In Spring Core, beans undergo a life cycle that consists of several key stages: instantiation, population of properties, initialization, and destruction. Understanding this life cycle is crucial for effectively managing beans within a Spring application. Let's delve into each stage of the bean life cycle along with the corresponding methods and annotations used in Spring Core.
1. Instantiation:
At this stage, Spring creates instances of beans defined in the application context.
Beans can be instantiated using constructor injection or factory methods.
No Spring-specific annotations are directly involved in this stage.
2. Population of Properties:
After instantiation, Spring injects dependencies and sets properties defined for the beans.
This stage involves the population of properties through setter methods or fields.
Annotations like `@Autowired` and `@Value` facilitate dependency injection and property population.
3. Initialization:
Initialization involves executing custom initialization logic before the bean is put into service.
Spring provides several ways to hook into the initialization process:
`@PostConstruct` method: Annotated methods are executed after dependencies have been injected and properties have been set.
Custom init method: Developers can define custom initialization methods and specify them in bean configuration using the `init-method` attribute
During this stage, beans can perform tasks such as setting up resources, establishing connections, or performing any necessary setup operations.
4. Destruction:
Destruction involves releasing resources and performing cleanup tasks before the bean is removed from the container.
Spring provides several mechanisms for bean destruction:
`@PreDestroy` method: Annotated methods are executed before the bean is destroyed.
Custom destroy method: Developers can define custom destruction methods and specify them in bean configuration using the `destroy-method` attribute.
During this stage, beans release resources, close connections, and perform any necessary cleanup operations.
Understanding the bean life cycle in Spring Core and leveraging annotations and interfaces provided by the framework enables developers to manage beans effectively, ensuring proper initialization, configuration, and cleanup within the application context.
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