Welcome to the Kotlin Bootique Workshop. The Kotlin Bootique application provides a very minimalistic implementation of a RESTful API for building a Webshop. The application consists of the following endpoints:
| Uri | HttpMethod | Description |
|---|---|---|
| /products | GET | retrieve product and price information |
| /baskets/{id} | GET | retrieve a shopping basket |
| /baskets/{id}/items | POST | adding an item to a basket |
Throughout this workshop you are going to convert this Spring Boot based application written in Java to the Kotlin equivalent. You will be guided through some of the challenges you as a developer will be facing while migrating existing applications to Kotlin.
If you are able to successfully complete this workshop, you should have enough knowledge to start using Kotlin in any of your (existing) Java projects.
This tutorial assumes that you at least have some basic knowledge about Java 8, Maven, Git and Spring Boot.
Download and install git from https://git-scm.com/downloads
Make sure you have at least JDK 11 installed. You can check which version is installed by executing in your terminal:
java -version
Should output something similar like:
java -version
openjdk version "11.0.5" 2019-10-15
OpenJDK Runtime Environment AdoptOpenJDK (build 11.0.5+10)
OpenJDK 64-Bit Server VM AdoptOpenJDK (build 11.0.5+10, mixed mode)Java can be downloaded from the AdaptOpenJDK website: https://adoptopenjdk.net/. Or, if you really need to, from the Oracle website: http://www.oracle.com/technetwork/java/javase/downloads/index.html.
In this tutorial we assume that you will be using IntelliJ because of it`s excellent Kotlin support! That makes sense considering Kotlin was invented and created by JetBrains, the creator of IntelliJ.
IntelliJ Ultimate Edition is preferred but IntelliJ Community will also work. IntelliJ can be downloaded from: https://www.jetbrains.com/idea/download/.
The Kotlin Bootique exercises can be found in a separate git repository. Please clone the source to your local machine from github:
git clone https://github.com/sourcelabs-nl/kotlin-bootique-exercises
Keep this documentation open in your browser while completing the exercises.
Open the project in IntelliJ ( File > Open... ) or navigate with your favorite terminal application to the location where you just cloned the project.
You can build the project using maven by executing the following command:
./mvnw clean install
mvnw is no typo, this makes sure you are using the maven wrapper file. If you experience issues with you existing maven settings file you can use the provided settings.xml inside the project. Or temporarily renamed your settings.xml to settings.tmp.
./mvnw -s settings.xml clean install
You can launch the BootiqueApplication by running the project using the spring-boot maven plugin. Execute the following maven command:
./mvnw spring-boot:run
The Kotlin Bootique application exposes a Swagger endpoint that allows you to explore the API: http://localhost:8080/swagger-ui.html
Alternatively you can also execute request inside IntelliJ against the API using the provided HTTP Request files in the /http folder or by using curl on the command-line.
You can list all the products using your browser, Swagger or curl
curl -X GET http://localhost:8080/products
You can view the content of your basket using your browser, Swagger or curl
curl -X GET http://localhost:8080/baskets/1
You can add items to the basket using Swagger or curl
curl -H "Content-Type: application/json" -X POST -d '{"productId":"1","quantity":2}' http://localhost:8080/baskets/1/items
curl -H "Content-Type: application/json" -X POST -d '{"productId":"2","quantity":4}' http://localhost:8080/baskets/1/items
This workshop consist of several exercises that will guide you through the process of converting the Java code to Kotlin. Each of the exercises are in the kotlin-bootique-exercises project on an separate git branch.
By checking out each exercise branch, you will start of with a working implementation of the previous exercise.
You can start your journey now by switching to the exercise-1 branch, either by using IntelliJ or, by issue the following command in your terminal:
git checkout exercise-1
Please keep this documentation open in your browser while completing the exercises. The lines marked with: Exercise are the task that need to be performed!
The documentation for the first exercise can be found here: exercise-1.md
Enjoy the ride!