Play with Spring Boot

Spring Boot is something really exciting (see 1.3.0 release note to convince yourself), every Java geek should have hear about it !

Let's play with it, with easy understandable examples :)

For spelling, sorry, I'm French...

Wiki

First, we need an IDE (ok it's not a requirement but we don't want to have an headache...) and setup few little things: here is the wiki.

Projects

hello-world-jersey-minimum and hello-world-sb-jersey-minimum

MVP MVP !
These 2 projects have the minimum to expose a REST service with Jersey and Spring.

Difference between them ? Spring Boot of course !

hello-world-sb-jersey-minimum is simply the Spring Boot version of hello-world-jersey-minimum.

For both, I followed Servlet 3.0 spec, thanks to this Xebia tuto.

hello-world-jersey-logs

This project demonstrate how it is easy to setup logs with Spring Boot.

• I add a embedded application.properties to be able to default some Spring Boot settings, here only spring.application.name.
• Have a look at logback-spring.xml
  • By default Spring Boot use a log rotation based on file size, I prefer time based rotation so I override the FILE appender and keep other default settings.
  • Note that I use <springProperty name="spring.application.name" source="spring.application.name"/> to refer to the property I have set in the embedded application.properties and use it as the base name of log files.

hello-world-jersey-dev-tools

See how Spring Boot detect changes on the classpath and restart automatically app to reflect changes (more infos here: https://spring.io/blog/2015/06/17/devtools-in-spring-boot-1-3).

• Note that it doesn't work when app is running with maven command line, you have to use Run As > Java Application or Run As > Spring Boot App

hello-world-sb-jersey-tests

You want to make some integration tests, see how it is easy to start your app and call it from your JUnit test

hello-world-sb-jersey-command-line-args

Example of an app that check args at boot and exit if it isn't compliant.

• Focus on ArgsValidator class to see how it works (as always, it is easy understandable).
• Also notice <configuration><executable>true</executable></configuration> in pom.xml, this simple param convert the output jar file to a fully executable one:
• Without this instruction, you have to start your jar with java -jar myapp.jar
• With this instruction, you have to start your jar like any executable: ./myapp.jar

hello-world-sb-jersey-actuator

The last but not the least : the Actuator.
With juste few lines of conf, it enable a lof of production features to control and check your app.