Spring Interview questions and Answers

Spring is one of the most popular open source app development frameworks for enterprise-class Java. Spring is lightweight in terms of size. Some of its core features can be used to develop any Java application, and there are in-built extensions on top of the Java EE platform for building web applications. Spring Framework is called a one-stop platform for building enterprise-level Java applications.

Following are the benefits of using Spring Framework:

• Enables developers to use POJO to build enterprise-class applications
• Simpler testing processes
• MVC framework provides good alternative to other frameworks, like Struts
• Convenient API translates technology-specific exceptions
• Lightweight IoC containers
• Consistent transaction management interface

Dependency Injection or DI is a design pattern that implements inversion or change of control for resolving dependencies. It is a process through which objects define their dependencies. Transferring the task of creating objects to someone else and using the dependency is called dependency injection. It can be done in 2 ways: constructor-based DI and setter-based DI.

Spring framework has 7 modules.

• The Core container module
• Application context module
• AOP module (Aspect Oriented Programming)
• JDBC abstraction and DAO module
• O/R mapping integration module (Object/Relational)
• Web module
• MVC framework module

Aspect-oriented programming or AOP is a programming approach that allows different properties of a program to determine how they are compiled into a program. You can use AOP with object-oriented programming or OOP.

Spring provides 2 types of containers:

• Spring BeanFactory Container : It provides basic support for DI and is defined by org.springframework.beans.factory.BeanFactory interface. BeanFactory and related interfaces are available in Spring for backward compatibility with third-party frameworks.
• Spring ApplicationContext Container : It adds enterprise-specific functionalities to interested event listeners. It is defined by org.springframework.context.ApplicationContext interface.

BeanFactory is the container that instantiates, manages and configures beans. Beans usually collaborate with each another and share dependencies, which are shown in the data used by the BeanFactory.

The ApplicationContext is the interface within a Spring application for offering configuration information to the application.