Spring Bean Scopes Explained With Code Samples

The Spring Framework allows defining scopes for a Spring Bean. Spring Bean scopes define the lifetime of a Spring bean. In this article, we will take a look at bean scopes.

What is Spring Bean Scope?

A Spring Bean scope specifies the lifetime of a Spring bean. So it specifies when the bean will be created and how long it will exist in the system.

What are the different bean scopes?

Spring supports the following bean scopes:

Singleton

This is the default bean scope. As per this scope, only one instance of a bean is created. Each time the bean is requested, the same instance is returned.

Prototype

As per this scope, a new instance of a bean is created each time the bean is requested.

Request

This bean scope is valid only for a web application. As per this bean scope, a new instance of the bean is created for each HTTP request. The bean stays alive until the HTTP request completes.  If you use this bean scope for a standalone application, your code will result in an error

Session

This bean scope is also valid only for a web application. As per this bean scope, a new instance of the bean is created for each HTTP session. The bean stays alive as long as the session is alive.  If you use this bean scope for a standalone application, your code will result in an error

Global Session

This bean scope is only valid for a portlet application. As per this bean scope, a new instance of the bean is created for each HTTP global session. It is similar to session scope used in a servlet based application.

How to define bean scopes?

Spring supports a @Scope annotation. You can use it to specify a Spring bean scope. As mentioned earlier, the default scope is singleton. However, if you want to specify the prototype scope for a bean, you can do it as follows:

@Service
@Scope("prototype")
public class MessageService {
  //code here
}

So this code defines a MessageService bean with prototype scope.

Further Learning

Spring MasterClass
Spring Tutorial For Beginners
Step by Step Spring MVC Tutorial
Spring Framework in Easy Steps

Conclusion

So, this article demonstrates the various Spring bean scopes like singleton, prototype, request, session and globalsession. It also demonstrates how you can define a bean scope.