Spring Framework is the most trusted and widely used application development framework in Enterprise Java. Originally introduced as a simple and lightweight alternative for the complex J2EE, Spring has now grown to become a truly modern application development platform. Spring and its subprojects provide an excellent foundation for end-to-end application development, with features beyond even those provided by the latest Java EE, such as mobile development, social networking, and big data, besides traditional Java web, server-side, or even standalone applications. After more than a decade since its inception, Spring continues to inspire technologies and technologists across the globe.
Although Spring simplifies Java development drastically, software developers and architects are still required to gain a thorough understanding of its core concepts and features in order to deduce the best use of the Spring family. The simplicity Spring offers to otherwise complex Java development is the result of smart abstractions that it provides in the form of excellent APIs and modules. Spring components relieve the developer of all the technical complexity and heavy lifting of common technical and infrastructure plumbing tasks. As the official Spring documentation says, Spring provides comprehensive infrastructure support so that you can focus on your application.
This book is an attempt to make your Spring learning even easier and a more enjoyable experience.
This chapter gives you a solid foundation of the core Spring Framework, guiding you through its core concepts, components, and modules accompanied by relevant sample code snippets that illustrate the best and most practical usage of each feature in order to solve your everyday programming problems.
In this chapter, we will cover the following topics:
- The Spring landscape
- Setting up the development environment
- Your first Spring application
- Core concepts
- The IoC (Inversion of Control) container
- Beans in detail
- Working with bean definition profiles
- Handling resources
- SpEL (Spring Expression Language)
- Aspect Oriented Programming
Spring covers a wide variety of technological aspects handled by applications of different types, ranging from a simple standalone Java application up to the most complex, mission critical distributed enterprise systems you can imagine. Unlike most other open source or proprietary frameworks that focus on a specific technology concern such as Web, Messaging, or Remoting, Spring successfully covers almost all the technical aspects of business applications. In most cases, instead of reinventing solutions, Spring utilizes and integrates proven existing frameworks to achieve this end-to-end coverage. Spring is highly modular; hence, it noninvasively allows you to cherry-pick just the modules or features you require in order to become a one-stop shop for all your development needs on JVM.
The whole Spring Framework portfolio is organized into three major elements:
- Spring Framework
- Spring Tool Suite
- Spring subprojects
Spring is constantly improving and becoming more and more modular with every new version so that you can use just the required modules.
The core Spring Framework provides basic infrastructure for Java development on top of its core Inversion of Control (IoC) container. The IoC container is an infrastructure that provides Dependency Injection (DI) for applications. Both the concepts of Dependency Injection and IoC containers are explained in detail later in this chapter. The core Spring Framework is divided into the following modules, providing a range of services:
|
Module |
Summary |
|---|---|
|
Core container |
Provides the IoC and Dependency Injection features. |
|
AOP and instrumentation |
Provides AOP Alliance compliant features for weaving cross-cutting concerns in Spring applications. |
|
Messaging |
Provides messaging abstraction over the Spring Integration project for messaging-based applications. |
|
Data access/integration |
The data-access/integration layer consists of JDBC, ORM, OXM, JMS, and transaction modules. |
|
Web |
Web technology abstraction over Spring MVC, web socket, and portlet APIs. |
|
Test |
Unit testing and integration testing support with JUnit and TestNG frameworks. |
STS is an Eclipse-based IDE (short for Integrated Development Environment) for Spring development. You can download the pre-bundled STS from http://spring.io/tools/sts/all or update your existing Eclipse installation from the update site found at the same location. STS provides various high-productivity features for Spring development. In fact, a Java developer can use any IDE of their choice. Almost all the Java IDEs support Spring development, and most of them have got plugins available for Spring.
Spring has many subprojects that solve various application infrastructure needs. From configuration to security, web apps to big data, productivity to enterprise application integration (EAI), whatever your technical pain point be, you will find a Spring project to help you in your application development. Spring projects are located at http://spring.io/projects.
Some notable projects you may find useful right away are Spring Data (JPA, Mongo, Redis, and so on), Spring Security, Spring Web Services, Spring Integration, Spring for Android, and Spring Boot.