Spring Core Containers and Dependency Injection

Java classes should be as independent as possible from each other.

• To decouple classes from one another, dependencies should be injected through Constructors and Setters.
• Classes should not configure themselves. IoC uses dependency injection to: 
• Configure a class correctlyi from outside the class
• Wire services or components.
• Piecing together all the beans in the Spring Container is called Wiring.
• This can most commonly be don through xml.
• Various BeanFactories and ApplicationContext objects that support wiring include:
• XMLBeanFactory
• ClassPathXMLApplicationContext
• FileSystemXMLApplicationContext
• XMLWebApplicationContext