Laravel生命周期与原理
程序员文章站
2022-05-10 09:33:45
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。
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);
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 serves 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 interfaces 18 |-------------------------------------------------------------------------- 19 | 20 | next, we need to bind some important interfaces into the container so 21 | we will be able to resolve them when needed. the kernels serve the 22 | 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::class 28 ); 29 $app->singleton( 30 illuminate\contracts\console\kernel::class, 31 app\console\kernel::class 32 ); 33 $app->singleton( 34 illuminate\contracts\debug\exceptionhandler::class, 35 app\exceptions\handler::class 36 ); 37 /* 38 |-------------------------------------------------------------------------- 39 | return the application 40 |-------------------------------------------------------------------------- 41 | 42 | this script returns the application instance. the instance is given to 43 | the calling script so we can separate the building of the instances 44 | from the actual running of the application and sending responses. 45 | 46 */ 47 return $app;
请看app变量是illuminate\foundation\application类的对象，所以调用了这个类的构造函数，具体做了什么事，我们看源码。
1 public function __construct($basepath = null)
2 {
3 if ($basepath) {
4 $this->setbasepath($basepath);
5 }
6 $this->registerbasebindings();
7 $this->registerbaseserviceproviders();
8 $this->registercorecontaineraliases();
9 }
构造器做了3件事，前两件事很好理解，创建container，注册了serviceprovider，看代码
1 /**
2 * register the basic bindings into the container.
3 *
4 * @return void
5 */
6 protected function registerbasebindings()
7 {
8 static::setinstance($this);
9 $this->instance('app', $this);
10 $this->instance(container::class, $this);
11 }
12 /**
13 * register all of the base service providers.
14 *
15 * @return void
16 */
17 protected function registerbaseserviceproviders()
18 {
19 $this->register(new eventserviceprovider($this));
20 $this->register(new logserviceprovider($this));
21 $this->register(new routingserviceprovider($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 aliases in the container.
3 *
4 * @return void
5 */
6 public function registercorecontaineraliases()
7 {
8 $aliases = [
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\database\databasemanager::class],
19 'db.connection' => [\illuminate\database\connection::class, \illuminate\database\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\contracts\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 'session' => [\illuminate\session\sessionmanager::class],
39 'session.store' => [\illuminate\session\store::class, \illuminate\contracts\session\session::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 ($aliases as $key => $aliases) {
45 foreach ($aliases 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 unset($this->aliases[$abstract]);
12 // we'll check to determine if this type has been bound before, and if it has
13 // we will fire the rebound callbacks registered with the container and it
14 // can be updated with consuming classes 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 use illuminate\foundation\http\kernel as httpkernel;
4 class kernel extends httpkernel
5 {
6 /**
7 * the application's global http middleware stack.
8 *
9 * these middleware are run during every request to your application.
10 *
11 * @var array
12 */
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 array
21 */
22 protected $middlewaregroups = [
23 'web' => [
24 \app\http\middleware\encryptcookies::class,
25 \illuminate\cookie\middleware\addqueuedcookiestoresponse::class,
26 \illuminate\session\middleware\startsession::class,
27 \illuminate\view\middleware\shareerrorsfromsession::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 * these middleware may be assigned to groups or used individually.
38 *
39 * @var array
40 */
41 protected $routemiddleware = [
42 'auth' => \app\http\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 $response = $kernel->handle( 2 $request = illuminate\http\request::capture() 3 ); 4 $response->send();
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\response $response
6 * @return void
7 */
8 public function terminate($request, $response)
9 {
10 $this->terminatemiddleware($request, $response);
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