Spring is great framework for development of Enterprise grade applications. Spring is a light-weight framework for the development of enterprise-ready applications. It provides very simple and rich facilities to integrate various frameworks, technologies, and services in the applications. One of the main reason for using the Spring framework is to keep code as simple as possible. It push the way to develop enterprise applications with loosely coupled simple java beans. For this reason, the spring framework can also be called a Plain Old Java Object (POJO) framework.
Spring is an open-source framework developed by Spring Source, a division of VMware. Spring frame work can summarized in two ways.
- Container-Spring framework can be described as a light weight container, as it does not involve installation, configuration, start and stop activities associated with a container. It is just a simple collection of few Java ARchive (JAR) files that need to be added to the classpath. The Spring Container takes the classes in the application, creates objects, and manages the life cycle of those objects.
- Framework-Spring framework can be described as an Application Programming Interface(API) containing a large collection of the classes, methods, interfaces, annotations, XML tags that can be used in an application. The API provides a variety of factory and facade classes that help you to use any framework or functionality very easily in your application.
Data Access Using Java Database Connectivity (JDBC): The Spring framework provides a rich support for working with JDBC. A typical JDBC code involves plumbing works, such as creating connection, statements, executing queries and handling exceptions for performing database operations.Spring framework provides a set of classes that take care of these core JDBC operations.
Data Access Using Object Relational Mapping (ORM): There are lots of ORM frameworks, such as Hibernate, Toplink, iBatis etc that can be used in Java Applications. Spring framework provides lots of classes that makes working with ORM is very easy.
Aspect Oriented Programming (AOP): One of the main paradigms that spring uses to provide enterprise services for your applications is AOP. AOP is a mechanism by which you can introduce functionality in your existing code without modifying your design. In short we can say AOP is used to weave cross-cutting functionalities or aspects into the code. The Spring framework uses AOP provides various enterprise services such a transaction and security in an application.
Core Spring Framework: The
Core package is the most fundamental part of the framework and provides the
IoC and
Dependency Injection features. The basic concept here is the
BeanFactory, which provides a sophisticated implementation of the factory pattern which removes the need for programmatic singletons and allows you to decouple the configuration and specification of dependencies from your actual program logic.
Spring's MVC: Spring MVC package provides a Model-View-Controller (MVC) implementation for web-applications. Spring's MVC framework is not just any old implementation; it provides a
clean separation between domain model code and web forms, and allows you to use all the other features of the Spring Framework.
Object XML Mapping: Spring 3.0 introduces the OXM module that was earlier not a part of the core framework. OXM is a mechanism that marshals or converts object into the XML format and vice versa. There are lots of OXM frameworks, such as Caster, Xstream, JiBX, Java API for XML Binding(JAXP), and XMLMeabs. Spring 3.0 provides a uniform API to access any of these OXM frameworks for marshalling and unmarshalling object and XML.
Dependency Injection (DI): The technology that Spring is most identified with is the
Dependency Injection (DI) flavor of Inversion of Control. The Inversion of Control (IoC) is a general concept, and it can be expressed in many different ways and Dependency Injection is merely one concrete example of Inversion of Control.
What is dependency injection exactly? Let's look at these two words separately. Here the
dependency part translates into an association between two classes. For example, class
X is dependent on class
Y. Now, let's look at the second part,
injection. All this means is that class
Y will get injected into class
X by the IoC. Here we don't need to write lots of code to create the instance of the dependent classes.
Dependency injection promotes loose coupling . It paves the way for the removal of the usal factory and utility classes that we write in our applications.
Look Following:
- The DAO classes use Data Sources which can be injected into them
- The Service classes may need to add few java beans
Dependency Injection is also known as Inversion of Control or IoC. Ioc refers to the control of creating instances being done by the Spring Container. The control for creating and constructing objects is taken care by the container. The container creates objects and injects then into our applications.
Benefits of Using Spring Framework:
Following is the list of few of the great benefits of using Spring Framework:
- Spring enables developers to develop enterprise-class applications using POJOs. The benefit of using only POJOs is that you do not need an EJB container product such as an application server but you have the option of using only a robust servlet container such as Tomcat or some commercial product.
- Spring is organized in a modular fashion. Even though the number of packages and classes are substantial, you have to worry only about ones you need and ignore the rest.
- Spring does not reinvent the wheel instead, it truly makes use of some of the existing technologies like several ORM frameworks, logging frameworks, JEE, Quartz and JDK timers, other view technologies.
- Testing an application written with Spring is simple because environment-dependent code is moved into this framework. Furthermore, by using JavaBean-style POJOs, it becomes easier to use dependency injection for injecting test data.
- Spring's web framework is a well-designed web MVC framework, which provides a great alternative to web frameworks such as Struts or other over engineered or less popular web frameworks.
- Spring provides a convenient API to translate technology-specific exceptions (thrown by JDBC, Hibernate, or JDO, for example) into consistent, unchecked exceptions.
- Lightweight IoC containers tend to be lightweight, especially when compared to EJB containers, for example. This is beneficial for developing and deploying applications on computers with limited memory and CPU resources.
- Spring provides a consistent transaction management interface that can scale down to a local transaction (using a single database, for example) and scale up to global transactions (using JTA, for example).