Laravel之Contracts和Facades详解

概述Laravel之Contracts和Facades详解 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.

推荐：《laravel教程》

/**     * 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\@R_806_4403@Factory'],            '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

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

<?PHPnamespace 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

<?PHPnamespace 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

<?PHPnamespace 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 总结

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