本文實(shí)例講述了Laravel框架生命周期與原理。分享給大家供大家參考，具體如下：
引言：
如果你對(duì)一件工具的使用原理了如指掌，那么你在用這件工具的時(shí)候會(huì)充滿信心！
正文：
一旦用戶（瀏覽器）發(fā)送了一個(gè)HTTP請(qǐng)求，我們的apache或者nginx一般都轉(zhuǎn)到index.php，因此，之后的一系列步驟都是從index.php開始的，我們先來看一看這個(gè)文件代碼。
<?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);
作者在注釋里談了kernel的作用，kernel的作用，kernel處理來訪的請(qǐng)求，并且發(fā)送相應(yīng)返回給用戶瀏覽器。
這里又涉及到了一個(gè)app對(duì)象，所以附上app對(duì)象，所以附上app對(duì)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__.'/../') ); /* |-------------------------------------------------------------------------- | 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 $app;
請(qǐng)看app變量是Illuminate\Foundation\Application類的對(duì)象，所以調(diào)用了這個(gè)類的構(gòu)造函數(shù)，具體做了什么事，我們看源碼。
public function __construct($basePath = null)
{
if ($basePath) {
$this->setBasePath($basePath);
}
$this->registerBaseBindings();
$this->registerBaseServiceProviders();
$this->registerCoreContainerAliases();
}
構(gòu)造器做了3件事，前兩件事很好理解，創(chuàng)建Container，注冊(cè)了ServiceProvider，看代碼
/**
* Register the basic bindings into the container.
*
* @return void
*/
protected function registerBaseBindings()
{
static::setInstance($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));
}
最后一件事，是做了個(gè)很大的數(shù)組，定義了大量的別名，側(cè)面體現(xiàn)程序員是聰明的懶人。
/**
* 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);
}
}
}
這里出現(xiàn)了一個(gè)instance函數(shù)，其實(shí)這并不是Application類的函數(shù)，而是Application類的父類Container類的函數(shù)
/**
* 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類的對(duì)象，還是Container的對(duì)象，所以，新出現(xiàn)的singleton函數(shù)我們就可以到Container類的源代碼文件里查。bind函數(shù)和singleton的區(qū)別見這篇博文。
singleton這個(gè)函數(shù)，前一個(gè)參數(shù)是實(shí)際類名，后一個(gè)參數(shù)是類的“別名”。
$app對(duì)象聲明了3個(gè)單例模型對(duì)象，分別是HttpKernel，ConsoleKernel，ExceptionHandler。請(qǐng)注意，這里并沒有創(chuàng)建對(duì)象，只是聲明，也只是起了一個(gè)“別名”。
大家有沒有發(fā)現(xiàn)，index.php中也有一個(gè)$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(xù)在文件夾下找到App\Http\Kernel.php，既然我們把實(shí)際的HttpKernel做的事情都寫在這個(gè)php文件里，就從這份代碼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里定義了中間件數(shù)組。
該做的做完了，就開始了請(qǐng)求到響應(yīng)的過程，見index.php
$response = $kernel->handle( $request = Illuminate\Http\Request::capture() ); $response->send();
最后在中止，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(jié)一下，簡單歸納整個(gè)過程就是：
1.index.php加載\bootstrap\app.php，在Application類的構(gòu)造函數(shù)中創(chuàng)建Container，注冊(cè)了ServiceProvider，定義了別名數(shù)組，然后用app變量保存構(gòu)造函數(shù)構(gòu)造出來的對(duì)象。
2.使用app這個(gè)對(duì)象，創(chuàng)建1個(gè)單例模式的對(duì)象HttpKernel，在創(chuàng)建HttpKernel時(shí)調(diào)用了構(gòu)造函數(shù)，完成了中間件的聲明。
3.以上這些工作都是在請(qǐng)求來訪之前完成的，接下來開始等待請(qǐng)求，然后就是：接受到請(qǐng)求-->處理請(qǐng)求-->發(fā)送響應(yīng)-->中止app變量
希望本文所述對(duì)大家基于Laravel框架的PHP程序設(shè)計(jì)有所幫助。
