JarCastingfemto
Femto is a teeny-tiny dependency injection library written in pure standard Java.
Installing
Maven:
<dependency>
<groupId>uk.co.probablyfine</groupId>
<artifactId>femto</artifactId>
<version>${version}</version>
</dependency>
Gradle:
implementation "uk.co.probablyfine:femto:${version}"
Usage
class Example {
public static void main(String... args) {
// Initialise a new injector
var injector = new FemtoInjector();
// Bind a class
injector.bind(One.class);
// Bind a class to an implementing class
injector.bind(Two.class, TwoImplementation.class);
// Bind a class to an instance
injector.bindInstance(Three.class, new ThreeImplementation());
// Depends on One, Two, Three
injector.bind(Four.class);
// Create a new object
Four four = injector.get(Four.class);
}
}
Design Decisions
- Singleton by default: The first call to
FemtoInjector#getcaches the result for each class and returns the same value afterwards - Lazy by default:
FemtoInjectordoes not initialise any classes until.get()is called. - No annotation "magic": Clients register components directly with the injector rather than using JSR 330 (
@Inject) annotations. - Prefer standard Java over dependencies: Keeps the library small, and the source code easy to read.
- No named bindings: Usd the type system to extend and name classes instead.