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Spring-on-Quarkus live coding
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spring-on-quarkus.md

spring-on-quarkus-demo project

This project uses Quarkus, the Supersonic Subatomic Java Framework. This project has been used to present Quarkus in several conferences and meetups. The slides are available here.

This project is the result of following the Quarkus Spring Web and Quarkus Spring Data JPA guides.

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

Spring on Quarkus Live coding

Project generation and run

Generate project by running the following command

mvn io.quarkus:quarkus-maven-plugin:1.5.2.Final:create \
    -DprojectGroupId=org.acme.spring.web \
    -DprojectArtifactId=spring-on-quarkus-demo \
    -DclassName="org.acme.spring.web.GreetingController" \
    -Dpath="/greeting" \
    -Dextensions="spring-web,resteasy-jsonb"

Navigate to the directory and launch the application

cd spring-on-quarkus-demo
mvn compile quarkus:dev
  1. Open browser to http://localhost:8080
  2. Open browser to http://localhost:8080/greeting

Add an url param

  1. Add a @RequestParam to hello method: 
    @GetMapping
public String hello(@RequestParam(defaultValue = "world")String name) {
    return "hello "+name;
}
  2. Open browser to http://localhost:8080/greeting?name=folks

Introduce a bean

  1. Create class Greeting in the org.acme.spring.web package with the following content: 
    package org.acme.spring.web;

public class Greeting {

    private String message;

    public Greeting(String message) {
        this.message = message;
    }

    public String getMessage() {
        return message;
    }
}
  2. Update the content of GreetingController to become: 
    package org.acme.spring.web;

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;


@RestController
@RequestMapping("/greeting")
public class GreetingController {

    @GetMapping
    public Greeting hello(@RequestParam(defaultValue = "world")String name) {
        return new Greeting("hello "+name);
    }
}
  3. Open browser to http://localhost:8080/greeting?name=folks

Introduce a Service

  1. Create class GreetingService in the org.acme.spring.web package with the following content: 
    package org.acme.spring.web;

import org.springframework.stereotype.Service;

public class GreetingService {

   public Greeting greet(String name){
       return new Greeting(name);
   }
}
  2. Update the content of GreetingController to become: 
    package org.acme.spring.web;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;


@RestController
@RequestMapping("/greeting")
public class GreetingController {

    @Autowired
    private GreetingService greetingService;

    @GetMapping
    public Greeting hello(@RequestParam(defaultValue = "world")String name) {
        return greetingService.greeting("hello "+name);
    }
}
  3. Open browser to http://localhost:8080/greeting?name=folks
  4. We get an error because we have not made the Service class a bean.
  5. Modify the service class to add an annotation to make it a bean, for instance @Service
  package org.acme.spring.web;
  
  import org.springframework.stereotype.Service;
  
  @Service
  public class GreetingService {
  
      public Greeting greeting(String name){
          return new Greeting(name);
      }
  }
  1. Refresh browser

Externalize values to configuration file

  1. In the GreetingService, add a message field.

  2. Use Constructor injection with @Value annotation which is what the Spring world use to use.

  3. Change the greet method to use the message field.

    package org.acme.spring.web;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Service;

@Service
public class GreetingService {

    private String message;

    public GreetingService(@Value("${greeting.message}")String message) {
        this.message = message;
    }

    public Greeting greet(String name){
        return new Greeting(message + " " + name);
    }
}

  4. Open browser to http://localhost:8080/greeting?name=folks

  5. We get an error because we have not added the property greeting.message to the configuration file

  6. Open the application.properties file and add:

    greeting.message=hola

  7. Refresh browser

Accessing data with Spring Data Jpa

Add needed quarkus extensions dependencies

  1. Open the pom.xml and add the quarkus-spring-data-jpa and quarkus-jdbc-postgresql 
        <dependency>
      <groupId>io.quarkus</groupId>
      <artifactId>quarkus-spring-data-jpa</artifactId>
    </dependency>
    <dependency>
      <groupId>io.quarkus</groupId>
      <artifactId>quarkus-jdbc-postgresql</artifactId>
    </dependency>

You can also add the extensions to your project by running the following command in your project base directory

./mvnw quarkus:add-extension -Dextensions="quarkus-spring-data-jpa,quarkus-jdbc-postgresql"

Create entity, repository and controller classes

  1. Create class Book in the org.acme.spring.web package with the following content:

    package org.acme.spring.web;

import javax.persistence.Entity;
import javax.persistence.Id;

@Entity
public class Book {

    @Id
    private Integer id;

    private String name;

    private Integer publicationYear;

    public Integer getId() {
        return id;
    }

    public String getName() {
        return name;
    }

    public Integer getPublicationYear() {
        return publicationYear;
    }
}

  2. Create a BookRepository interface and make it a Spring repository extending the Spring CrudRepository

    package org.acme.spring.web;

import org.springframework.data.repository.CrudRepository;

import java.util.List;

public interface BookRepostory extends CrudRepository<Book, Integer> {

    List<Book> findByPublicationYearBetween(Integer lower,Integer higher);
}

  3. Create the BookController class in order to expose the BookRepository via REST.

    package org.acme.spring.web;


import org.springframework.web.bind.annotation.*;

import java.util.List;

@RestController
@RequestMapping("/book")
public class BookController {

    private final BookRepository bookRepository;

    public BookController(BookRepository bookRepository) {
        this.bookRepository = bookRepository;
    }

    @GetMapping
    public Iterable<Book> findAll() {
        return bookRepository.findAll();
    }
}

  4. Open the application.properties file and add database access configuration

    quarkus.datasource.url=jdbc:postgresql:quarkus_test
quarkus.datasource.driver=org.postgresql.Driver
quarkus.datasource.username=quarkus_test
quarkus.datasource.password=quarkus_test
quarkus.datasource.max-size=8
quarkus.datasource.min-size=2

  5. Add database population script import.sql in resources folder with the following content

    INSERT INTO book(id, name, publicationYear) VALUES (1, 'Sapiens' , 2011);
INSERT INTO book(id, name, publicationYear) VALUES (2, 'Homo Deus' , 2015);
INSERT INTO book(id, name, publicationYear) VALUES (3, 'Enlightenment Now' , 2018);
INSERT INTO book(id, name, publicationYear) VALUES (4, 'Factfulness' , 2018);
INSERT INTO book(id, name, publicationYear) VALUES (5, 'Sleepwalkers' , 2012);
INSERT INTO book(id, name, publicationYear) VALUES (6, 'The Silk Roads' , 2015);

  6. Configure the loading of data adding the following properties in the application.properties file

    quarkus.hibernate-orm.database.generation=drop-and-create
quarkus.hibernate-orm.sql-load-script=import.sql

  7. At last, start a postgresql database by running the following command:

    docker run --ulimit memlock=-1:-1 -it --rm=true --memory-swappiness=0 --name quarkus_test -e POSTGRES_USER=quarkus_test -e POSTGRES_PASSWORD=quarkus_test -e POSTGRES_DB=quarkus_test -p 5432:5432 postgres:11.5

  8. Open browser to http://localhost:8080/book

Add a custom method in the repository

  1. Modify the BookRepository to add a custom method allowing retrieve books between publication dates.

    package org.acme.spring.web;

import org.springframework.data.repository.CrudRepository;

import java.util.List;

public interface BookRepository extends CrudRepository<Book, Integer> {

    List<Book> findByPublicationYearBetween(Integer lower,Integer higher);
}

  2. Add the following method to the BookController

    @GetMapping("year/{lower}/{higher}")
    public List<Book> findByPublicationYear(@PathVariable Integer lower, @PathVariable Integer higher){
        return bookRepository.findByPublicationYearBetween(lower,higher);
    }

  3. Open browser to http://localhost:8080/book/year/2012/2015

Add an Exception to customize responses

  1. Add a delete method in the BookController as follows:

        @DeleteMapping("/{id}")
    public void deleteBook(@PathVariable Integer id){
            bookRepository.deleteById(id);
    }

  2. Try to delete the book with id 10 by running the following command

     curl -X DELETE localhost:8080/book/10

    We get an 500 Internal Server Error because any book with id 10 exist.

  3. Create a MissingBookException class with following content:

    package org.acme.spring.web;

import org.springframework.http.HttpStatus;
import org.springframework.web.bind.annotation.ResponseStatus;

@ResponseStatus(HttpStatus.BAD_REQUEST)
public class MissingBookException extends RuntimeException {
}

  4. Use this custom Exception in the delete method in the BookController

    @DeleteMapping("/{id}")
    public void deleteBook(@PathVariable Integer id){
        try {
            bookRepository.deleteById(id);
        } catch (Exception e) {
            throw new MissingBookException();
        }
    }

  5. Retry to delete the book with id 10 by running the following command

    http DELETE localhost:8080/book/10

    We get a Bad Request response

    HTTP/1.1 400 Bad Request
Content-Length: 0
Content-Type: text/plain

Packaging and running the application

The application can be packaged using ./mvnw package. It produces the spring-on-quarkus-demo-1.0-SNAPSHOT-runner.jar file in the /target directory.

The application is now runnable using java -jar target/spring-on-quarkus-demo-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/spring-on-quarkus-demo-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/spring-on-quarkus-demo . Finally, run the container using docker run -i --net=host --rm -p 8080:8080 quarkus/spring-on-quarkus-demo

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

docker run -i --net=host --rm -p 8080:8080 quay.io/amunozhe/spring-boot-crud docker run -i --net=host --rm -p 8080:8080 quay.io/amunozhe/spring-quarkus-fruits-jvm docker run -i --net=host --rm -p 8080:8080 quay.io/amunozhe/spring-quarkus-fruits-native

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