What is Auto-Configuration? How to Enable or Disable Certain Configuration?

Spring boot auto configuration scans the classpath, finds the libraries in the classpath and then attempt to guess the best configuration for them, and finally configure all such beans.

Auto-configuration tries to be as intelligent as possible and will back-away as we define more of our own custom configuration. It is always applied after user-defined beans have been registered.

Auto-configuration works with help of @Conditional annotations such as @ConditionalOnBean and @ConditionalOnClass.

For example, look at AopAutoConfiguration class.

If class path scanning finds EnableAspectJAutoProxy, Aspect, Advice and AnnotatedElement classes and spring.aop.auto=false is not present in properties file then Spring boot will configure the Spring AOP module for us.

@Configuration @ConditionalOnClass({ EnableAspectJAutoProxy.class, Aspect.class, Advice.class, AnnotatedElement.class }) @ConditionalOnProperty(prefix = "spring.aop", name = "auto", havingValue = "true", matchIfMissing = true) public class AopAutoConfiguration {//code}

Yaniv Levy

Yaniv Levy, Entrepreneur, visioner & technology passionate with over 20 years on vast experience as a Senior Software Engineer and a Software Architect.

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