Hi Everyone , I am new to learning Spring Framework and have started to write about the topics I am learning , sharing them here about the same.
This blogs talks about
Spring Bean
Sprint Context
If you're diving into the Spring Framework, you've probably encountered terms like Spring Bean, Spring Container, and ApplicationContext. These concepts are the foundation of what makes Spring so powerful and flexible. Think of them as the essential building blocks for your modern Java application.
🧱 What is a Spring Bean?
In the Spring world, a Bean is simply a Java object that is instantiated, assembled, and managed by the Spring Container.
POJO with a twist: A bean is essentially a Plain Old Java Object (POJO) that Spring manages.
Managed Lifecycle: Spring controls the entire lifecycle of a bean, from its creation and initialization to the injection of its dependencies and eventual destruction.
Definition: You tell Spring which classes should become beans using configuration (like the @Component, @Service, or @Controller annotations, or Java/XML configuration).
Why use a Bean? It's all about Inversion of Control (IoC) and Dependency Injection (DI). Instead of manually creating objects (new MyService()), you declare your class as a bean, and Spring handles the heavy lifting of creation and linking it with other beans. This leads to loosely coupled, more testable code.
📦 What is the Spring Container?
The Spring Container is the core engine of the Spring Framework. Its main responsibility is managing the Spring Beans.
The Manager: It's like a central factory or manager for your application's components.
IoC Implementation: The container embodies the principle of Inversion of Control (IoC), which means it takes over the control of object creation and dependency management from your application code.
The Blueprint Reader: The container reads your configuration metadata (annotations, XML, or Java config) to learn which objects to instantiate, configure, and wire together.
The Spring Container is an interface, with two main implementations: BeanFactory (the simpler, base container) and ApplicationContext.
🌐 What is ApplicationContext (The Preferred Container)?
The ApplicationContext is the modern and enhanced version of the Spring Container, and it's the one you'll almost always use in Spring Boot applications.
Superset of the Container: The ApplicationContext is a sub-interface of the BeanFactory and is considered a complete superset, meaning it offers all the features of the basic container and much more.
Enterprise Features: It adds crucial enterprise-level functionality:
Internationalization (I18N): Support for resolving text messages in different languages.
Event Publication: The ability to publish events to beans registered as listeners.
Eager Initialization: By default, it creates all singleton beans upon startup, ensuring the application is ready to go immediately (unlike BeanFactory, which is lazy).
Easier AOP Integration: Better integration with Aspect-Oriented Programming features.
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