# 架構 —— 門面（Facades） ## 1、簡介 門面為應用的服務容器中的有效類提供了一個“靜態”接口。Laravel附帶了很多門面，你可能在不知道的情況下正在使用它們。Laravel的門面作為服務容器中的底層類的“靜態代理”，相比于傳統靜態方法，在維護時能夠提供更加易于測試、更加靈活的、簡明且富有表現力的語法。 ## 2、使用門面 在Laravel應用的上下文中，門面就是一個提供訪問容器中對象的類。該機制原理由`Facade`類實現，Laravel自帶的門面，以及創建的自定義門面，都會繼承自`Illuminate\Support\Facades\Facade`基類。 門面類只需要實現一個方法：`getFacadeAccessor`。正是`getFacadeAccessor`方法定義了從容器中解析什么，然后`Facade`基類使用魔術方法從你的門面中調用解析對象。 下面的例子中，我們將會調用Laravel的緩存系統，瀏覽代碼后，也許你會覺得我們調用了`Cache`的靜態方法`get`： ~~~ <?php namespace App\Http\Controllers; use Cache; use App\Http\Controllers\Controller; class UserController extends Controller{ /** * 為指定用戶顯示屬性 * * @param int $id * @return Response */ public function showProfile($id) { $user = Cache::get('user:'.$id); return view('profile', ['user' => $user]); } } ~~~ 注意我們在頂部位置引入了Cache門面。該門面作為代理訪問底層`Illuminate\Contracts\Cache\Factory`接口的實現。我們對門面的所有調用都會被傳遞給Laravel緩存服務的底層實例。 如果我們查看`Illuminate\Support\Facades\Cache`類的源碼，將會發現其中并沒有靜態方法`get`： ~~~ class Cache extends Facade{ /** * 獲取組件注冊名稱 * * @return string */ protected static function getFacadeAccessor() { return 'cache'; } } ~~~ `Cache`門面繼承`Facade`基類并定義了`getFacadeAccessor`方法，該方法的工作就是返回服務容器綁定類的別名，當用戶引用`Cache`類的任何靜態方法時，Laravel從服務容器中解析cache綁定，然后在解析出的對象上調用所有請求方法（本例中是get）。 > 擴展閱讀：[實例教程 —— 創建自定義Facades類](http://laravelacademy.org/post/817.html) ## 3、門面類列表 下面列出了每個門面及其對應的底層類，這對深入給定根門面的API[文檔](http://laravelacademy.org/tags/%e6%96%87%e6%a1%a3 "View all posts in 文檔")而言是個很有用的工具。服務容器綁定鍵也被包含進來： | 門面 | 類 | 服務容器綁定別名 | | --- | --- | --- | | App | [Illuminate\Foundation\Application](http://laravel.com/api/5.1/Illuminate/Foundation/Application.html) | `app` | | Artisan | [Illuminate\Console\Application](http://laravel.com/api/5.1/Illuminate/Console/Application.html) | `artisan` | | Auth | [Illuminate\Auth\AuthManager](http://laravel.com/api/5.1/Illuminate/Auth/AuthManager.html) | `auth` | | Auth (Instance) | [Illuminate\Auth\Guard](http://laravel.com/api/5.1/Illuminate/Auth/Guard.html) | | | Blade | [Illuminate\View\Compilers\BladeCompiler](http://laravel.com/api/5.1/Illuminate/View/Compilers/BladeCompiler.html) | `blade.compiler` | | Bus | [Illuminate\Contracts\Bus\Dispatcher](http://laravel.com/api/5.1/Illuminate/Contracts/Bus/Dispatcher.html) | | | Cache | [Illuminate\Cache\Repository](http://laravel.com/api/5.1/Illuminate/Cache/Repository.html) | `cache` | | Config | [Illuminate\Config\Repository](http://laravel.com/api/5.1/Illuminate/Config/Repository.html) | `config` | | Cookie | [Illuminate\Cookie\CookieJar](http://laravel.com/api/5.1/Illuminate/Cookie/CookieJar.html) | `cookie` | | Crypt | [Illuminate\Encryption\Encrypter](http://laravel.com/api/5.1/Illuminate/Encryption/Encrypter.html) | `encrypter` | | DB | [Illuminate\Database\DatabaseManager](http://laravel.com/api/5.1/Illuminate/Database/DatabaseManager.html) | `db` | | DB (Instance) | [Illuminate\Database\Connection](http://laravel.com/api/5.1/Illuminate/Database/Connection.html) | | | Event | [Illuminate\Events\Dispatcher](http://laravel.com/api/5.1/Illuminate/Events/Dispatcher.html) | `events` | | File | [Illuminate\Filesystem\Filesystem](http://laravel.com/api/5.1/Illuminate/Filesystem/Filesystem.html) | `files` | | Hash | [Illuminate\Contracts\Hashing\Hasher](http://laravel.com/api/5.1/Illuminate/Contracts/Hashing/Hasher.html) | `hash` | | Input | [Illuminate\Http\Request](http://laravel.com/api/5.1/Illuminate/Http/Request.html) | `request` | | Lang | [Illuminate\Translation\Translator](http://laravel.com/api/5.1/Illuminate/Translation/Translator.html) | `translator` | | Log | [Illuminate\Log\Writer](http://laravel.com/api/5.1/Illuminate/Log/Writer.html) | `log` | | Mail | [Illuminate\Mail\Mailer](http://laravel.com/api/5.1/Illuminate/Mail/Mailer.html) | `mailer` | | Password | [Illuminate\Auth\Passwords\PasswordBroker](http://laravel.com/api/5.1/Illuminate/Auth/Passwords/PasswordBroker.html) | `auth.password` | | Queue | [Illuminate\Queue\QueueManager](http://laravel.com/api/5.1/Illuminate/Queue/QueueManager.html) | `queue` | | Queue (Instance) | [Illuminate\Queue\QueueInterface](http://laravel.com/api/5.1/Illuminate/Queue/QueueInterface.html) | | | Queue (Base Class) | [Illuminate\Queue\Queue](http://laravel.com/api/5.1/Illuminate/Queue/Queue.html) | | | Redirect | [Illuminate\Routing\Redirector](http://laravel.com/api/5.1/Illuminate/Routing/Redirector.html) | `redirect` | | Redis | [Illuminate\Redis\Database](http://laravel.com/api/5.1/Illuminate/Redis/Database.html) | `redis` | | Request | [Illuminate\Http\Request](http://laravel.com/api/5.1/Illuminate/Http/Request.html) | `request` | | Response | [Illuminate\Contracts\Routing\ResponseFactory](http://laravel.com/api/5.1/Illuminate/Contracts/Routing/ResponseFactory.html) | | | Route | [Illuminate\Routing\Router](http://laravel.com/api/5.1/Illuminate/Routing/Router.html) | `router` | | Schema | [Illuminate\Database\Schema\Blueprint](http://laravel.com/api/5.1/Illuminate/Database/Schema/Blueprint.html) | | | Session | [Illuminate\Session\SessionManager](http://laravel.com/api/5.1/Illuminate/Session/SessionManager.html) | `session` | | Session (Instance) | [Illuminate\Session\Store](http://laravel.com/api/5.1/Illuminate/Session/Store.html) | | | Storage | [Illuminate\Contracts\Filesystem\Factory](http://laravel.com/api/5.1/Illuminate/Contracts/Filesystem/Factory.html) | `filesystem` | | URL | [Illuminate\Routing\UrlGenerator](http://laravel.com/api/5.1/Illuminate/Routing/UrlGenerator.html) | `url` | | Validator | [Illuminate\Validation\Factory](http://laravel.com/api/5.1/Illuminate/Validation/Factory.html) | `validator` | | Validator (Instance) | [Illuminate\Validation\Validator](http://laravel.com/api/5.1/Illuminate/Validation/Validator.html) | | | View | [Illuminate\View\Factory](http://laravel.com/api/5.1/Illuminate/View/Factory.html) | `view` | | View (Instance) | [Illuminate\View\View](http://laravel.com/api/5.1/Illuminate/View/View.html) |