Spring Bean Scopes

• In Spring Framework, bean scopes define the lifecycle and visibility of beans in the Spring IoC container.
• @Scope defines a bean's lifecycle and visibility of the bean.

Common @Scope Values

1. singleton( by default)

   • Only one instance of the bean per Spring container.
   • Same object is shared everywhere.
   • This is the default scope if no other scope is specified.
   • Lifecycle: The bean is created when the application context is initialized and destroyed when the context is destroyed.
     

2. prototype

   • A new instance is created every time the bean is requested.9
   • Lifecycle: Created every time requested, not managed by Spring after that.
     

3. request (Web-aware only)

   • One bean instance per HTTP request.
   • Used in web applications (Spring MVC).
   • Lifecycle: Created for each HTTP request, destroyed at request end
     

4. session(Web-aware only)

   • One bean instance per HTTP session.
   • lifecycle: Created for each HTTP session, destroyed when session ends
     

5. application (Web-aware only)

   • One bean instance per ServletContext (entire web app).
   • Similar to singleton but specific to web context.
   • Lifecycle: Created when ServletContext is initialized, destroyed at shutdown.
     

6. websocket(Web-aware only, since Spring 4.2)

   • One bean instance per WebSocket session.
   • Lifecycle: Created when WebSocket session is established, destroyed at session end

Example:

XMLAnnotation

<bean id="myBean" class="com.example.MyBean" scope="prototype"/>

@Component            // stereotype (registers the bean)
@Scope("prototype")   // modifies its lifecycle(Define the scope as prototype)
public class MyBean { 
   //Bean defination
}

Points to remember

• @Scope is applied at the class level.
• Affects the Spring-managed bean, not the class itself.
• Each bean (even from the same class) can have a different scope.
• Does not apply globally to the class — only to the specific bean definition.

Example Code

@Configuration
public class AppConfig {

   @Bean
   @Scope("singleton")  // First bean with singleton scope
   public MyBean singletonBean() {
      // This scope applies only to the Spring-managed bean of singletonBean
      return new MyBean();
   }

   @Bean
   @Scope("prototype")  // Second bean with prototype scope
   public MyBean prototypeBean() {
      // This scope applies only to the Spring-managed bean of prototypeBean
      return new MyBean();
   }
}

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Github Code : Bean Scope : Spring