Demo Project to show new features in Spring-Boot 2.0.0 compared to 1.x

This project covers several changes in spring-boot 2.0.0 which are worth knowing. For a complete list of changes please take a look at the official release notes.

Currently this project contains changes from the latest released milestone 2.0.0M4.

Code structure
This repository contains three spring-boot-projects:

• spring-boot-2-demo which shows the new features, see below.
• spring-boot-1.5-demo which is meant to show the behaviour in 1.5 and compare to 2.0
• spring-boot-1.4-demo for comparing actuator behaviour between 1.4, 1.5 and 2.0

Features inherited from Spring Framework 5.0.0

@Nullable and @NonNullApi

Intention of the spring developers was to "leverage JSR 305 (...) meta-annotations to specify explicitly null-safety of Spring Framework parameters and return values", compare this commit message.
Another aim was to make the Spring-Framework null-safe for Kotlin. The annotations are also used for static code analysis, e.g. IntelliJ produces warnings when unsafe nullable usages are detected.

Besides these points described above, the @Nullable annotation can be used to declare that a object can be null which means it is not required. Places where it can be used:

• On field injection
• On controller injection
• In controllers requestmapping methods to define that e.g. a RequestParam is not required.

Example implementation see package newfeaturesin2.nullable in both projects.

Candidate Component Index

There is a new package spring-context-indexer which, if included as dependency, creates a index file META-INF/spring.components at build time. This file lists all candidate components (Spring Beans) as well as JPA candidates (Entities, Repositories).

Add following maven dependendy to active the new feature:

<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-context-indexer</artifactId>
</dependency>

For more details for this new feature see the commit message and the JIRA Discussion.

Simple hint for taking a look at the new mechanism via debugging in an IDE:

• CAUTION: This is just for taking a look at the new mechanism, should be reverted if going back to developing!
• Run a build, then copy META-INF/spring.components from the jar file to src/main/resources/META-INF/spring.components
• Breakpoints in
  • CandidateComponentsIndexLoader.loadIndex(..) where the index file is loaded
  • ClassPathScanningCandidateComponentProvider.findCandidateComponents(..) where the index is used ix exists, otherwise class path is scanned

To see that it works for JPA related candidates, checkout the branch jpa and run a build.

Changed or removed properties

• Several servlet related properties are now properly named, e.g.: server.context-path replaced with server.servlet.context-path
• Paging in spring-data-web can now easily be configured via properties (no example in project, but good to know)

Features from Spring Boot 2.0.0

Actuator

• Security management of the actuator endpoints has been refactored with 2.0.
  • Now endpoints can only be enabled or disabled.
  • Only /info and /status are enabled per default.
  • With adding spring-boot-starter-security and NO custom security configuration, all enabled actuator endpoints are available without authentification.
  • Having a custom security configuration, security of actuator endpoints must be configured in there. No defaults will be used then.
• All managing endpoints are moved to /application, for example the info endpoint is now available under /application/info. Default actuator endpoint can be changed with property management.context-path.
• Autoconfig endpoint /autoconfig contains autoconfigurations whithout conditions (@Conditional... annotations).
• Creating a custom actuator endpoint is much more easier now. Check out class PersonActuatorEndpoint in package newfeaturesin2.actuator.
  TODO: Implementation in spring-boot 1.x is still missing

@ConfigurationProperties needs @Validated

@Validated is now required, if there are any validation annotations in a @ConfigurationProperties class, which should be requested at startup.

Example implementation: see package newfeaturesin2.properties in both projects. In v1.x the application fails starting, if the property test.any is not set. In v2.x it only fails if the @Validated annotation is used.

New spring-boot-starter-json

Includes dependencies jackson-databind, jackson-datatype-jsr310 (necessary for convenient handling of java 8 data types) among others. The spring-boot-starter-json is in 2.0.0 included everywhere, where jackson-databind was used in 1.x. E.g. in the spring-boot-starter-web, so for my normal project setup there is no jackson dependency to be added explicitly anymore.