Functional bean declaration DSL

In Spring, we register our beans either using XML or the  @Configuration and @Bean annotations. When Spring Boot is used from Kotlin, there is a new alternative to declare the beans using lambdas, which act as FactoryBean.

Registering beans in Java:

    GenericApplicationContext context = new   
     GenericApplicationContext();
    context.registerBean(Message.class);

With DSL style and reified type parameters, the Kotlin equivalent is as simple and beautiful as the following:

    beans {
      bean<Message>()
    }

Now that we understand the key constructs of Kotlin while building Spring Boot applications, let's move on to the example application.