本文实例讲述了Laravel框架生命周期与原理。分享给大家供大家参考，具体如下：
引言：
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;">
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PHP
PHP;">
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 $app;
请看app变量是调用了这个类的构造函数，具体做了什么事，我们看源码。
setBasePath($basePath);
}
$this->registerBaseBindings();
$this->registerBaseServiceProviders();
$this->registerCoreContainerAliases();
}
构造器做了3件事，前两件事很好理解，创建Container，注册了ServiceProvider，看代码
instance('app',$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。
[\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,$alias);
}
}
}
这里出现了一个instance函数，其实这并不是Application类的函数，而是Application类的父类Container类的函数
removeAbstractAlias($abstract);
unset($this->aliases[$abstract]);
// We'll check to determine if this type has been bound before,and if it has
// we will fire the rebound callbacks registered with the container and it
// can be updated with consuming classes that have gotten resolved here.
$this->instances[$abstract] = $instance;
if ($this->bound($abstract)) {
$this->rebound($abstract);
}
}
Application是Container的子类，所以$app不仅是Application类的对象，还是Container的对象，所以，新出现的函数我们就可以到Container类的源代码文件里查。bind函数和singleton的区别见这篇博文。
函数，前一个参数是实际类名，后一个参数是类的“别名”。
$app对象声明了3个单例模型对象，分别是
大家有没有发现，index.PHP中也有一个$kernel变量，但是只保存了make出来的HttpKernel变量，因此本文不再讨论，ConsoleKernel，ExceptionHandler。。。
继续在文件夹下找到PHP，既然我们把实际的HttpKernel做的事情都写在这个PHP文件里，就从这份代码里看看究竟做了哪些事？
PHP;">
[
\App\Http\Middleware\EncryptCookies::class,\Illuminate\Cookie\Middleware\AddQueuedCookiesToResponse::class,\Illuminate\Session\Middleware\StartSession::class,\Illuminate\View\Middleware\ShareErrorsFromSession::class,\App\Http\Middleware\VerifyCsrfToken::class,],'api' => [
'throttle:60,1',];
/**
* The application's route middleware.
*
* These middleware may be assigned to groups or used individually.
*
* @var array
*/
protected $routeMiddleware = [
'auth' => \App\Http\Middleware\Authenticate::class,'auth.basic' => \Illuminate\Auth\Middleware\AuthenticateWithBasicAuth::class,'guest' => \App\Http\Middleware\RedirectIfAuthenticated::class,'throttle' => \Illuminate\Routing\Middleware\ThrottleRequests::class,'mymiddleware'=>\App\Http\Middleware\MyMiddleware::class,];
}
一目了然，HttpKernel里定义了中间件数组。
该做的做完了，就开始了请求到响应的过程，见index.PHP
handle(
$request = Illuminate\Http\Request::capture()
);
$response->send();
最后在中止，释放所有资源。
terminateMiddleware($request,$response);
$this->app->terminate();
}
总结一下，简单归纳整个过程就是：
1.index.PHP加载PHP，在Application类的构造函数中创建Container，注册了ServiceProvider，定义了别名数组，然后用app变量保存构造函数构造出来的对象。
2.使用app这个对象，创建1个单例模式的对象HttpKernel，在创建HttpKernel时调用了构造函数，完成了中间件的声明。
3.以上这些工作都是在请求来访之前完成的，接下来开始等待请求，然后就是：
更多关于Laravel相关内容感兴趣的读者可查看本站专题：《》、《》、《》、《》及《PHP常见数据库操作技巧汇总》
希望本文所述对大家基于Laravel框架的PHP程序设计有所帮助。
