Laravel生命周期与原理

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';$app = require_once __dir__.'/../bootstrap/app.php';/*|--------------------------------------------------------------------------| run the application|--------------------------------------------------------------------------|| once we have the application, we can handle the incoming request| through the kernel, and nd the associated respon back to| the client's browr allowing them to enjoy the creative| and wonderful application we have prepared for them.|*/$kernel = $app->make(illuminate\contracts\http\kernel::class);$respon = $kernel->handle(  $request = illuminate\http\request::capture());$respon->nd();$kernel->terminate($request, $respon);

这里在注释里谈了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对象的源码，这份源码是\bootstrap\app.php

 1 <?php 2 /* 3 |-------------------------------------------------------------------------- 4 | create the application 5 |-------------------------------------------------------------------------- 6 | 7 | the first thing we will do is create a new laravel application instance 8 | which rves as the "glue" for all the components of laravel, and is 9 | the ioc container for the system binding all of the various parts.10 |11 */12 $app = new illuminate\foundation\application(13   realpath(__dir__.'/../')14 );15 /*16 |--------------------------------------------------------------------------17 | bind important interfaces18 |--------------------------------------------------------------------------19 |20 | next, we need to bind some important interfaces into the container so21 | we will be able to resolve them when needed. the kernels rve the22 | incoming requests to this application from both the web and cli.23 |24 */25 $app->singleton(26   illuminate\contracts\http\kernel::class,27   app\http\kernel::class28 );29 $app->singleton(30   illuminate\cont韦庄racts\console\kernel::class,31   app\console\kernel::class32 );33 $app->singleton(34   illuminate\contracts\debug\exceptionhandler::class,35   app\exceptions\handler::class36 );37 /*38 |--------------------------------------------------------------------------39 | return the application40 |--------------------------------------------------------------------------41 |42 | this script returns the application instance. the instance is given to43 | the calling script so we can parate the building of the instances44 | from the actual running of the application and nding respons.45 |46 */47 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。

1 public function __construct($bapath = null)2 {3   if ($bapath) {4     $this->tbapath($bapath);5   }6   $this->registerbabindings();7   $this->registerbarviceproviders();8   $this->registercorecontaineralias();9 }

构造器做了3件事，前两件事很好理解，创建container，注册了rviceprovider，看代码

 1 /** 2  * register the basic bindings into the container. 3  * 4  * @return void 5  */ 6 protected function registerbabindings() 7 { 8   static::tinstance($this); 9   $this->instance('app', $this);10   $this->instance(container::class, $this);11 }12 /**13  * register all of the ba rvice providers.14  *15  * @return void16  */17 protected function registerbarviceproviders()18 {19   $this->register(new eventrviceprovider($this));20   $this->register(new logrviceprovider($this));21   $this->register(new routingrviceprovider($this));22 }

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。

 1 /** 2  * register the core class alias in the container. 3  * 4  * @return void 5  */ 6 public function registercorecontaineralias() 7 { 8   $alias = [ 9     'app'         => [\illuminate\foundation\application::class, \illuminate\contracts\container\container::class, \illuminate\contracts\foundation\application::class],10     'auth'         => [\illuminate\auth\authmanager::class, \illuminate\contracts\auth\factory::class],11     'auth.driver'     => [\illuminate\contracts\auth\guard::class],12     'blade.compiler'    => [\illuminate\view\compilers\bladecompiler::class],13     'cache'        => [\illuminate\cache\cachemanager::class, \illuminate\contracts\cache\factory::class],14     'cache.store'     => [\illuminate\cache\repository::class, \illuminate\contracts\cache\repository::class],15     'config'        => [\illuminate\config\repository::class, \illuminate\contracts\config\repository::class],16     'cookie'        => [\illuminate\cookie\cookiejar::class, \illuminate\contracts\cookie\factory::class, \illuminate\contracts\cookie\queueingfactory::class],17     'encrypter'      => [\illuminate\encryption\encrypter::class, \illuminate\contracts\encryption\encrypter::class],18     'db'          => [\illuminate\databa\databamanager::class],19     'db.connection'    => [\illuminate\databa\connection::class, \illuminate\databa\connectioninterface::class],20     'events'        => [\illuminate\events\dispatcher::class, \illuminate\contracts\events\dispatcher::class],21     'files'        => [\illuminate\filesystem\filesystem::class],22     'filesystem'      => [\illuminate\filesystem\filesystemmanager::class, \illuminate\contracts\filesystem\factory::class],23     'filesystem.disk'   => [\illuminate\contracts\filesystem\filesystem::class],24     'filesystem.cloud'   => [\illuminate\contracts\filesystem\cloud::class],25     'hash'         => [\illuminate\contracts\hashing\hasher::class],26     'translator'      => [\illuminate\translation\translator::class, \illuminate\contracts\translation\translator::class],27     'log'         => [\illuminate\log\writer::class, \illuminate\contracts\logging\log::class, \psr\log\loggerinterface::class],28     'mailer'        => [\illuminate\mail\mailer::class, \illuminate\contracts\mail\mailer::class, \illuminate\contracts\mail\mailqueue::class],29     'auth.password'    => [\illuminate\auth\passwords\passwordbrokermanager::class, \illuminate\contracts\auth\passwordbrokerfactory::class],30     'auth.password.broker' => [\illuminate\auth\passwords\passwordbroker::class, \illuminate\contracts\auth\passwordbroker::class],31     'queue'        => [\illuminate\queue\queuemanager::class, \illuminate\contracts\queue\factory::class, \illuminate\cont防汛条例racts\queue\monitor::class],32     'queue.connection'   => [\illuminate\contracts\queue\queue::class],33     'queue.failer'     => [\illuminate\queue\failed\failedjobproviderinterface::class],34     'redirect'       => [\illuminate\routing\redirector::class],35     'redis'        => [\illuminate\redis\redismanager::class, \illuminate\contracts\redis\factory::class],36     'request'       => [\illuminate\http\request::class, \symfony\component\httpfoundation\request::class],37     'router'        => [\illuminate\routing\router::class, \illuminate\contracts\routing\registrar::class, \illuminate\contracts\routing\bindingregistrar::class],38     'ssion'       => [\illuminate\ssion\ssionmanager::class],39     'ssion.store'    => [\illuminate\ssion\store::class, \illuminate\contracts\ssion\ssion::class],40     'url'         => [\illuminate\routing\urlgenerator::class, \illuminate\contracts\routing\urlgenerator::class],41     'validator'      => [\illuminate\validation\factory::class, \illuminate\contracts\validation\factory::class],42     'view'         => [\illuminate\view\factory::class, \illuminate\contracts\view\factory::class],43   ];44   foreach ($alias as $key => $alias) {45     foreach ($alias as $alias) {46       $this->alias($key, $alias);47     }48   }49 }

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

 1 /** 2  * register an existing instance as shared in the container. 3  * 4  * @param string $abstract 5  * @param mixed  $instance 6  * @return void 7  */ 8 public function instance($abstract, $instance) 9 {10   $this->removeabstractalias($abstract);11   unt($this->alias[$abstract]);12   // we'll check to determine if this type has been bound before, and if it has13   // we will fire the rebound callbacks registered with the container and it14   // can be updated with consuming class that have gotten resolved here.15   $this->instances[$abstract] = $instance;16   if ($this->bound($abstract)) {17     $this->rebound($abstract);18   }19 }

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。

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？

 1 <?php 2 namespace app\http; 3 u illuminate\foundation\http\kernel as httpkernel; 4 class kernel extends httpkernel 5 { 6   /** 7    * the application's global http middleware stack. 8    * 9    * the middleware are run during every request to your application.10    *11    *三八妇女节贺卡制作 @var array12    */13   protected $middleware = [14     \illuminate\foundation\http\middleware\checkformaintenancemode::class,15     //\app\http\middleware\mymiddleware::class,16   ];17   /**18    * the application's route middleware groups.19    *20    * @var array21    */22   protected $middlewaregroups = [23     'web' => [24       \app\ht人体最大的器官tp\middleware\encryptcookies::class,25       \illuminate\cookie\middleware\addqueuedcookiestorespon::class,26       \illuminate\ssion\middleware\startssion::class,27       \illuminate\view\middleware\shareerrorsfromssion::class,28       \app\http\middleware\verifycsrftoken::class,29     ],30     'api' => [31       'throttle:60,1',32     ],33   ];34   /**35    * the application's route middleware.36    *37    * the middleware may be assigned to groups or ud individually.38    *39    * @var array40    */41   protected $routemiddleware = [42     'auth' => \app\htt碧潭幽谷p\middleware\authenticate::class,43     'auth.basic' => \illuminate\auth\middleware\authenticatewithbasicauth::class,44     'guest' => \app\http\middleware\redirectifauthenticated::class,45     'throttle' => \illuminate\routing\middleware\throttlerequests::class,46   'mymiddleware'=>\app\http\middleware\mymiddleware::class,47   ];48 }

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

1 $respon = $kernel->handle(2   $request = illuminate\http\request::capture()3 );4 $respon->nd();

最后在中止，释放所有资源。

 1 /** 2 * call the terminate method on any terminable middleware. 3 * 4 * @param \illuminate\http\request $request 5 * @param \illuminate\http\respon $respon 6 * @return void 7 */ 8 public function terminate($request, $respon) 9 {10     $this->terminatemiddleware($request, $respon);11     $this->app->terminate();12 }

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rviceprovider，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