Book Image

Java 9 Dependency Injection

By : Nilang Patel, Krunal Patel
Book Image

Java 9 Dependency Injection

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

Chapter 1. Why Dependency Injection?

In software development, very often someone else might already have found effective solutions to the problems you are facing.

As a developer, you don't need to reinvent the wheel every time. Instead, you need to refer to the well-established practices and methodologies. Have you guessed what we are talking about? That's correct: design patterns.

This chapter is crafted to cover the following interesting topics:

  • What design patterns are and their benefits
  • Dependency Injection Principle (DIP)
  • Inversion of Control (IoC)—a design methodology to implement DIP
  • Various design patterns to implement IoC
  • Dependency Injection (DI)
  • Various types to implement DI
  • How an IoC container is helpful to apply a DI