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This article mainly introduces the relevant knowledge of "how to use laravel to achieve dependency injection in php". The editor shows you the operation process through an actual case. The operation method is simple, fast and practical. I hope this article "how to use laravel to achieve dependency injection in php" can help you solve the problem.

The laravel container contains control inversion and dependency injection. To use it, you can bind the object first and use make to fetch it directly when needed.

Usually our call is as follows.

$config = $container- > make ('config'); $connection = new Connection ($this- > config)

It is easy to understand that this advantage is that there is no need to directly new an instance, the method value has not changed, and the instance can be shared in many places.

But what does this have to do with dependency injection? the real dependency injection does not need to pass any parameter values to the method, but only needs to specify the method parameter type, and the code automatically looks up the relationship and relies on automatic injection.

This feature can be reflected in laravel's Controller, Job, and so on, as follows:

Class TestController extends Controller {public function anyConsole (Request $request, Auth $input) {/ / todo}}

Let's take a look at how he implements automatic dependency injection:

Kernel is called by index.php, through multi-layer Kernel pipeline, and then to Router, through multi-layer middleware pipeline. Finally locate to

Line 124 of Illuminate/Routing/Route.php.

Public function run (Request $request) {$this- > container = $this- > container?: new Container;try {if (! Is_string ($this- > action ['uses']) {return $this- > runCallable ($request);} if ($this- > customDispatcherIsBound ()) {return $this- > runWithCustomDispatcher ($request);} return $this- > runController ($request);} catch (HttpResponseException $e) {return $e-> getResponse ();}}

Determine whether $this- > action ['uses'] (format lines such as:\ App\ Http\ Controller\ Datacenter\ RealTimeController@anyConsole) is a string, and $this- > customDispatcherIsBound determines whether a user-defined route is bound. Then jump to $this- > runController ($request).

Protected function runController (Request $request) {list ($class, $method) = explode ('@', $this- > action ['uses']); $parameters = $this- > resolveClassMethodDependencies ($this- > parametersWithoutNulls (), $class, $method); if (! Method_exists ($instance = $this- > container- > make ($class), $method)) {throw new NotFoundHttpException;} return call_user_func_array ([$instance, $method], $parameters);}

The method $this- > resolveClassMethodDependencies can tell from the name that it is the one we are looking for. $this- > parametersWithoutNulls () is to filter empty characters, and $class and $method lines such as:\ App\ Http\ Controller\ Datacenter\ RealTimeController and anyConsole, respectively.

Protected function resolveClassMethodDependencies (array $parameters, $instance, $method) {if (! Method_exists ($instance, $method) {return $parameters;} return $this- > resolveMethodDependencies ($parameters, new ReflectionMethod ($instance, $method);}

New ReflectionMethod ($instance, $method) is the reflection object that gets the class method, see documentation: http://www.php.net/manual/zh/class.reflectionmethod.php

Next jump to line 54 of Illuminate/Routing/RouteDependencyResolverTrait.php.

Public function resolveMethodDependencies (array $parameters, ReflectionFunctionAbstract $reflector) {$originalParameters = $parameters;foreach ($reflector- > getParameters () as $key = > $parameter) {$instance = $this- > transformDependency ($parameter, $parameters, $originalParameters); if (! Is_null ($instance) {$this- > spliceIntoParameters ($parameters, $key, $instance);}} return $parameters;}

The class parameter array is obtained by reflecting the class method, and then traversed and passed to the $this- > transformDependency method. If the instance is not available, call $this- > spliceIntoParameters to know the parameter.

Protected function transformDependency (ReflectionParameter $parameter, $parameters, $originalParameters) {$class = $parameter- > getClass (); if ($class & &! $this- > alreadyInParameters ($class- > name, $parameters)) {return $this- > container- > make ($class- > name);}}

I finally see the shadow of the container, and it is true that the final object is extracted through the container's make method. At this point, the parameters are constructed and will eventually be called back by the call_user_func_array of the runController method.

That's all for "how to use laravel to implement dependency injection in php". Thank you for reading. If you want to know more about the industry, you can follow the industry information channel. The editor will update different knowledge points for you every day.

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