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.

/**

     * 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

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

Laravel之Contracts和Facades详解

相关推荐