Annotations

Question 1

What is the difference between @Component, @Controller, @Repository & @Service annotations?

Answer 1

@Component: generic stereotype and can be used across application

@Controller: Used to annotate classes at presentation layer level like in spring MVC

@Service: used to annoate classes at a service layer level

@Repository: Used to annotate classes at a persistence layer that acts as a database repository

Question 2

What do you understand by @Required annotation?

Answer 2

• applied to bean property setter method
• indicates that at the configuration time the affected bean property should be populaed in XML configuration file, otherwise throw a BeanInitializationException

Question 3

What do you understand by @Autowired annotation

Answer 3

the @Autowired annotation provides more accurate control over where and how autowiring should be done. Th @Autowired annotation is used to autowire bean on setter methods, constructor, a property or methods with arbitrary names and/or multiple argumentos

Question 4

What do you understand by @RequestMapping annotation?

Answer 4

- can be applied at both levels:
class level: maps the URL of the request
Method level: maps the URL as well as HTTP request method