laravel中检测用户是否登录，有以下的代码：
if ( !Auth::guest() ) { return Redirect::to('/dashboard'); }
那Auth::guest是如何调用的呢？
laravel用了Facade模式，相关门面类在laravel/framework/src/Illuminate/Support/Facades文件夹定义的，看下Auth类的定义：
class Auth extends Facade { /** * Get the registered name of the component. * * @return string */ protected static function getFacadeAccessor() { return 'auth'; } }
laravel框架中，Facade模式使用反射，相关方法其实调用app['auth']中的方法，app['auth']是什么时候创建的呢，
AuthServiceProvider::register方法会注册：
$this->app->bindShared('auth', function($app) { // Once the authentication service has actually been requested by the developer // we will set a variable in the application indicating such. This helps us // know that we need to set any queued cookies in the after event later. $app['auth.loaded'] = true; return new AuthManager($app); });
那为什么最终会调到哪里呢，看下堆栈：
Illuminate\Support\Facades\Auth::guest() Illuminate\Support\Facades\Facade::__callStatic Illuminate\Auth\AuthManager->guest() Illuminate\Support\Manager->__call public function __call($method, $parameters) { return call_user_func_array(array($this->driver(), $method), $parameters); }
看下driver的代码：
public function driver($driver = null) { $driver = $driver ?: $this->getDefaultDriver(); // If the given driver has not been created before, we will create the instances // here and cache it so we can return it next time very quickly. If there is // already a driver created by this name, we'll just return that instance. if ( ! isset($this->drivers[$driver])) { $this->drivers[$driver] = $this->createDriver($driver); } return $this->drivers[$driver]; }
没有会调用getDefaultDrive方法
/** * Get the default authentication driver name. * * @return string */ public function getDefaultDriver() { return $this->app['config']['auth.driver']; }
最终调用的是配置文件中配置的driver，如果配的是
'driver' => 'eloquent'
则调用的是
public function createEloquentDriver() { $provider = $this->createEloquentProvider(); return new Guard($provider, $this->app['session.store']); }
所以Auth::guest最终调用的是Guard::guest方法
这里的逻辑先从session中取用户信息，奇怪的是session里只保存的是用户ID，然后拿这个ID来从数据库中取用户信息
public function user() { if ($this->loggedOut) return; // If we have already retrieved the user for the current request we can just // return it back immediately. We do not want to pull the user data every // request into the method because that would tremendously slow an app. if ( ! is_null($this->user)) { return $this->user; } $id = $this->session->get($this->getName()); // First we will try to load the user using the identifier in the session if // one exists. Otherwise we will check for a "remember me" cookie in this // request, and if one exists, attempt to retrieve the user using that. $user = null; if ( ! is_null($id)) { //provider为EloquentUserProvider $user = $this->provider->retrieveByID($id); } // If the user is null, but we decrypt a "recaller" cookie we can attempt to // pull the user data on that cookie which serves as a remember cookie on // the application. Once we have a user we can return it to the caller. $recaller = $this->getRecaller(); if (is_null($user) && ! is_null($recaller)) { $user = $this->getUserByRecaller($recaller); } return $this->user = $user; }
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