Laravel之Contracts和Facades详解

发布时间：2020-12-14 19:33:17 所属栏目：大数据来源：网络整理

导读：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

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'                  => ['IlluminateFoundationApplication','IlluminateContractsContainerContainer','IlluminateContractsFoundationApplication'],'auth'                 => 'IlluminateAuthAuthManager','auth.driver'          => ['IlluminateAuthGuard','IlluminateContractsAuthGuard'],'auth.password.tokens' => 'IlluminateAuthPasswordsTokenRepositoryInterface','blade.compiler'       => 'IlluminateViewCompilersBladeCompiler','cache'                => ['IlluminateCacheCacheManager','IlluminateContractsCacheFactory'],'cache.store'          => ['IlluminateCacheRepository','IlluminateContractsCacheRepository'],'config'               => ['IlluminateConfigRepository','IlluminateContractsConfigRepository'],'cookie'               => ['IlluminateCookieCookieJar','IlluminateContractsCookieFactory','IlluminateContractsCookieQueueingFactory'],'encrypter'            => ['IlluminateEncryptionEncrypter','IlluminateContractsEncryptionEncrypter'],'db'                   => 'IlluminateDatabaseDatabaseManager','db.connection'        => ['IlluminateDatabaseConnection','IlluminateDatabaseConnectionInterface'],'events'               => ['IlluminateEventsDispatcher','IlluminateContractsEventsDispatcher'],'files'                => 'IlluminateFilesystemFilesystem','filesystem'           => ['IlluminateFilesystemFilesystemManager','IlluminateContractsFilesystemFactory'],'filesystem.disk'      => 'IlluminateContractsFilesystemFilesystem','filesystem.cloud'     => 'IlluminateContractsFilesystemCloud','hash'                 => 'IlluminateContractsHashingHasher','translator'           => ['IlluminateTranslationTranslator','SymfonyComponentTranslationTranslatorInterface'],'log'                  => ['IlluminateLogWriter','IlluminateContractsLoggingLog','PsrLogLoggerInterface'],'mailer'               => ['IlluminateMailMailer','IlluminateContractsMailMailer','IlluminateContractsMailMailQueue'],'auth.password'        => ['IlluminateAuthPasswordsPasswordBroker','IlluminateContractsAuthPasswordBroker'],'queue'                => ['IlluminateQueueQueueManager','IlluminateContractsQueueFactory','IlluminateContractsQueueMonitor'],'queue.connection'     => 'IlluminateContractsQueueQueue','redirect'             => 'IlluminateRoutingRedirector','redis'                => ['IlluminateRedisDatabase','IlluminateContractsRedisDatabase'],'request'              => 'IlluminateHttpRequest','router'               => ['IlluminateRoutingRouter','IlluminateContractsRoutingRegistrar'],'session'              => 'IlluminateSessionSessionManager','session.store'        => ['IlluminateSessionStore','SymfonyComponentHttpFoundationSessionSessionInterface'],'url'                  => ['IlluminateRoutingUrlGenerator','IlluminateContractsRoutingUrlGenerator'],'validator'            => ['IlluminateValidationFactory','IlluminateContractsValidationFactory'],'view'                 => ['IlluminateViewFactory','IlluminateContractsViewFactory'],];

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('AppContractsEventPusher','AppServicesPusherEventPusher');

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'       => IlluminateSupportFacadesApp::class,'Artisan'   => IlluminateSupportFacadesArtisan::class,'Auth'      => IlluminateSupportFacadesAuth::class,'Blade'     => IlluminateSupportFacadesBlade::class,'Bus'       => IlluminateSupportFacadesBus::class,'Cache'     => IlluminateSupportFacadesCache::class,'Config'    => IlluminateSupportFacadesConfig::class,'Cookie'    => IlluminateSupportFacadesCookie::class,'Crypt'     => IlluminateSupportFacadesCrypt::class,'DB'        => IlluminateSupportFacadesDB::class,'Eloquent'  => IlluminateDatabaseEloquentModel::class,'Event'     => IlluminateSupportFacadesEvent::class,'File'      => IlluminateSupportFacadesFile::class,'Gate'      => IlluminateSupportFacadesGate::class,'Hash'      => IlluminateSupportFacadesHash::class,'Input'     => IlluminateSupportFacadesInput::class,'Lang'      => IlluminateSupportFacadesLang::class,'Log'       => IlluminateSupportFacadesLog::class,'Mail'      => IlluminateSupportFacadesMail::class,'Password'  => IlluminateSupportFacadesPassword::class,'Queue'     => IlluminateSupportFacadesQueue::class,'Redirect'  => IlluminateSupportFacadesRedirect::class,'Redis'     => IlluminateSupportFacadesRedis::class,'Request'   => IlluminateSupportFacadesRequest::class,'Response'  => IlluminateSupportFacadesResponse::class,'Route'     => IlluminateSupportFacadesRoute::class,'Schema'    => IlluminateSupportFacadesSchema::class,'Session'   => IlluminateSupportFacadesSession::class,'Storage'   => IlluminateSupportFacadesStorage::class,'URL'       => IlluminateSupportFacadesURL::class,'Validator' => IlluminateSupportFacadesValidator::class,'View'      => IlluminateSupportFacadesView::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 IlluminateSupportFacadesFacade 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 AppTest;

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 appTestFacades;

use IlluminateSupportFacadesFacade;

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 AppProviders;
use App;
use IlluminateSupportServiceProvider;
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 AppTestTestFacades;
 //  });
  
 //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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