluminateSupportFacadesRedis::class,
        'Request' => IlluminateSupportFacadesRequest::class,
        'Response' => IlluminateSupportFacadesResponse::class,
        'Route' => IlluminateSupportFacadesRoute::class,
        'Schema' => IlluminateSupportFacadesSchema::class,
        'Session' => IlluminateSupportFacadesSession::class,
        'Storage' => IlluminateSupportFacadesStorage::class,
        'URL' => IlluminateSupportFacadesURL::class,
        'Validator' => IlluminateSupportFacadesValidator::class,
        'View' => IlluminateSupportFacadesView::class,

    ],

使用 spl_autoload_register(...) 处理类加载, 配合 class_alias() 提供类的别名调用

Facade外观类基类依赖__callStatic` 调用方法( 使用服务容器实例化对应类)

5. 服务提供者注册 IlluminateFoundationBootstrapRegisterProviders::class

从 app.providers 中读取所有服务提供者

'providers' => [

        /*
         * Laravel Framework Service Providers...
         */
        IlluminateAuthAuthServiceProvider::class,
        IlluminateBroadcastingBroadcastServiceProvider::class,
        IlluminateBusBusServiceProvider::class,
        IlluminateCacheCacheServiceProvider::class,
        IlluminateFoundationProvidersConsoleSupportServiceProvider::class,
        IlluminateCookieCookieServiceProvider::class,
        IlluminateDatabaseDatabaseServiceProvider::class,
        IlluminateEncryptionEncryptionServiceProvider::class,
        IlluminateFilesystemFilesystemServiceProvider::class,
        IlluminateFoundationProvidersFoundationServiceProvider::class,
        IlluminateHashingHashServiceProvider::class,
        IlluminateMailMailServiceProvider::class,
        IlluminateNotificationsNotificationServiceProvider::class,
        IlluminatePaginationPaginationServiceProvider::class,
        IlluminatePipelinePipelineServiceProvider::class,
        IlluminateQueueQueueServiceProvider::class,
        IlluminateRedisRedisServiceProvider::class,
        IlluminateAuthPasswordsPasswordResetServiceProvider::class,
        IlluminateSessionSessionServiceProvider::class,
        IlluminateTranslationTranslationServiceProvider::class,
        IlluminateValidationValidationServiceProvider::class,
        IlluminateViewViewServiceProvider::class,

        /*
         * Package Service Providers...
         */

        /*
         * Application Service Providers...
         */
        AppProvidersAppServiceProvider::class,
        AppProvidersAuthServiceProvider::class,
        // AppProvidersBroadcastServiceProvider::class,
        AppProvidersEventServiceProvider::class,
        AppProvidersRouteServiceProvider::class,	# 路由表生成
    ],

服务提供者经过解析后分为 3 种类型的服务提供者:

• eager 类型

  马上调用 register 注册

• deferred 类型

  记录下来, 当服务容器解析对应服务时, 才注册对应的服务提供者

• when 类型

  记录下来, 当对应 event 触发时在注册对应服务提供者

6. 启动提供者 IlluminateFoundationBootstrapBootProviders::class

调用服务容器的 boot() 方法, 依次调用在服务容器中 register 的所有服务提供者的 boot() 方法

3.2 路由处理请求

在内核处理请求, 将请求实例通过中间件处理后, 将请求的处理交给路由 Router 进行控制器的分发.

Http Kernel

protected function dispatchToRouter()
{
    return function ($request) {
        $this->app->instance('request', $request);

        return $this->router->dispatch($request);
    };
}

路由表存储结构说明

IlluminateRoutingRoute 存储单条路由

IlluminateRoutingRouteCollection 保存所有 Route 实例, 形成路由表

IlluminateRoutingRouter 类实例持有 RouteCollection 路由表实例.

即, 一个 Router 持有一个 RouteCollection, 而 RouteCollection 拥有 N 个 Route

在 Router 中对请求的处理同样经过一系列的 路由中间件

# 路由处理请求的入库
public function dispatchToRoute(Request $request)
{
    return $this->runRoute($request, $this->findRoute($request));
}

# 根据请求的 url 和 method 查找对应的 route
protected function findRoute($request)
{
    $this->current = $route = $this->routes->match($request);

    $this->container->instance(Route::class, $route);

    return $route;
}

# 根据对应的请求和路由条目, 返回相应的 $response
protected function runRoute(Request $request, Route $route)
{
    $request->setRouteResolver(function () use ($route) {
        return $route;
    });

    $this->events->dispatch(new EventsRouteMatched($route, $request));

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

# 请求经过路由中间件过滤后, 交由 route 的 run() 方法处理
protected function runRouteWithinStack(Route $route, Request $request)
{
    $shouldSkipMiddleware = $this->container->bound('middleware.disable') &&
        $this->container->make('middleware.disable') === true;

    $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()
            );
        });
}

route 的 run() 方法最终将请求转给 IlluminateRoutingControllerDispatcher::dispatch 处理

public function dispatch(Route $route, $controller, $method)
{
    $parameters = $this->resolveClassMethodDependencies(
    	$route->parametersWithoutNulls(), $controller, $method
    );

    if (method_exists($controller, 'callAction')) {
   	 	return $controller->callAction($method, $parameters);
    }

    return $controller->{$method}(...array_values($parameters));
}

剩下的事情就是 Controller控制器 的事了.

3.3 处理返回的 Response

在 Router 中有一个方法, 用于对返回的 $response 进行处理

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

/**
* @return IlluminateHttpResponse|IlluminateHttpJsonResponse
*/
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);	# 最后的处理
}  

上述过程中, 在返回 $response 之前进行了最后的处理 $response->prepare($request)

该过程是在 SymfonyComponentHttpFoundationResponse::prepare() 中进行

对响应的封装是通过 IlluminateHttpResponse 类完成, 该类底层是 Symfony 框架的 Response 类

即, SymfonyComponentHttpFoundationResponse

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;
}

4. 响应发送和程序终止

4.1 响应的发送

在 index.php 入口文件的最后是将响应返回给客户端

$response->send();

SymfonyComponentHttpFoundationResponse

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 sendHeaders()
{
    // headers have already been sent by the developer
    if (headers_sent()) {
        return $this;
    }

    // headers
    foreach ($this->headers->allPreserveCase() 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);

    return $this;
}

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

    return $this;
}

4.2 请求中止

在 index.php 入口文件的最后:

$kernel->terminate($request, $response);

依旧以 Http Kernel 为例:

public function terminate($request, $response)
{
    $this->terminateMiddleware($request, $response);	# 中间件中止处理

    $this->app->terminate();	# 服务容器的中止处理函数
}

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);
        }
    }
}

此处的中间件指的是定义在 Kernel 中的 $middleware 中间件数组列表, 不包含 路由中间件.

Laravel 5.1 注: 默认只有会话中间件包含 terminate() 函数

Application 服务容器的中止处理函数

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