Demystifying Spring’s Application Context: Where Beans Come to Life

In Spring, the application context is responsible for managing the lifecycle of beans, including creating bean instances, wiring dependencies (dependency injection), and providing access to these beans throughout the application.

When a class is registered as a Spring bean, the following happens:

1. Bean Instantiation: Spring creates an instance of the class using its default constructor or other techniques like constructor injection or static factory methods.
2. Dependency Injection: If the bean has dependencies (e.g., DatabaseAccountService depends on AccountRepository), Spring will automatically inject the required dependencies into the bean instance.
3. Bean Registration: The instantiated bean is registered with the application context, typically by a unique identifier (often the bean class name with a lowercase first letter, e.g., databaseAccountService and databaseAccountRepository).
4. Bean Management: The application context manages the lifecycle of the bean, including calling any initialization and destruction methods defined for the bean.

By registering a class as a Spring bean, it becomes part of the Spring application context, and you can access and use its instances throughout your application. This is typically done by injecting the bean into other components that require it (e.g., injecting AccountRepository into DatabaseAccountService) or by retrieving the bean from the application context using methods like getBean().

The application context acts as a central repository for all the beans in your application, providing a consistent way to create, configure, and wire dependencies between objects. This promotes loose coupling, testability, and modularity in your codebase.

So, when I say that DatabaseAccountService and DatabaseAccountRepository will be automatically registered as Spring beans in the application context, it means that instances of these classes will be created, configured, and managed by the Spring container, making them available for use throughout the application as needed.

Effortless Bean Registration with @ComponentScan in Spring Boot

When I say that the DatabaseAccountService and DatabaseAccountRepository classes will be automatically registered as Spring beans in the application context, I mean that instances of these classes will be created and managed by the Spring container (also known as the application context or IoC container).

In Spring, the application context is responsible for managing the lifecycle of beans, including creating bean instances, wiring dependencies (dependency injection), and providing access to these beans throughout the application.

When a class is registered as a Spring bean, the following happens:

1. Bean Instantiation: Spring creates an instance of the class using its default constructor or other techniques like constructor injection or static factory methods.
2. Dependency Injection: If the bean has dependencies (e.g., DatabaseAccountService depends on AccountRepository), Spring will automatically inject the required dependencies into the bean instance.
3. Bean Registration: The instantiated bean is registered with the application context, typically by a unique identifier (often the bean class name with a lowercase first letter, e.g., databaseAccountService and databaseAccountRepository).
4. Bean Management: The application context manages the lifecycle of the bean, including calling any initialization and destruction methods defined for the bean.

By registering a class as a Spring bean, it becomes part of the Spring application context, and you can access and use its instances throughout your application. This is typically done by injecting the bean into other components that require it (e.g., injecting AccountRepository into DatabaseAccountService) or by retrieving the bean from the application context using methods like getBean().

The application context acts as a central repository for all the beans in your application, providing a consistent way to create, configure, and wire dependencies between objects. This promotes loose coupling, testability, and modularity in your codebase.

So, when I say that DatabaseAccountService and DatabaseAccountRepository will be automatically registered as Spring beans in the application context, it means that instances of these classes will be created, configured, and managed by the Spring container, making them available for use throughout the application as needed.