Quarkus getting-started live coding

getting-started.md

getting-started project

This project uses Quarkus, the Supersonic Subatomic Java Framework. This project has been used to present Quarkus in Codemotion Madrid 2019. The slides are available [here](Codemotion 2019 Descubriendo Quarkus%2C java sub-atómico en acción.pdf).

This project is the result of following the Quarkus getting started guide.

If you want to learn more about Quarkus, please visit its website: https://quarkus.io/ .

Quarkus Hello World Live coding

Project generation and run

1. Generate project

mvn io.quarkus:quarkus-maven-plugin:1.5.2.Final:create \
    -DprojectGroupId=org.acme \
    -DprojectArtifactId=getting-started \
    -DclassName="org.acme.getting.started.GreetingResource" \
    -Dpath="/hello"

1. Navigate to the directory and launch the application

   cd getting-started
   mvn compile quarkus:dev

2. Open browser to http://localhost:8080
3. Open browser to http://localhost:8080/hello
4. Change the greeting message in the HelloResource, refresh browser

Add method

1. Add method:

   @GET
   @Produces(MediaType.TEXT_PLAIN)
   @Path("/city")
   public String city() {
       return "Madrid";
   }
   

2. Open browser to http://localhost:8080/hello/city

Configuration

1. In the resource, add

   @ConfigProperty(name = "greeting") String greeting;
   

2. Change the hello method to return the greeting message:

   @GET
   @Produces(MediaType.TEXT_PLAIN)
   public String hello() {
       return greeting;
   }
   

3. Open browser to http://localhost:8080/hello
4. We get an error because we have not added the property greeting to the configuration file
5. Open the application.properties file and add:

   greeting=Hola
   

6. Refresh browser
7. In the resource class, add an Optional<String>:

   @ConfigProperty(name = "city") Optional<String> city;
   

8. Replace the city method with:

   @GET
   @Produces(MediaType.TEXT_PLAIN)
   @Path("/city")
   public String city() {
       return city.orElse("Barcelona");
   }
   

9. Open browser to http://localhost:8080/hello/city

Introduce a bean

1. Create class MyBean in the org.acme.quickstart package with the following content:

   @ApplicationScoped
   public class MyBean {
   
       @ConfigProperty(name = "greeting") String greeting;
   
       public String greeting() {
           return greeting;
       }
   }
   

2. Update the content of HelloResource to become:

   @Inject 
   MyBean bean;
   
   @GET
   @Produces(MediaType.TEXT_PLAIN)
   public String hello() {
       return bean.greeting();
   }
   

3. Open browser to http://localhost:8080/hello

Packaging and running the application

The application can be packaged using ./mvnw package. It produces the getting-started-1.0-SNAPSHOT-runner.jar file in the /target directory.

The application is now runnable using java -jar target/getting-started-1.0-SNAPSHOT-runner.jar.

Creating a native executable

You can create a native executable using: ./mvnw package -Pnative. You can then execute your native executable with: ./target/getting-started-1.0-SNAPSHOT-runner

Or, if you don't have GraalVM installed, you can run the native executable build in a container using: ./mvnw package -Pnative -Dquarkus.native.container-build=true. Then, build the docker image with docker build -f src/main/docker/Dockerfile.native -t quarkus/getting-started . Finally, run the container using docker run -i --rm -p 8080:8080 quarkus/getting-started

If you want to learn more about building native executables, please consult https://quarkus.io/guides/building-native-image.