#IT-HUSET Spring Boot 101 Welcome to IT-HUSET (http://www.it-huset.se) Spring Boot lab session 1!

This lab session will teach you to set up an end-to-end Spring Boot application that expose a PostgresQL database with a REST API.

The lab contains three parts, and different Git branches build upon the work in a previous part, so if you are stuck, you can always checkout the next branch. And look at the solution.

The parts are:

##Part 1, Basic code structure and dependencies. Git branch master. This is the starting point of the lab. By cloning this repository from Github you will checkout the master branch by default.

In this part of the lab we create the basic Spring Boot code structure. We also make sure we can package and run our app.

##Part 2, Adding web and REST capabilities with a starter POM. Git branch part2, git checkout -b origin/part2

In this part of the lab we add the required dependencies to build a REST API. We also experiment with the externalized configuration.

##Part 3, Connecting to a database and reading data. Git branch part3 git checkout -b origin/part3

In the last part of the lab, we add a unit test to our app, we also add required dependencies for Spring Data JPA. Finally we should be able to read data from a PostgresQL database and expose it with our previously build REST API.

##Solution Git branch solution git checkout -b origin/solution

To view the solution, checkout this branch. No assignments here!

#Part 1 - Lab assignment Welcome to the master branch! Your assignment is, if you choose to accept it, to output "Hello IT-HUSET" on the command line. You have a skeleton ready which does not do much at the moment besides that a parent POM and a Spring Boot Maven plugin has been added.

1. Look at the effective POM. By defining a parent POM, Spring Boot adds several properties important properties. For instance, java.version which defaults to 1.6, but we have overridden to be 1.8. The added Spring Boot plugin let us package the application as a standalone executable JAR (or war).
2. We now need the base Spring Boot dependency. Add:

<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter</artifactId>
</dependency>

1. From the previous step you can see that several dependencies was pulled in. The versions are defined in the parent POM. To update a Spring Boot application, you only need to update the version in the <parent></parent> element.
2. Now time for the application entrypoint. Open Application.javaand add three annotations to it:

@Configuration
@ComponentScan
@EnableAutoConfiguration

1. Time to bootstrap the application in the main-method by using the SpringApplication.run(x,y) method.
2. Either just to a System.out to output the required salution. For something more fancy, define a Spring bean with the message. Remember, that your Application.class now is also a Spring bean (it is annotated with @Configuration)!
3. On the command line, execute mvn package.
4. Run the executable JAR-file.
5. Notice the size of the JAR-file. You can also unpack it and study its contents. What do you think?

If you see your message, you are finished! Now go to part 2 of this lab by checking out the part2-branch.

#Part 2 - Lab assignment Available in the next Git branch.

#Part 3 - Lab assignment Available in the next Git branch.