Using custom @Enable annotations to toggle configuration

Allowing Spring Boot to automatically evaluate the classpath and detected configurations that are found there makes it very quick and easy to get a simple application going. However, there are times when we want to provide the configuration classes but require consumers of the starter library to explicitly enable such a configuration, rather than relying on Spring Boot to decide automatically if it should be included or not.

We will modify our previous recipe to make the starter be enabled via a meta-annotation rather than using the spring.factories route.

How to do it...

1. First, we will comment out the content of the spring.factories file located in db-count-starter/src/main/resources in the root of our project, as follows:

#org.springframework.boot.autoconfigure.EnableAutoConfiguration=
#com.example.bookpubstarter.dbcount.DbCountAutoConfiguration

2. Next, we will need to create the meta-annotation. We will create a new file named EnableDbCounting...