Laravel之Contracts和Facades详解

约定不等于承诺〃 2023-07-26 05:26 19阅读 0赞

**Contracts**

Contracts其实就是倡导面向接口编程，来达到解耦的目的。而这些通用的接口已经由Laravel为你设计好了。就是这些Contracts.

那么Laravel如何知道我们需要使用哪个实现呢？

在Laravel默认的Contracts绑定中，在'Illuminate/Foundation/Application.php'有这样的定义:这就是绑定了默认的接口实现.

/**
    
         * Register the core class aliases in the container.
    
         *
    
         * @return void
    
         */
    
        public function registerCoreContainerAliases()
    
        {
    
            $aliases = [
    
                'app'                  => ['Illuminate\Foundation\Application', 'Illuminate\Contracts\Container\Container', 'Illuminate\Contracts\Foundation\Application'],
    
                'auth'                 => 'Illuminate\Auth\AuthManager',
    
                'auth.driver'          => ['Illuminate\Auth\Guard', 'Illuminate\Contracts\Auth\Guard'],
    
                'auth.password.tokens' => 'Illuminate\Auth\Passwords\TokenRepositoryInterface',
    
                'blade.compiler'       => 'Illuminate\View\Compilers\BladeCompiler',
    
                'cache'                => ['Illuminate\Cache\CacheManager', 'Illuminate\Contracts\Cache\Factory'],
    
                'cache.store'          => ['Illuminate\Cache\Repository', 'Illuminate\Contracts\Cache\Repository'],
    
                'config'               => ['Illuminate\Config\Repository', 'Illuminate\Contracts\Config\Repository'],
    
                'cookie'               => ['Illuminate\Cookie\CookieJar', 'Illuminate\Contracts\Cookie\Factory', 'Illuminate\Contracts\Cookie\QueueingFactory'],
    
                'encrypter'            => ['Illuminate\Encryption\Encrypter', 'Illuminate\Contracts\Encryption\Encrypter'],
    
                'db'                   => 'Illuminate\Database\DatabaseManager',
    
                'db.connection'        => ['Illuminate\Database\Connection', 'Illuminate\Database\ConnectionInterface'],
    
                'events'               => ['Illuminate\Events\Dispatcher', 'Illuminate\Contracts\Events\Dispatcher'],
    
                'files'                => 'Illuminate\Filesystem\Filesystem',
    
                'filesystem'           => ['Illuminate\Filesystem\FilesystemManager', 'Illuminate\Contracts\Filesystem\Factory'],
    
                'filesystem.disk'      => 'Illuminate\Contracts\Filesystem\Filesystem',
    
                'filesystem.cloud'     => 'Illuminate\Contracts\Filesystem\Cloud',
    
                'hash'                 => 'Illuminate\Contracts\Hashing\Hasher',
    
                'translator'           => ['Illuminate\Translation\Translator', 'Symfony\Component\Translation\TranslatorInterface'],
    
                'log'                  => ['Illuminate\Log\Writer', 'Illuminate\Contracts\Logging\Log', 'Psr\Log\LoggerInterface'],
    
                'mailer'               => ['Illuminate\Mail\Mailer', 'Illuminate\Contracts\Mail\Mailer', 'Illuminate\Contracts\Mail\MailQueue'],
    
                'auth.password'        => ['Illuminate\Auth\Passwords\PasswordBroker', 'Illuminate\Contracts\Auth\PasswordBroker'],
    
                'queue'                => ['Illuminate\Queue\QueueManager', 'Illuminate\Contracts\Queue\Factory', 'Illuminate\Contracts\Queue\Monitor'],
    
                'queue.connection'     => 'Illuminate\Contracts\Queue\Queue',
    
                'redirect'             => 'Illuminate\Routing\Redirector',
    
                'redis'                => ['Illuminate\Redis\Database', 'Illuminate\Contracts\Redis\Database'],
    
                'request'              => 'Illuminate\Http\Request',
    
                'router'               => ['Illuminate\Routing\Router', 'Illuminate\Contracts\Routing\Registrar'],
    
                'session'              => 'Illuminate\Session\SessionManager',
    
                'session.store'        => ['Illuminate\Session\Store', 'Symfony\Component\HttpFoundation\Session\SessionInterface'],
    
                'url'                  => ['Illuminate\Routing\UrlGenerator', 'Illuminate\Contracts\Routing\UrlGenerator'],
    
                'validator'            => ['Illuminate\Validation\Factory', 'Illuminate\Contracts\Validation\Factory'],
    
                'view'                 => ['Illuminate\View\Factory', 'Illuminate\Contracts\View\Factory'],
    
            ];

在我们自定义的接口实现时，我们可以在ServiceProvider中使用进行绑定:

$this->app->bind('App\Contracts\EventPusher', 'App\Services\PusherEventPusher');

**Facades**

Facades 为应用程序的服务容器中可用的类提供了一个「静态」接口。Laravel 「facades」作为在服务容器内基类的「静态代理」。很难懂？

我们打开项目目录下的config/app.php，然后找到

/*
    
        |--------------------------------------------------------------------------
    
        | Class Aliases
    
        |--------------------------------------------------------------------------
    
        |
    
        | This array of class aliases will be registered when this application
    
        | is started. However, feel free to register as many as you wish as
    
        | the aliases are "lazy" loaded so they don't hinder performance.
    
        |
    
        */
    
        'aliases' => [
    
            'App'       => Illuminate\Support\Facades\App::class,
    
            'Artisan'   => Illuminate\Support\Facades\Artisan::class,
    
            'Auth'      => Illuminate\Support\Facades\Auth::class,
    
            'Blade'     => Illuminate\Support\Facades\Blade::class,
    
            'Bus'       => Illuminate\Support\Facades\Bus::class,
    
            'Cache'     => Illuminate\Support\Facades\Cache::class,
    
            'Config'    => Illuminate\Support\Facades\Config::class,
    
            'Cookie'    => Illuminate\Support\Facades\Cookie::class,
    
            'Crypt'     => Illuminate\Support\Facades\Crypt::class,
    
            'DB'        => Illuminate\Support\Facades\DB::class,
    
            'Eloquent'  => Illuminate\Database\Eloquent\Model::class,
    
            'Event'     => Illuminate\Support\Facades\Event::class,
    
            'File'      => Illuminate\Support\Facades\File::class,
    
            'Gate'      => Illuminate\Support\Facades\Gate::class,
    
            'Hash'      => Illuminate\Support\Facades\Hash::class,
    
            'Input'     => Illuminate\Support\Facades\Input::class,
    
            'Lang'      => Illuminate\Support\Facades\Lang::class,
    
            'Log'       => Illuminate\Support\Facades\Log::class,
    
            'Mail'      => Illuminate\Support\Facades\Mail::class,
    
            'Password'  => Illuminate\Support\Facades\Password::class,
    
            'Queue'     => Illuminate\Support\Facades\Queue::class,
    
            'Redirect'  => Illuminate\Support\Facades\Redirect::class,
    
            'Redis'     => Illuminate\Support\Facades\Redis::class,
    
            'Request'   => Illuminate\Support\Facades\Request::class,
    
            'Response'  => Illuminate\Support\Facades\Response::class,
    
            'Route'     => Illuminate\Support\Facades\Route::class,
    
            'Schema'    => Illuminate\Support\Facades\Schema::class,
    
            'Session'   => Illuminate\Support\Facades\Session::class,
    
            'Storage'   => Illuminate\Support\Facades\Storage::class,
    
            'URL'       => Illuminate\Support\Facades\URL::class,
    
            'Validator' => Illuminate\Support\Facades\Validator::class,
    
            'View'      => Illuminate\Support\Facades\View::class,
    
        ],

你是不是发现了什么？对，Facades其实就是在config/app.php中定义的一系列类的别名。只不过这些类都具有一个共同的特点，那就是继承基底 Illuminate\\Support\\Facades\\Facade 类并实现一个方法：getFacadeAccessor返回名称。

**自定义Facade**

参考[http://www.tutorialspoint.com/laravel/laravel\_facades.htm][http_www.tutorialspoint.com_laravel_laravel_facades.htm]

**Step 1** −创建一个名为 TestFacadesServiceProvider的ServiceProvider ,使用如下命令即可:

php artisan make:provider TestFacadesServiceProvider

**Step 2 **− 创建一个底层代理类，命名为“TestFacades.php” at “App/Test”.

App/Test/TestFacades.php

<?php
    
    namespace App\Test;
    
    class TestFacades{
    
       public function testingFacades(){
    
          echo "Testing the Facades in Laravel.";
    
       }
    
    }
    
    ?>

**Step 3 **− 创建一个 Facade 类 called “TestFacades.php” at “App/Test/Facades”.

App/Test/Facades/TestFacades.php

<?php
    
    namespace app\Test\Facades;
    
    use Illuminate\Support\Facades\Facade;
    
    class TestFacades extends Facade{
    
       protected static function getFacadeAccessor() { return 'test'; }
    
    }

**Step 4** −创建一个ServiceProviders类，名为“TestFacadesServiceProviders.php” at “App/Test/Facades”.

App/Providers/TestFacadesServiceProviders.php

<?php
    namespace App\Providers;
    use App;
    use Illuminate\Support\ServiceProvider;
    class TestFacadesServiceProvider extends ServiceProvider {
     public function boot() {
     //
     }
     public function register() {
     //可以这么绑定,这需要use App;
     //  App::bind('test',function() {
     //     return new \App\Test\TestFacades;
     //  });
      
     //也可以这么绑定，推荐。这个test对应于Facade的getFacadeAccessor返回值
     $this->app->bind("test", function(){
     return new MyFoo(); //给这个Facade返回一个代理实例。所有对Facade的调用都会被转发到该类对象下。
     });
     }
    }

**Step 5 **− 在config/app.php注册ServiceProvider类

**Step 6** − 在config/app.php注册自定义Facade的别名

使用测试：

Add the following lines in app/Http/routes.php.

Route::get('/facadeex', function(){
     return TestFacades::testingFacades();
    });

**Step 9** − Visit the following URL to test the Facade.

http://localhost:8000/facadeex去查看输出

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