Using @ConditionalOnMissingBean in Spring Boot

Introduction :

In Spring Boot, @ConditionalOnMissingBean is a powerful annotation used to conditionally create a bean only if another bean of the same type is not already present in the Spring context. This annotation provides flexibility in bean creation, allowing you to override default implementations or provide alternative implementations based on the absence of a bean. In this tutorial, we’ll explore how to use @ConditionalOnMissingBean with examples in a Spring Boot application.

Creating Beans with @ConditionalOnMissingBean

To create a bean conditionally using @ConditionalOnMissingBean, you annotate a method or configuration class with @Bean and @ConditionalOnMissingBean. If a bean of the specified type is not already present in the context, the annotated bean will be created and registered.

In this example, MyService bean will be created only if there is no other bean of the same type (MyService) already present in the Spring context.

Example: Using @ConditionalOnMissingBean

Let’s create a simple example to demonstrate the usage of @ConditionalOnMissingBean in a Spring Boot application.

In this example:

• MyService bean is annotated with @ConditionalOnMissingBean. It will only be created if there is no other bean of type MyService present in the context.
• AnotherService bean is created without any conditions.

Conclusion

In this tutorial, you learned how to use @ConditionalOnMissingBean in a Spring Boot application to conditionally create beans based on the absence of another bean of the same type. This annotation provides a flexible way to control bean creation and allows you to provide default implementations or alternative implementations based on the presence or absence of specific beans in the Spring context. By following the examples provided, you can easily integrate and use @ConditionalOnMissingBean in your own Spring Boot projects.