Spring & Guice DI

Spring

The way to use @Autowired and register beans:

@Component	simple bean
@Controller	servlet control ben
@Repository	DAO classes
@Configuration	general bean
XML file	define bean from xml

Also use @Bean to register a bean on method level.

@ComponentScan to detects and instantiates annotated components automatically

Guice

@Inject instead of @Autowired

@Provides instead of @Bean

Governator plugin instead of @ComponentScan

Guice Injection Styles

LOCATION	INJECTION ORDER	MOTIVATION	COMMENT
Constructor	First	Class immutability1 Mandatory dependencies	Only one allowed with @Inject.
Field	Second	Quick prototyping Code that doesn’t need testing	Injection order is random.
Setter	Third	Dealing with legacy classes Optional dependencies2	Injection

More info:

https://www.baeldung.com/guice-spring-dependency-injection
https://www.amazon.com/Google-Guice-Lightweight-Dependency-Firstpress/dp/1590599977