Some explanations about the inner workings of Spring Boot

1. SPRING BOOT
UNDER THE
HOOD
@NICOLAS_FRANKEL

2. ME, MYSELF AND I
@nicolas_frankel #springboot
2
 Developer/Software -
/Solution Architect
• Java
• As consultant

3. HYBRIS, AN SAP COMPANY
3
@nicolas_frankel #springboot

4. @nicolas_frankel #springboot
4

5. @nicolas_frankel #springboot
5

6. SPRING BOOT ACTUATOR
<dependency>
<groupId>
org.springframework.boot
</groupId>
<artifactId>
spring-boot-starter-actuator
</artifactId>
</dependency>
@nicolas_frankel #springboot
6

7. /HEALTH
{
"status" : "UP",
"diskSpace" : {
"status" : "UP",
"total" : 499055067136,
"free" : 254812135424,
"threshold" : 10485760
},
"db" : {
"status" : "UP",
"database" : "HSQL Database Engine",
"hello" : 1
}
}
@nicolas_frankel #springboot
7

8. SPRING BOOT
Works well until:
• It doesn’t anymore
• Or you want to change the
default behavior
@nicolas_frankel #springboot
8

9. CONFIGURATION – POM.XML
<dependency>
<groupId>
org.springframework.boot
</groupId>
<artifactId>
spring-boot-starter-data-jpa
</artifactId>
</dependency>
<dependency>
<groupId>org.hsqldb</groupId>
<artifactId>hsqldb</artifactId>
<scope>runtime</scope>
</dependency>
@nicolas_frankel #springboot
9

10. LET’S CHECK HOW IT WORKS
@nicolas_frankel #springboot
10

11. STARTERS DEPENDENCIES
@nicolas_frankel #springboot
11

12. SPRING-BOOT-AUTOCONFIGURE.JAR
@nicolas_frankel #springboot
12

13. SPRING.FACTORIES
@nicolas_frankel #springboot
13

14. @JPAREPOSITORIESAUTOCONFIGURATION
@Configuration
@ConditionalOnBean(DataSource.class)
@ConditionalOnClass(JpaRepository.class)
@ConditionalOnMissingBean({
JpaRepositoryFactoryBean.class,
JpaRepositoryConfigExtension.class })
@ConditionalOnProperty(
prefix = "spring.data.jpa.repositories",
name = "enabled", havingValue = "true",
matchIfMissing = true)
@Import(JpaRepositoriesAutoConfigureRegistrar.class)
@AutoConfigureAfter(
HibernateJpaAutoConfiguration.class)
public class JpaRepositoriesAutoConfiguration {
}
@nicolas_frankel #springboot
14

15. @CONDITIONAL
@ConditionalOnBean
@ConditionalOnClass
@ConditionalOnMissingBean
@ConditionalOnProperty
etc.
@nicolas_frankel #springboot
15

16. REMEMBER @PROFILE?
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.TYPE)
public @interface Profile {
String[] value();
}
@nicolas_frankel #springboot
16

17. THIS IS THE NEW @PROFILE
@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.TYPE,
ElementType.METHOD})
@Documented
@Conditional(ProfileCondition.class)
public @interface Profile {
String[] value();
}
@nicolas_frankel #springboot
17

18. @CONDITIONAL & CONDITION
@nicolas_frankel #springboot
18

19. @CONDITIONAL & CONDITION
Enables calling of a @Bean-
annotated method
• In the context of a
@Configuration class
@nicolas_frankel #springboot
19

20. ENOUGH TALK…
@nicolas_frankel #springboot
20

21. OUT-OF-THE-BOX CONDITIONS
Condition Description
OnBeanCondition Checks if a bean is in the Spring factory
OnClassCondition Checks if a class is on the classpath
OnExpressionCondition Evalutates a SPeL expression
OnJavaCondition Checks the version of Java
OnJndiCondition Checks if a JNDI branch exists
OnPropertyCondition Checks if a property exists
OnResourceCondition Checks if a resource exists
OnWebApplicationCondition Checks if a WebApplicationContext exists
@nicolas_frankel #springboot
21

22. COMPOSITE CONDITIONS
Condition Description
AllNestedConditions AND condition
AnyNestedConditions OR condition
NoneNestedCondition NOT condition
@nicolas_frankel #springboot
22

23. OUR OWN STARTER
@nicolas_frankel #springboot
23

24. Q&A
@nicolas_frankel #springboot
24
http://blog.frankel.ch/
@nicolas_frankel
http://frankel.in/
https://git.io/v2f3O