/custom-di

Custom Dependency Injection Kind of IOC

Primary LanguageJavaMIT LicenseMIT

custom-di

Custom Dependency Injection , kind of IOC

Custom made dependency Injection replicating the functionality of Spring IOC.

Design considerations :

  1. Core pattern we will use there is Dependency injection pattern
  2. Loosely coupled
  3. Logging
  4. Modularity
  5. Integrated Unit testing
  6. JDK 1.8 - target build

Limitations :

  1. Not a full plugged container
  2. No version backword compactability

Main Features

  • Create instance of your services
  • Automatically resolve dependencies
  • Create Beans
  • Add your own custom mapping annotations for services and beans
  • Manage instantiated services (get them by annotation, qualifier, type)
  • Reload instantiated services
  • Handle custom service and bean scopes by using proxies.

The Goal

This project is created with the purpose to help understand how DI/IoC Containers work.

How to run the app?

  • Run 'clean install' / 'mvn package' and get the generated jar file.
  • Import it into your project
  • In your main method call 'DepedentInjector.run(YourStartupClass.class);'
  • Annotate your startup class with @Service
  • Create a void method and annotate it with @StartUp

You can also run the app with 'DepedentInjector.run(YourStartupClass.class, new DependencyConfiguration());'.

Supported annotations by default:

  • Bean - Specify bean producing method.
  • Service - Specify service.
  • Autowired - Specify which constructor will be used to create instance of a service. also you can annotate fields with this annotation.
  • PostConstruct - Specify a method that will be executed after the service has been created.
  • PreDestroy - Specify a method that will be executed just before the service has been disposed.
  • StartUp - Specify the startup method for the app.DependencyInjector
  • AliasFor - You can use this annotation to integrate your own annotations with DependencyInjector AliasFor works with Autowired, NamedInstance, Nullable, PostConstruct, PreDestroy, Qualifier.
  • NamedInstance - Specify the name of the service / bean.
  • Nullable - required dependency can be null.
  • Qualifier - Specify the name of the dependency that you are requiring.
  • Scope - Specify the scope of the service. SINGLETON or PROTOTYPE

You can use the configuration to provide custom annotations that can act like @Bean and @Service.

The benefit of that is that you might have some services that you might want to filter out by something and custom annotations is a good approach.

Also you can access the DependencyContainer instance this way 'DependencyContainer dc = DependencyInjector.run(...)' or by requiring it from the startup method.

Documentation

Currently there is no real documentation from where you can read, but you can read the javadoc or you can check out the integration tests located https://github.com/nookashiva/custom-di-tests

More info

If you are having trouble running the app, contact me at nookashiva@gmail.com