A brief introduction to service providers and facade patterns in Laravel

This article mainly introduces you to the relevant information about the use of service providers and facade patterns in Laravel. The article introduces you to the service providers and facade patterns in Laravel through detailed example codes. It will be helpful for your study or The work has certain reference and learning value. Friends who need it can study together.

Preface

In laravel, when we may need to use the classes we added, we can create a folder specifically to store class files. You can also use Laravel's service provider.

In fact, there is not much difference between the two. The main reason is that if the former is used, it will depend on the business code. Imagine if a controller references many custom class files, then you can imagine what will happen. How many dependencies are generated, so we can use the service provider method to register classes in the laravel container. In this case, dependencies can be managed in a separate configuration file, and logic and later maintenance will be much more convenient.

Using facades is mainly because you don’t need to instantiate a class. You can use static methods to access class methods, which is more convenient to use. However, this actually has disadvantages, such as not being able to jump directly to the corresponding Inside the method, it is not possible to intuitively understand the usage of this method. Personal development may not have much impact, but if it is developed by a team, it may be a bit dizzying to use it.

Taking the file system that comes with Laravel as an example, a service provider is registered in the providers array of the configuration file in config/app.php:

Illuminate\Filesystem\FilesystemServiceProvider::class,

A facade is defined in the alias array:

‘File' => Illuminate\Support\Facades\File::class,

Through these two steps, we can use Laravel very conveniently File system related operations, and the calling form is very simple, such as:

• File::exist($path) to determine whether the file exists.

• File::get($path, $lock = false), get the contents of a file.

• File::append($path, $data), append the content to the end of a file.

• File::files($directory), get all the files in a directory.

So how is this done? Let’s talk about Laravel’s service provider and facade mode respectively.

Service provider

Let’s take a look at the definition first:

The service provider is the center where all Laravel applications are started. . All core Laravel services, including your own applications, are started through service providers.

In the file system service provider, located at /vendor/laravel/framework/src/Illuminate/Filesystem/FilesystemServiceProvider.php, the register method can see that a singleton is bound:

protected function registerNativeFilesystem()
{
 $this->app->singleton('files', function () {
  return new Filesystem;
 });
}

This singleton is the singleton mode of the Filesystem class. Of course, this service provider can also bind other singletons or do more things. We only study the principle of File::exist() here.

So there is a single instance of files, which is actually an instance of the Filesystem class.

At this time, if there is no Facade, you can also call the method of the Filesystem instance, that is, call it like this:

app(‘files')->exist($path)

Okay , now let’s talk about Facade.

Facade facade mode

Let’s take a look at the introduction first:

Facades /fəˈsäd/ is the application The classes available in the application's service container provide a "static" interface. Laravel comes with many facades that can be used to access almost all of its services. Laravel facades are "static proxies" for base classes in the service container. Compared with traditional static method calls, facades provide a simpler and richer syntax, while also having better testability and scalability.

At the beginning of this article, we mentioned that the alias array defines a File. The specific class is

Illuminate\Support\Facades\File::class,

Its content is:

class File extends Facade
{
 /**
  * Get the registered name of the component.
  *
  * @return string
  */
 protected static function getFacadeAccessor()
 {
  return 'files';
 }
}

It actually returns a name. Note that the name files is the name of the singleton mode just bound? That's right.

In this way, you can use the File alias or facade to call methods in this Filesystem instance.

Through this article, I hope everyone can understand the relationship between service providers, Facade, and instances of the actually called classes.

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