设计模式对每个开发人员都非常重要。 它能解决项目中的常见问题。

Facade 模式定义

Facade 可帮助您隐藏类的任何复杂实现，以获取类的实例。

维基百科

Facade 是充当前端接口的对象，可掩盖更复杂的基础或结构代码。

问题

假设我们有一个CMS，每发布一个新帖子，我们都希望发布一条推文。

首先，我们使用 dg/twitter-php 库发送推文。在 README 文件中，以下代码将发布一条推文。

use DG\Twitter\Twitter;

$twitter = new Twitter($consumerKey, $consumerSecret, $accessToken, $accessTokenSecret);

$twitter->send('I am fine today.');

注意，每次需要获取 Twitter 实例时，都需要传递一些加密数据。但我们不希望每次发送推文时都要传递这些数据。

此外，我们不需要工厂(工厂模式)，因为我们只想发送推文，如果在这里使用工厂的话，会让事情变得更复杂。

因此 Facade 模式可以通过创建 Facade 类来帮助我们隐藏创建实例的复杂性

class TwitterFacade 
{
  public static function get()
  {
    return new Twitter($consumerKey, $consumerSecret, $accessToken, $accessTokenSecret);
  }
}

在 Laravel 把加密数据放入 config / services.php中。

'twitter' => [
    'api_key' => env('TWITTER_API_KEY'),
    'api_secret' => env('TWITTER_API_SECRET'),
    'api_token' => env('TWITTER_Access_TOKEN'),
    'api_token_secret' => env('TWITTER_Access_TOKEN_SECRET'),
],

更新 Facade 类以使用如下配置：

class TwitterFacade 
{
  public static function get()
  {
      $config = config('services.twitter');
      return new Twitter($config['api_key'], $config['api_secret'], $config['api_token'], $config['api_token_secret']);
  }
}

现在，每当我们要发送推文时，我们只需写一行

TwitterFacade::get()->send('Test tweet from a facade class');

在 Laravel 中使用 Facade

Laravel 支持 Facade 模式及其一部分核心系统。 如果你打开 config/app.php 并滚动到 aliases ，你会看到一堆 Facades

'aliases' => [

    'App' => Illuminate\Support\Facades\App::class,
    'Arr' => Illuminate\Support\Arr::class,
    'Artisan' => Illuminate\Support\Facades\Artisan::class,
    'Auth' => Illuminate\Support\Facades\Auth::class,
    'Blade' => Illuminate\Support\Facades\Blade::class,
    'Broadcast' => Illuminate\Support\Facades\Broadcast::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,
    'Lang' => Illuminate\Support\Facades\Lang::class,
    'Log' => Illuminate\Support\Facades\Log::class,
    'Mail' => Illuminate\Support\Facades\Mail::class,
    'Notification' => Illuminate\Support\Facades\Notification::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,
    'Str' => Illuminate\Support\Str::class,
    'URL' => Illuminate\Support\Facades\URL::class,
    'Validator' => Illuminate\Support\Facades\Validator::class,
    'View' => Illuminate\Support\Facades\View::class,

],

Now let's create a new class in App/Facades/TwitterFacade.php and put the following content

namespace App\Facades;

use Illuminate\Support\Facades\Facade;

class TwitterFacade extends Facade 
{
    protected static function getFacadeAccessor()
    {
        return 'twitter-poster';
    }
}

notice that we are extending Facade from Illuminate namespace and then we implemented getFacadeAccessor. we choose 'twitter-poster' as the name of the Twitter object that we want to use.

Now let's jump to the AppServiceProvider to bind the 'twitter-poster' to Twitter. in AppServiceProvider at Register method add the following

use DG\Twitter\Twitter;

public function register()
{
    $this->app->bind('twitter-poster',function(){
        $config = config('services.twitter');
        return new Twitter($config['api_key'], $config['api_secret'], $config['api_token'], $config['api_token_secret']);
    });
}

Now you can see the connection. first, we registered 'twitter-poster' and bind it to an instance of a Twitter class.

The final usage of our facade will be like following

Route::get('/tweet',function(){

    \App\Facades\TwitterFacade::send('Hello from ahmedash.com: Facade design pattern article');

});

Conclusion

We learned what is Facade and what problem does it solve and how to use it with Laravel

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原文地址：https://dev.to/ahmedash95/design-pattern...

译文地址：https://learnku.com/laravel/t/41695