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    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。

    ?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

    /**
     * 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?

    ?php
    namespace 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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