Spring

1. What is Spring

• lightweight jar libraries
• container (manages lifecycle of objects) (there is no need to use new for creating objects. All objects are in container)
• framework (there are a lot of classes which can help with data base, services)
• Dependency Injection (Inversion of Control) (objects get their their dependencies and do not create it)
• AOP (Aspect Oriented Programming)

2. How to inject information in bean: by constructor ; by getters and setters

In class Client create construstor :

    public Client(String name, String ID) {

        this.fullName = name;

        this.id = ID;

    }

<bean id="client" class="ua.epam.spring.core.beans.Client">

<constructor-arg value="John Smith"/>

<constructor-arg value="1"/>

</bean>

3. How to inject beans in each other. Use ref:

        <bean id="app" class="ua.epam.spring.core.App"/>

<constructor-arg ref="client"/>

<constructor-arg ref="eventLogger"/>

</bean>

4. There are two types of containers in Spring:

- BeanFactory (simple container that supports only DI)

- ApplicationContext (supports DI and frameword services

ClassPathXmlApplicationContext 

FileSystemXmlApplicationContext

AnnotationConfigApplicationContext

XmlWebApplicationContext 

StaticApplicationContext)

5. How to create context
ApplicationContext ctx = new ClassPathXmlApplicationContext( "spring.xml");
App app = (App) ctx.getBean("app");
app.logEvent("Some event for 1");