Java 9 Dependency Injection

By : Nilang Patel , Krunal Patel

4 (3)

Buy this Book

Java 9 Dependency Injection

4 (3)

By: Nilang Patel , Krunal Patel

Buy this Book

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.

Free Chapter

Why Dependency Injection?

Design patterns

Dependency Inversion Principle

Inversion of Control

Dependency injection

IoC containers

Summary

Dependency Injection in Java 9

Java 9 introduction

Modular Framework in Java 9

Dependency Injection using the Java 9 Modular Framework

Summary

Dependency Injection with Spring

A brief introduction to Spring framework

Bean management in Spring container

Dependency Injection (DI) in Spring

Auto-wiring in Spring

Annotation-based DI

DI with Java configuration

Summary

Dependency Injection with Google Guice

A brief introduction to the Google Guice framework

Basic injection in Guice

Binding in Guice

Guice injection

Summary

Scopes

Introduction to bean scopes in Spring

How to define a bean scope

Dependency injection and the bean scope

How to choose a bean scope

Scopes in Google Guice

Summary

Aspect-Oriented Programming and Interceptors

AOP introduction

Spring AOP

Choosing AOP frameworks and style of configuration

Summary

IoC Patterns and Best Practices

Various patterns to achieve IoC

Configuration styles

Injection using the setter method versus the constructor

Circular dependency

Best practices and anti-patterns

Summary

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How to choose a bean scope

Each scope in Spring has a different feature, and it falls to us as programmers to know how to utilize those scopes.

In an application, if we have a stateless object and there is no impact on the object creation process then the use of a scope is unnecessary. In contrast, if an object has state then it is advisable to use a scope such as singleton.

When dependency injection is in business, then the singleton scope is not adding much value. In spite of the fact that singletons spare object creation (and afterward garbage collection), synchronization requires us to initialize a singleton bean. Singletons are most valuable for: