Spring Framework- Basics

The question which I asked 4 years back when I was to use Spring framework for project was- Why Spring? I was using Struts for few years and was in love that, so why to try something new.

Over the time I have found a very convincing answer which I will share.

    1.Empowering POJO’s
    2.Dependency Injection
    3.It is more than web application development framework
    4.Support for Aspect oriented programming

1. For me most important feature which Spring provides is use of POJOs (Plain Old Java Objects). Working with frameworks like Struts, you need to follow a very strict format, for example for each controller servlet you need to extend action class and override execute method with fixed number of parameters. Even if you are creating simple servlet you need to have get and post methods to handle client requests in a particular format. Spring finally gives you freedom to use plain java classes and convert to controllers or request handlers using simple annotations.

2. Dependency injection is implementation of inversion of control principle which helps maintain loose coupling and move away dependencies from the current class and let it focus on its real goal. Read more on dependency injection-http://kamalmeet.com/2012/03/dependency-injection-simplified/, http://kamalmeet.com/2013/03/more-on-dependency-injection/, http://kamalmeet.com/2013/03/spring-implementation-of-dependency-injection/

3. As I said, Spring is not just for handling request response or implementing MVC like struts, it goes much beyond that. It is kind of a bouquet providing end to end solution for an application like it provides Spring Security for controlling access to application, provides Spring MVC for handling request/ response in MVC mode, provide Workflow to handle control flow, support for webservices through Spring Restful templates etc.

4. Finally support for aspect oriented programming (AOP). Spring supports AOP, that means you can separate some aspects of code so that your classes can focus on the responsibility given to them. For example creating logs is one aspect of a code, which we need to write in every class to make sure proper logs are maintained. Spring helps you pull this aspect out of the code and handle through some configuration making sure logging occurs whenever required.