Getting Start with Spring Boot Configurations

Spring Boot allows development of Spring applications with minimum configuration. This is particular useful for developing microservices. This blog post will demonstrate a few things that may help in understanding how Spring Boot does its job of auto configuring a Spring application.


So what has been configured?

The main feature of Spring Boot is its ability to automatically configuration the Spring application based on its included jar files. So the first thing you may want to look at is what have been configured for you. This can be done by running the application with the debug flag either by adding “–debug” to the command line or JVM argument “-Ddebug“. You will then see the “Auto Configuration Report” displayed in your console like below:


Positive matches:

– @ConditionalOnClass classes found: org.springframework.context.annotation.EnableAspectJAutoProxy,org.aspectj.lang.annotation.Aspect,org.aspectj.lang.reflect.Advice (OnClassCondition)
– SpEL expression on org.springframework.boot.autoconfigure.aop.AopAutoConfiguration: ${} (OnExpressionCondition)

– SpEL expression on org.springframework.boot.autoconfigure.aop.AopAutoConfiguration$JdkDynamicAutoProxyConfiguration: !${spring.aop.proxyTargetClass:false} (OnExpressionCondition)

// rest omitted…

Negative matches:

– required @ConditionalOnClass classes not found: javax.jms.ConnectionFactory,org.apache.activemq.ActiveMQConnectionFactory (OnClassCondition)

// rest omitted…

The report should give you an indication of what have been configured for you. It depends mainly on what jar files you have included in your project dependencies.

Excluding an auto configuration

Spring Boot is designed so that you can gradually replaced the auto-configuration as needed. To exclude an auto configuration, use the exclude attribute of the @EnableAutoConfiguration annotation as below:

@EnableAutoConfiguration(exclude = ProcessEngineAutoConfiguration.class)
public class Application {

public static void main(String[] args) {, args);

I am using the Activiti Spring Boot module here. Note instead of relying on its auto configuration setup, I have included the activiti.xml configuration file using the @ImportResource annotation to manually configure the process engine used by Activiti.

Configuration properties

Application properties, e.g. JDBC connection string, are to be set in the file in the classpath. Profile specific properties should be included in a separate application-<profile>.properties file located at the same directory of the file.

A list of commonly used property keys can be found in the Reference Guide (here). For example, to change the embedded web server port to 8181, add the following line the the file




You may configure Spring Boot to use logging framework of your choice. But first, it may be useful to configure the logger properties and understand what has been configured for you. To do this, add the property of the format logging.level.<package name>=<level> to your file. For example, to display debug messages for Hibernate, add the following lilne:

That’s it. The above has helped me to get started with Spring Boot, to understand how auto configuration works. The Reference Guide provides a comprehensive documentation of the framework and various how-tos. There are also many tutorials and blog articles around for reference.


About Raymond Lee
Professional Java/EE Developer, software development technology enthusiast.

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