如果你对一件工具的使用原理了如指掌，那么你在用这件工具的时候会充满信心！
正文：
一旦用户（浏览器）发送了一个HTTP请求，我们的apache或者nginx一般都转到index.php，因此，之后的一系列步骤都是从index.php开始的，我们先来看一看这个文件代码。
<?php require __DIR__.'/../bootstrap/autoload.php'; $app = require_once __DIR__.'/../bootstrap/app.php'; /* |-------------------------------------------------------------------------- | Run The Application |-------------------------------------------------------------------------- | | Once we have the application, we can handle the incoming request | through the kernel, and send the associated response back to | the client's browser allowing them to enjoy the creative | and wonderful application we have prepared for them. | */ $kernel = $app->make(Illuminate\Contracts\Http\Kernel::class); $response = $kernel->handle( $request = Illuminate\Http\Request::capture() ); $response->send(); $kernel->terminate($request, $response);
作者在注释里谈了kernel的作用，kernel的作用，kernel处理来访的请求，并且发送相应返回给用户浏览器。
这里又涉及到了一个app对象，所以附上app对象，所以附上app对象的源码，这份源码是\bootstrap\app.php
<?php /* |-------------------------------------------------------------------------- | Create The Application |-------------------------------------------------------------------------- | | The first thing we will do is create a new Laravel application instance | which serves as the "glue" for all the components of Laravel, and is | the IoC container for the system binding all of the various parts. | */ $app = new Illuminate\Foundation\Application( realpath(__DIR__.'/../') ); /* |-------------------------------------------------------------------------- | Bind Important Interfaces |-------------------------------------------------------------------------- | | Next, we need to bind some important interfaces into the container so | we will be able to resolve them when needed. The kernels serve the | incoming requests to this application from both the web and CLI. | */ $app->singleton( Illuminate\Contracts\Http\Kernel::class, App\Http\Kernel::class ); $app->singleton( Illuminate\Contracts\Console\Kernel::class, App\Console\Kernel::class ); $app->singleton( Illuminate\Contracts\Debug\ExceptionHandler::class, App\Exceptions\Handler::class ); /* |-------------------------------------------------------------------------- | Return The Application |-------------------------------------------------------------------------- | | This script returns the application instance. The instance is given to | the calling script so we can separate the building of the instances | from the actual running of the application and sending responses. | */ return $app;
请看app变量是Illuminate\Foundation\Application类的对象，所以调用了这个类的构造函数，具体做了什么事，我们看源码。
public function __construct($basePath = null) { if ($basePath) { $this->setBasePath($basePath); } $this->registerBaseBindings(); $this->registerBaseServiceProviders(); $this->registerCoreContainerAliases(); }
构造器做了3件事，前两件事很好理解，创建Container，注册了ServiceProvider，看代码
/** * Register the basic bindings into the container. * * @return void */ protected function registerBaseBindings() { static::setInstance($this); $this->instance('app', $this); $this->instance(Container::class, $this); } /** * Register all of the base service providers. * * @return void */ protected function registerBaseServiceProviders() { $this->register(new EventServiceProvider($this)); $this->register(new LogServiceProvider($this)); $this->register(new RoutingServiceProvider($this)); }
最后一件事，是做了个很大的数组，定义了大量的别名，侧面体现程序员是聪明的懒人。
/** * Register the core class aliases in the container. * * @return void */ public function registerCoreContainerAliases() { $aliases = [ 'app' => [\Illuminate\Foundation\Application::class, \Illuminate\Contracts\Container\Container::class, \Illuminate\Contracts\Foundation\Application::class], 'auth' => [\Illuminate\Auth\AuthManager::class, \Illuminate\Contracts\Auth\Factory::class], 'auth.driver' => [\Illuminate\Contracts\Auth\Guard::class], 'blade.compiler' => [\Illuminate\View\Compilers\BladeCompiler::class], 'cache' => [\Illuminate\Cache\CacheManager::class, \Illuminate\Contracts\Cache\Factory::class], 'cache.store' => [\Illuminate\Cache\Repository::class, \Illuminate\Contracts\Cache\Repository::class], 'config' => [\Illuminate\Config\Repository::class, \Illuminate\Contracts\Config\Repository::class], 'cookie' => [\Illuminate\Cookie\CookieJar::class, \Illuminate\Contracts\Cookie\Factory::class, \Illuminate\Contracts\Cookie\QueueingFactory::class], 'encrypter' => [\Illuminate\Encryption\Encrypter::class, \Illuminate\Contracts\Encryption\Encrypter::class], 'db' => [\Illuminate\Database\DatabaseManager::class], 'db.connection' => [\Illuminate\Database\Connection::class, \Illuminate\Database\ConnectionInterface::class], 'events' => [\Illuminate\Events\Dispatcher::class, \Illuminate\Contracts\Events\Dispatcher::class], 'files' => [\Illuminate\Filesystem\Filesystem::class], 'filesystem' => [\Illuminate\Filesystem\FilesystemManager::class, \Illuminate\Contracts\Filesystem\Factory::class], 'filesystem.disk' => [\Illuminate\Contracts\Filesystem\Filesystem::class], 'filesystem.cloud' => [\Illuminate\Contracts\Filesystem\Cloud::class], 'hash' => [\Illuminate\Contracts\Hashing\Hasher::class], 'translator' => [\Illuminate\Translation\Translator::class, \Illuminate\Contracts\Translation\Translator::class], 'log' => [\Illuminate\Log\Writer::class, \Illuminate\Contracts\Logging\Log::class, \Psr\Log\LoggerInterface::class], 'mailer' => [\Illuminate\Mail\Mailer::class, \Illuminate\Contracts\Mail\Mailer::class, \Illuminate\Contracts\Mail\MailQueue::class], 'auth.password' => [\Illuminate\Auth\Passwords\PasswordBrokerManager::class, \Illuminate\Contracts\Auth\PasswordBrokerFactory::class], 'auth.password.broker' => [\Illuminate\Auth\Passwords\PasswordBroker::class, \Illuminate\Contracts\Auth\PasswordBroker::class], 'queue' => [\Illuminate\Queue\QueueManager::class, \Illuminate\Contracts\Queue\Factory::class, \Illuminate\Contracts\Queue\Monitor::class], 'queue.connection' => [\Illuminate\Contracts\Queue\Queue::class], 'queue.failer' => [\Illuminate\Queue\Failed\FailedJobProviderInterface::class], 'redirect' => [\Illuminate\Routing\Redirector::class], 'redis' => [\Illuminate\Redis\RedisManager::class, \Illuminate\Contracts\Redis\Factory::class], 'request' => [\Illuminate\Http\Request::class, \Symfony\Component\HttpFoundation\Request::class], 'router' => [\Illuminate\Routing\Router::class, \Illuminate\Contracts\Routing\Registrar::class, \Illuminate\Contracts\Routing\BindingRegistrar::class], 'session' => [\Illuminate\Session\SessionManager::class], 'session.store' => [\Illuminate\Session\Store::class, \Illuminate\Contracts\Session\Session::class], 'url' => [\Illuminate\Routing\UrlGenerator::class, \Illuminate\Contracts\Routing\UrlGenerator::class], 'validator' => [\Illuminate\Validation\Factory::class, \Illuminate\Contracts\Validation\Factory::class], 'view' => [\Illuminate\View\Factory::class, \Illuminate\Contracts\View\Factory::class], ]; foreach ($aliases as $key => $aliases) { foreach ($aliases as $alias) { $this->alias($key, $alias); } } }
这里出现了一个instance函数，其实这并不是Application类的函数，而是Application类的父类Container类的函数