Laravel框架生命周期与原理分析
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。
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
singleton( Illuminate\Contracts\Http\Kernel::class, App\Http\Kernel::class ); $app->singleton( Illuminate\Contracts\Console\Kernel::class, App\Console\Kernel::class ); $app->singleton( Illuminate\Contracts\Debug\ExceptionHandler::class, App\Exceptions\Handler::class ); /* |-------------------------------------------------------------------------- |ReturnTheApplication |-------------------------------------------------------------------------- | |Thisscriptreturnstheapplicationinstance.Theinstanceisgivento |thecallingscriptsowecanseparatethebuildingoftheinstances |fromtheactualrunningoftheapplicationandsendingresponses. | */ return$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。
publicfunction__construct($basePath=null)
{
if($basePath){
$this->setBasePath($basePath);
}
$this->registerBaseBindings();
$this->registerBaseServiceProviders();
$this->registerCoreContainerAliases();
}
构造器做了3件事，前两件事很好理解，创建Container，注册了ServiceProvider，看代码
/**
*Registerthebasicbindingsintothecontainer.
*
*@returnvoid
*/
protectedfunctionregisterBaseBindings()
{
static::setInstance($this);
$this->instance('app',$this);
$this->instance(Container::class,$this);
}
/**
*Registerallofthebaseserviceproviders.
*
*@returnvoid
*/
protectedfunctionregisterBaseServiceProviders()
{
$this->register(newEventServiceProvider($this));
$this->register(newLogServiceProvider($this));
$this->register(newRoutingServiceProvider($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。
/**
*Registerthecoreclassaliasesinthecontainer.
*
*@returnvoid
*/
publicfunctionregisterCoreContainerAliases()
{
$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($aliasesas$key=>$aliases){
foreach($aliasesas$alias){
$this->alias($key,$alias);
}
}
}
这里出现了一个instance函数，其实这并不是Application类的函数，而是Application类的父类Container类的函数
/**
*Registeranexistinginstanceassharedinthecontainer.
*
*@paramstring$abstract
*@parammixed$instance
*@returnvoid
*/
publicfunctioninstance($abstract,$instance)
{
$this->removeAbstractAlias($abstract);
unset($this->aliases[$abstract]);
//We'llchecktodetermineifthistypehasbeenboundbefore,andifithas
//wewillfirethereboundcallbacksregisteredwiththecontainerandit
//canbeupdatedwithconsumingclassesthathavegottenresolvedhere.
$this->instances[$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singleton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。
singleton这个函数，前一个参数是实际类名，后一个参数是类的“别名”。
$app对象声明了3个单例模型对象，分别是HttpKernel，ConsoleKernel，ExceptionHandler。请注意，这里并没有创建对象，只是声明，也只是起了一个“别名”。
大家有没有发现，index.php中也有一个$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App\Http\Kernel.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？
[ \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', ], ]; /** *Theapplication'sroutemiddleware. * *Thesemiddlewaremaybeassignedtogroupsorusedindividually. * *@vararray */ 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
$response=$kernel->handle( $request=Illuminate\Http\Request::capture() ); $response->send();
最后在中止，释放所有资源。
/**
*Calltheterminatemethodonanyterminablemiddleware.
*
*@param\Illuminate\Http\Request$request
*@param\Illuminate\Http\Response$response
*@returnvoid
*/
publicfunctionterminate($request,$response)
{
$this->terminateMiddleware($request,$response);
$this->app->terminate();
}
总结一下，简单归纳整个过程就是：
1.index.php加载\bootstrap\app.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：接受到请求-->处理请求-->发送响应-->中止app变量
更多关于Laravel相关内容感兴趣的读者可查看本站专题：《Laravel框架入门与进阶教程》、《php优秀开发框架总结》、《php面向对象程序设计入门教程》、《php+mysql数据库操作入门教程》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。
声明：本文内容来源于网络，版权归原作者所有，内容由互联网用户自发贡献自行上传，本网站不拥有所有权，未作人工编辑处理，也不承担相关法律责任。如果您发现有涉嫌版权的内容，欢迎发送邮件至：czq8825#qq.com（发邮件时，请将#更换为@）进行举报，并提供相关证据，一经查实，本站将立刻删除涉嫌侵权内容。