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.
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