Book Image

Java 9 Dependency Injection

By : Nilang Patel, Krunal Patel
3 (1)
Book Image

Java 9 Dependency Injection

3 (1)
By: Nilang Patel, Krunal Patel

Overview of this book

Dependency Injection (DI) is a design pattern that allows us to remove the hard-coded dependencies and make our application loosely coupled, extendable, and maintainable. We can implement DI to move the dependency resolution from compile-time to runtime. This book will be your one stop guide to write loosely coupled code using the latest features of Java 9 with frameworks such as Spring 5 and Google Guice. We begin by explaining what DI is and teaching you about IoC containers. Then you’ll learn about object compositions and their role in DI. You’ll find out how to build a modular application and learn how to use DI to focus your efforts on the business logic unique to your application and let the framework handle the infrastructure work to put it all together. Moving on, you’ll gain knowledge of Java 9’s new features and modular framework and how DI works in Java 9. Next, we’ll explore Spring and Guice, the popular frameworks for DI. You’ll see how to define injection keys and configure them at the framework-specific level. After that, you’ll find out about the different types of scopes available in both popular frameworks. You’ll see how to manage dependency of cross-cutting concerns while writing applications through aspect-oriented programming. Towards the end, you’ll learn to integrate any third-party library in your DI-enabled application and explore common pitfalls and recommendations to build a solid application with the help of best practices, patterns, and anti-patterns in DI.
Table of Contents (14 chapters)
Title Page
Copyright and Credits
Packt Upsell
Contributors
Preface
Index

Chapter 3. Dependency Injection with Spring

So far, we have learned why modularity is so important in writing cleaner and maintainable code. In Chapter 1Why Dependency Injection?, we learned about the Dependency Inversion Principle (DIP), IoC (a design methodology to implement DIP), and various design patterns to implement IoC. Dependency Injection (DI) is one of the design patterns to achieve IoC.

In the Chapter 2, Dependency Injection in Java 9, we learned how modular framework and DI are facilitated in Java 9. In this chapter, we will continue our journey to learn DI in Spring—one of the most popular and widely used frameworks to implement enterprise applications.

In this chapter, we will explore the following topics:

  • A brief introduction to Spring framework
  • Bean management in Spring
  • How to achieve DI with Spring
  • Auto wiring: he feature of resolving dependency automatically
  • Annotation-based DI implementation
  • DI implementation with Java-based configuration