m0jDI - Java Dependency Injection Library

m0jDI a very simple, lightweight dependency injection library for Java, designed to simplify object creation and dependency management. It supports automatic handling of singletons and non-singleton classes using annotations.

Features

• Singleton Support: Automatically manage singleton instances using the @Singleton annotation.
• Constructor Injection: Inject dependencies via constructors annotated with @Inject.
• Field Injection: Inject dependencies into fields annotated with @Injected.

Installation

Add the library to your project using Gradle:

dependencies {
    implementation 'me.m0dii:m0jdi:1.0.0'
}

Usage

1. Mark Classes with Annotations

Use the @Singleton annotation to mark classes as singletons. Use the @Inject annotation for fields or constructors that require dependency injection.

Example:

@Singleton
public class Service {
    public void perform() {
        System.out.println("Service performed!");
    }
}

2. Set up Your Application

Create an InjectorContainer, register your classes, and use Injector to inject dependencies.

Example:

public class App {
    public static void main(String[] args) {
        InjectorContainer container = new InjectorContainer();
        container.register(Service.class); // Register your classes

        Service service = container.resolve(Service.class); // Resolve instance
        Injector injector = new Injector(container);
        injector.injectDependencies(service); // Inject dependencies if needed

        service.perform();
    }
}

3. Constructor Injection

Annotate the constructor with @Inject to automatically inject its dependencies. (Note: You must resolve the class via the container for constructor injection to work.)

Example:

public class Controller {
    private final Service service;

    @Inject
    public Controller(Service service) {
        this.service = service;
    }

    public void handleRequest() {
        service.perform();
    }
}

// Usage:
// container.register(Controller.class);
// Controller controller = container.resolve(Controller.class);
// injector.injectDependencies(controller);

4. Field Injection

Use the @Inject annotation on fields to inject dependencies. After resolving the instance, call injector.injectDependencies.

Example:

public class UserHandler {
    @Inject
    private Service service;

    public void processUser() {
        service.perform();
    }
}

// Usage:
// container.register(UserHandler.class);
// UserHandler userHandler = container.resolve(UserHandler.class);
// injector.injectDependencies(userHandler);