SPRING COOKBOOK

Chapter 2. Defining Beans and Using Dependency Injection

In this chapter, we will cover the following recipes:

• Defining a bean explicitly with @Bean
• Defining a bean implicitly with @Component
• Using a bean via dependency injection with @Autowired
• Using a bean directly
• Listing all beans
• Using multiple configuration classes

Introduction

Beans are at the core of Spring. They are standard Java objects instantiated and managed by Spring.

Beans are mostly used to:

• Configure Spring in some way (database connection parameters, security, and so on)
• Avoid hardcoding dependencies using dependency injection, so that our classes remain self-contained and unit testable

In this chapter, you'll learn how to define beans and use them.