Java Configuration

Question 1

What does @Configuration do?

Answer 1

It tells spring it has bean-definitions (methods) in the class.

Question 2

What does @Bean mean

Answer 2

The @Bean annotation is used to indicate that a method instantiates, configures, and initializes a new object to be managed by the Spring IoC container

Question 3

True or false? The bean name is the same as the @Bean methodName()

Answer 3

True

Question 4

How can you access a Bean?

Answer 4

get the application context and then .getBean(<Methodname>) and cast it to right reference type.</Methodname>

e.g.

ApplicationContext context = SpringApplication.run(<className>)</className>

<AClassName> className = (<AclassName>) context.getBean(<method/beanName>);
</AclassName></AClassName>

Question 5

True/False - Spring configuration is completely decoupled from business logic?

Answer 5

True

Question 6

In what order does the Application Context

Answer 6

1. dataSource (the database)
2. the repository
3. the service

Question 7

In What environment can you create the spring context?

Answer 7

Basically in any context
e.g.

• Standalone application
• Web application
• Junit test

Question 8

How can you create the application context from multiple configurations?

Answer 8

When a configuration class become to big you can split it up. You can again combine them by using @Import.

e.g.

@Configuration
@Import({configOne.class, configTwo.class})
public class InfraConfiguaration {
….
}

Question 9

What is the default scope of a bean?

Answer 9

A singleton (design pattern)

Question 10

How can you change the scope of the bean?

Answer 10

by adding @Scope to the bean

Question 11

What are the 4 most used bean scopes?

Answer 11

• Singleton: a single instance is used
• prototype: a new instance is created each time a bean is referenced
• session : a new instance is create once per user session (web app only)
• Request: a new instance is created once per request (webapp only)