What is the scope of spring bean?
We have already seen what a spring bean is and the lifecycle of a spring bean. Not all beans are created equal, and understanding their scope is crucial for designing and implementing robust and efficient systems. In this blog post, we’ll see the scope of spring bean, exploring what they are, how they work, and when to use them.
In Spring, a bean’s scope defines the lifecycle and visibility of an instance managed by the Spring IoC (Inversion of Control) container. The scope determines how and when bean instances are created, stored, and destroyed, as well as the visibility of these instances within the application context. Spring provides several predefined bean scopes, each catering to different use cases and scenarios.
Common Bean Scopes in Spring:
Let’s explore some of the most commonly used bean scopes in Spring:
1. Singleton:
- The singleton scope is the default scope in Spring and ensures that only one instance of a bean is created per Spring IoC container.
- This means that all requests for the bean within the container result in the same shared instance.
- Singleton beans are suitable for stateless components and resources that can be safely shared across multiple clients.
2. Prototype:
- The prototype scope instructs the Spring IoC container to create a new instance of the bean whenever requested.
- Unlike singleton beans, prototype beans are not shared across the application context, and each client receives a separate instance.
- Prototype beans are ideal for stateful components and resources that require isolation and independence.
3. Request and Session (Web-specific scopes):
In web applications, Spring provides additional scopes tailored to the HTTP request and session lifecycle.
- Request scope ensures that a new instance of the bean is created for each HTTP request, while session scope ensures that a single instance is maintained for the duration of the user session.
- These scopes are typically used for web controllers, handlers, and session-specific data.
4. Custom Bean Scopes:
- In addition to the predefined scopes, Spring allows developers to define custom bean scopes tailored to specific application requirements.
- Custom scopes can be implemented by extending the AbstractBeanFactoryScope class or implementing the Scope interface, providing fine-grained control over bean instantiation and lifecycle management.
Choosing the Right Scope:
Selecting the appropriate bean scope depends on various factors, including the nature of the bean, its lifecycle requirements, and the application architecture. Here are some guidelines to consider when choosing a bean scope:
- Singleton scope is suitable for stateless components and resources that can be safely shared across the application.
- The prototype scope is ideal for stateful components and resources that require isolation and independence.
- Request and session scopes are specific to web applications and should be used for web controllers, handlers, and session-specific data.
- Custom scopes can be used to address unique application requirements and provide specialized lifecycle management.
In conclusion, the Spring bean scope plays a critical role in defining the lifecycle and visibility of bean instances within the Spring IoC container. By understanding the characteristics and use cases of different bean scopes, developers can design and implement more efficient, scalable, and maintainable applications whether leveraging the default singleton scope or customizing scopes to meet specific requirements, mastering bean scope management is essential for harnessing the full power of the Spring Framework.
