web.php中Auth::routes ();扩展出来的那些路由是从哪里找到的？怎么找到的

在L02web开发进阶的教程中，3.1.用户认证脚手架这一节，web.php有这样一行Auth::routes ()，作用是注册用户认证相关的路由，教程直接把路由贴出来了，但是那些路由具体在哪个文件里面呢。
我用的版本是laravel8,这和旧版本的有一些区别。
首先我用编辑器全局搜索function auth然后一个个找过去，快速确定一个正确答案UiServiceProvider这个文件，然后再顺藤摸瓜慢慢找，步骤如下：
首先找到Auth门面的routes方法，原来是从容器解析了’router’，并且调用了他的auth方法，那么找router是哪个类

  public static function routes(array $options = [])
    {
        if (! static::$app->providerIsLoaded(UiServiceProvider::class)) {
            throw new RuntimeException('In order to use the Auth::routes() method, please install the laravel/ui package.');
        }
        static::$app->make('router')->auth($options);
    }

似乎旧版本app.php的别名配置里面就有个’Route’，会不会和他有关系呢，新版本是这样的

 'aliases' => Facade::defaultAliases()->merge([
        // 'ExampleClass' => App\Example\ExampleClass::class,
    ])->toArray()

找到namespace Illuminate\Support\Facades的defaultAliases方法

    /**
     * Get the application default aliases.
     *
     * @return \Illuminate\Support\Collection
     */
    public static function defaultAliases()
    {
        return collect([
            'App' => App::class,
            'Arr' => Arr::class,
            'Artisan' => Artisan::class,
            'Auth' => Auth::class,
            'Blade' => Blade::class,
            'Broadcast' => Broadcast::class,
            'Bus' => Bus::class,
            'Cache' => Cache::class,
            'Config' => Config::class,
            'Cookie' => Cookie::class,
            'Crypt' => Crypt::class,
            'Date' => Date::class,
            'DB' => DB::class,
            'Eloquent' => Model::class,
            'Event' => Event::class,
            'File' => File::class,
            'Gate' => Gate::class,
            'Hash' => Hash::class,
            'Http' => Http::class,
            'Js' => Js::class,
            'Lang' => Lang::class,
            'Log' => Log::class,
            'Mail' => Mail::class,
            'Notification' => Notification::class,
            'Password' => Password::class,
            'Queue' => Queue::class,
            'RateLimiter' => RateLimiter::class,
            'Redirect' => Redirect::class,
            'Request' => Request::class,
            'Response' => Response::class,
            'Route' => Route::class,
            'Schema' => Schema::class,
            'Session' => Session::class,
            'Storage' => Storage::class,
            'Str' => Str::class,
            'URL' => URL::class,
            'Validator' => Validator::class,
            'View' => View::class,
        ]);
    }

进而找到Route门面的文件

<?php

namespace Illuminate\Support\Facades;

/**
此处省略若干内容
 *
 * @see \Illuminate\Routing\Router
 */
class Route extends Facade
{
    /**
     * Get the registered name of the component.
     *
     * @return string
     */
    protected static function getFacadeAccessor()
    {
        return 'router';
    }
}

注意这一行@see \Illuminate\Routing\Router，这个就是容器里面的Router了(这是后面得到答案后才发现的，原来注释里面有）。
因为注册别名的时候肯定会用到’router’这个词，所以编辑器全局搜索 ，排除掉一些明显不对的，逐个看过去就找到了，一共就那么几个

找到namespace Illuminate\Foundation\Application这个文件中

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

        $this->registerBaseBindings();
        $this->registerBaseServiceProviders();
        $this->registerCoreContainerAliases();
    }
     protected function registerBaseServiceProviders()
    {
        $this->register(new EventServiceProvider($this));
        $this->register(new LogServiceProvider($this));
        $this->register(new RoutingServiceProvider($this));
    }
    public function register($provider, $force = false)
    {
        if (($registered = $this->getProvider($provider)) && ! $force) {
            return $registered;
        }

        // If the given "provider" is a string, we will resolve it, passing in the
        // application instance automatically for the developer. This is simply
        // a more convenient way of specifying your service provider classes.
        if (is_string($provider)) {
            $provider = $this->resolveProvider($provider);
        }

        $provider->register();

        // If there are bindings / singletons set as properties on the provider we
        // will spin through them and register them with the application, which
        // serves as a convenience layer while registering a lot of bindings.
        if (property_exists($provider, 'bindings')) {
            foreach ($provider->bindings as $key => $value) {
                $this->bind($key, $value);
            }
        }

        if (property_exists($provider, 'singletons')) {
            foreach ($provider->singletons as $key => $value) {
                $this->singleton($key, $value);
            }
        }

        $this->markAsRegistered($provider);

        // If the application has already booted, we will call this boot method on
        // the provider class so it has an opportunity to do its boot logic and
        // will be ready for any usage by this developer's application logic.
        if ($this->isBooted()) {
            $this->bootProvider($provider);
        }

        return $provider;
    }
/**
     * Register the core class aliases in the container.
     *
     * @return void
     */
    public function registerCoreContainerAliases()
    {
        foreach ([
            'app' => [self::class, \Illuminate\Contracts\Container\Container::class, \Illuminate\Contracts\Foundation\Application::class, \Psr\Container\ContainerInterface::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, \Psr\SimpleCache\CacheInterface::class],
            'cache.psr6' => [\Symfony\Component\Cache\Adapter\Psr16Adapter::class, \Symfony\Component\Cache\Adapter\AdapterInterface::class, \Psr\Cache\CacheItemPoolInterface::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],
            'db' => [\Illuminate\Database\DatabaseManager::class, \Illuminate\Database\ConnectionResolverInterface::class],
            'db.connection' => [\Illuminate\Database\Connection::class, \Illuminate\Database\ConnectionInterface::class],
            'db.schema' => [\Illuminate\Database\Schema\Builder::class],
            'encrypter' => [\Illuminate\Encryption\Encrypter::class, \Illuminate\Contracts\Encryption\Encrypter::class, \Illuminate\Contracts\Encryption\StringEncrypter::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\Hashing\HashManager::class],
            'hash.driver' => [\Illuminate\Contracts\Hashing\Hasher::class],
            'translator' => [\Illuminate\Translation\Translator::class, \Illuminate\Contracts\Translation\Translator::class],
            'log' => [\Illuminate\Log\LogManager::class, \Psr\Log\LoggerInterface::class],
            'mail.manager' => [\Illuminate\Mail\MailManager::class, \Illuminate\Contracts\Mail\Factory::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],
            'redis.connection' => [\Illuminate\Redis\Connections\Connection::class, \Illuminate\Contracts\Redis\Connection::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],
        ] as $key => $aliases) {
            foreach ($aliases as $alias) {
                $this->alias($key, $alias);
            }
        }
    }

首先构造函数中调用了registerBaseServiceProviders方法，里面再调用register方法注册了RoutingServiceProvider，注册时会调用RoutingServiceProvider的register方法,里面又调用registerRouter方法，往容器注入了一个Router单例

    public function register()
    {
        $this->registerRouter();
        $this->registerUrlGenerator();
        $this->registerRedirector();
        $this->registerPsrRequest();
        $this->registerPsrResponse();
        $this->registerResponseFactory();
        $this->registerControllerDispatcher();
    }
        protected function registerRouter()
    {
        $this->app->singleton('router', function ($app) {
            return new Router($app['events'], $app);
        });
    }

看注释可以知道registerCoreContainerAliases这个方法在容器里注册了一些核心类的别名，解析router别名的时候，相当于解析\Illuminate\Routing\Router的实例，由于已经注入了一个单例，就会直接返回那个单例。
现在回到Auth门面的routes方法。
当Route门面静态调用auth的时候，由于没有这个方法，会走魔术方法调用getFacadeRoot，再调用Route门面的getFacadeAccessor方法，返回’router’，然后传给resolveFacadeInstance方法，如果已经解析过门面，就直接返回，没有解析过的，就去容器找’router’，得到Router单例。

 /**
     * Handle dynamic, static calls to the object.
     *
     * @param  string  $method
     * @param  array  $args
     * @return mixed
     *
     * @throws \RuntimeException
     */
    public static function __callStatic($method, $args)
    {
        $instance = static::getFacadeRoot();

        if (! $instance) {
            throw new RuntimeException('A facade root has not been set.');
        }

        return $instance->$method(...$args);
    }
  public static function getFacadeRoot()
    {
        return static::resolveFacadeInstance(static::getFacadeAccessor());
    }
   protected static function resolveFacadeInstance($name)
    {
        if (isset(static::$resolvedInstance[$name])) {
            return static::$resolvedInstance[$name];
        }

        if (static::$app) {
            if (static::$cached) {
                return static::$resolvedInstance[$name] = static::$app[$name];
            }

            return static::$app[$name];
        }
    }

拿到Router之后，新版本的路由并不在Router里面，而是在 Laravel\Ui\UiServiceProvider里面，由于自动加载机制（这个没深究），加载时自动调用boot方法，里面再调mixin方法，但是Router里面并没有mixin方法，他是怎么来的？

 public function boot()
    {
        Route::mixin(new AuthRouteMethods);
    }

全局搜索function mixin，结果找到了Macroable这个文件，原来是Router上面use了Macroable

    use Macroable {
        __call as macroCall;
    }

macroCall中就有mixin方法

    public static function mixin($mixin, $replace = true)
    {
        $methods = (new ReflectionClass($mixin))->getMethods(
            ReflectionMethod::IS_PUBLIC | ReflectionMethod::IS_PROTECTED
        );

        foreach ($methods as $method) {
            if ($replace || ! static::hasMacro($method->name)) {
                $method->setAccessible(true);
                static::macro($method->name, $method->invoke($mixin));
            }
        }
    }

mixin方法通过反射，将AuthRouteMethods的public和protected方法扩展到了Router上，而AuthRouteMethods中就有auth方法

public function auth()
    {
        return function ($options = []) {
            $namespace = class_exists($this->prependGroupNamespace('Auth\LoginController')) ? null : 'App\Http\Controllers';

            $this->group(['namespace' => $namespace], function() use($options) {
                // Login Routes...
                if ($options['login'] ?? true) {
                    $this->get('login', 'Auth\LoginController@showLoginForm')->name('login');
                    $this->post('login', 'Auth\LoginController@login');
                }

                // Logout Routes...
                if ($options['logout'] ?? true) {
                    $this->post('logout', 'Auth\LoginController@logout')->name('logout');
                }

                // Registration Routes...
                if ($options['register'] ?? true) {
                    $this->get('register', 'Auth\RegisterController@showRegistrationForm')->name('register');
                    $this->post('register', 'Auth\RegisterController@register');
                }

                // Password Reset Routes...
                if ($options['reset'] ?? true) {
                    $this->resetPassword();
                }

                // Password Confirmation Routes...
                if ($options['confirm'] ??
                    class_exists($this->prependGroupNamespace('Auth\ConfirmPasswordController'))) {
                    $this->confirmPassword();
                }

                // Email Verification Routes...
                if ($options['verify'] ?? false) {
                    $this->emailVerification();
                }
            });
        };
    }

总结：当在web.php中调用Route:auth()的时候，门面解析到Router实例，然后通过反射调用了扩展到Router的AuthRouteMethods的auth方法。

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