Ravel - Java Dependency Injection Library

A lightweight and efficient Dependency Injection (DI) library for Java applications, designed for simplicity and flexibility.

Features

• Module-Based Dependency Management (Static and Dynamic Modules)

Limitations

This library is designed to be minimalistic and does not support the following features:

• Supertype Injections: Beans must be explicitly defined with their concrete types; injection by supertype or interface is not supported.
• Cyclic Dependencies: The library does not support cyclic dependencies. If a cycle is detected, an exception is thrown with no way to resolve it.

Installation

Add the following dependency to your pom.xml if using Maven:

<dependency>
    <groupId>com.github.tix320</groupId>
    <artifactId>ravel</artifactId>
    <version>0.4.0</version>
</dependency>

For Gradle:

dependencies {
    implementation 'com.github.tix320:ravel:0.4.0'
}

Architecture Overview

The library is structured around modules, which can be either dynamic or static. Each module contains a list of bean definitions.

Bean Definition Components

• Bean Key: A combination of the bean type and its qualifier.
• Scope: Either SINGLETON (one instance per injector) or PROTOTYPE (a new instance per injection point).
• Dependencies: Other beans, represented by their Bean Keys.
• Factory Method: A function that accepts dependencies and creates an instance of the bean.

Types of Modules

1. Static Modules: Defined declaratively by a class with annotated factory methods.
2. Dynamic Modules: Built programmatically, allowing logic-driven bean definitions rather than declarative configurations.

Static and dynamic modules can be used together within the same injector.

Quick Start

Defining a Static Module with Annotations

@RequireModules(statics = {ModuleB.class})
public class ModuleA {
    
    @Singleton
    public BeanA a(BeanB b) {
        return new BeanA(b);
    }
}

public class ModuleB {
    
    @Singleton
    public BeanB b() {
        return new BeanB();
    }
}

Defining a Dynamic Module

var beanDefinition = new BeanDefinition(
    new BeanKey(BeanB.class), Scope.SINGLETON,
    List.of(), dependencies -> new BeanB()
);

DynamicModuleDefinition dynamicModule = new DynamicModuleDefinition(
    "dynamic", List.of(), List.of(beanDefinition)
);

Using Static and Dynamic Modules Together

Injector injector = new Injector();
injector.registerModule(ModuleA.class);
injector.registerDynamicModule(dynamicModule);
injector.build();

BeanA beanA = injector.inject(BeanA.class);

Versioning

This project follows Semantic Versioning.

License

Ravel is released under the Apache License, Version 2.0.

Contact

• Author: tix320