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Laravel框架生命周期与原理分析

2019-11-21 20:25:35
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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。

<?phprequire __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

/** * Register an existing instance as shared in the container. * * @param string $abstract * @param mixed  $instance * @return void */public function instance($abstract, $instance){  $this->removeAbstractAlias($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HttpKernelConsoleKernelExceptionHandler。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?

<?phpnamespace App/Http;use Illuminate/Foundation/Http/Kernel as HttpKernel;class Kernel extends HttpKernel{  /**   * The application's global HTTP middleware stack.   *   * These middleware are run during every request to your application.   *   * @var array   */  protected $middleware = [    /Illuminate/Foundation/Http/Middleware/CheckForMaintenanceMode::class,    ///App/Http/Middleware/MyMiddleware::class,  ];  /**   * The application's route middleware groups.   *   * @var array   */  protected $middlewareGroups = [    'web' => [      /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

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

最后在中止,释放所有资源。

/*** Call the terminate method on any terminable middleware.** @param /Illuminate/Http/Request $request* @param /Illuminate/Http/Response $response* @return void*/public function terminate($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。

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