對於Laravel框架的生命週期與原理分析

這篇文章主要介紹了Laravel框架生命週期與原理,結合實例形式總結分析了Laravel框架針對用戶請求響應的完整運行週期、流程、原理,需要的朋友可以參考下

本文實例講述了Laravel框架生命週期與原理。分享給大家供大家參考，具體如下：

#引言：

#如果你對一件工具的使用原理瞭如指掌，那麼你在用這件工具的時候會充滿信心！

正文：

一旦使用者（瀏覽器）發送了一個HTTP請求，我們的apache或nginx一般都會轉到index.php ，因此，之後的一系列步驟都是從index.php開始的，我們先來看看這個檔案程式碼。

<?php
require __DIR__.&#39;/../bootstrap/autoload.php&#39;;
$app = require_once __DIR__.&#39;/../bootstrap/app.php&#39;;
/*
|--------------------------------------------------------------------------
| 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&#39;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);

作者在註解裡談了kernel的作用，kernel的作用，kernel處理來訪的請求，並且發送相應返回給用戶瀏覽器。

這裡又牽涉到了一個app對象，所以附上app對象，所以附上app對象的源碼，這份源碼是\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__.&#39;/../&#39;)
);
/*
|--------------------------------------------------------------------------
| 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;

請看app變數是Illuminate\Foundation\Application類別的對象，所以呼叫了這個類別的建構函數，具體做了什麼事，我們看源碼。

public function __construct($basePath = null)
{
  if ($basePath) {
    $this->setBasePath($basePath);
  }
  $this->registerBaseBindings();
  $this->registerBaseServiceProviders();
  $this->registerCoreContainerAliases();
}

建構器做了3件事，前兩件事很好理解，創建Container，註冊了ServiceProvider，看程式碼

/**
 * 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));
}

最後一件事，是做了一個很大的數組，定義了大量的別名，側面體現程式設計師是聰明的懶人。

/**
 * 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);
    }
  }
}

這裡出現了一個instance函數，其實這並不是Application類別的函數，而是Application類別的父類別Container類別的函數

/**
 * 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的子類，所以$app不僅是Application類別的對象，還是Container的對象，所以，新出現的singleton函數我們就可以到Container類別的原始碼檔案裡查。 bind函數和singleton的差別請見這篇文章。

singleton這個函數，前一個參數是實際類別名，後者參數是類別的「別名」。

$app物件宣告了3個單例模型對象，分別是HttpKernel，ConsoleKernel，ExceptionHandler。請注意，這裡並沒有創建對象，只是聲明，也只是起了一個「別名」。

大家有沒有發現，index.php中也有一個$kernel變量，但是只保存了make出來的HttpKernel變量，因此本文不再討論，ConsoleKernel，ExceptionHandler。 。 。

繼續在資料夾下找到App\Http\Kernel.php，既然我們把實際的HttpKernel做的事情都寫在這個php檔案裡，就從這份程式碼裡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&#39;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&#39;s route middleware groups.
   *
   * @var array
   */
  protected $middlewareGroups = [
    &#39;web&#39; => [
      \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,
    ],
    &#39;api&#39; => [
      &#39;throttle:60,1&#39;,
    ],
  ];
  /**
   * The application&#39;s route middleware.
   *
   * These middleware may be assigned to groups or used inpidually.
   *
   * @var array
   */
  protected $routeMiddleware = [
    &#39;auth&#39; => \App\Http\Middleware\Authenticate::class,
    &#39;auth.basic&#39; => \Illuminate\Auth\Middleware\AuthenticateWithBasicAuth::class,
    &#39;guest&#39; => \App\Http\Middleware\RedirectIfAuthenticated::class,
    &#39;throttle&#39; => \Illuminate\Routing\Middleware\ThrottleRequests::class,
  &#39;mymiddleware&#39;=>\App\Http\Middleware\MyMiddleware::class,
  ];
}

一目了然，HttpKernel裡定義了中間件陣列。

該做的做完了，就開始了請求到回應的過程，見index.php

#

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

最後在中止，釋放所有資源。

/**
* 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();
}

總結一下，簡單歸納整個過程就是：

1.index.php載入\ bootstrap\app.php，在Application類別的建構子中建立Container，註冊了ServiceProvider，定義了別名數組，然後用app變數保存建構子建構出來的物件。

2.使用app這個對象，建立1個單例模式的物件HttpKernel，在建立HttpKernel時呼叫了建構函數，完成了中間件的宣告。

3.以上這些工作都是在請求來訪之前完成的，接下來開始等待請求，然後就是：接受到請求-->處理請求 -->發送回應-->中止app變數

#以上就是本文的全部內容，希望對大家的學習有所幫助，更相關內容請關注PHP中文網！

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