Spring Webflux JAXB

In this technical post we will take a look at how to produce XML using JAXB Jakarta EE implementation. Java Architecture for XML Binding (JAXB) provides an API and tools that automate the mapping between XML documents and Java objects. NOTE: If you need to know what tools you need to have installed in your computer in order to create a Spring Boot basic project, please refer my previous post: Spring Boot. Let’s start creating a new Spring Webflux with Lombok as dependency:

 spring init --dependencies=webflux,lombok --build=gradle --language=java spring-webflux-jaxb

Here is the complete build.gradle file generated:

plugins {
	id 'org.springframework.boot' version '2.2.1.RELEASE'
	id 'io.spring.dependency-management' version '1.0.8.RELEASE'
	id 'java'
}

group = 'com.jos.dem.spring.webflux.jaxb'
version = '0.0.1-SNAPSHOT'
sourceCompatibility = '11'

configurations {
	compileOnly {
		extendsFrom annotationProcessor
	}
}

repositories {
	mavenCentral()
}

dependencies {
	implementation 'org.springframework.boot:spring-boot-starter-webflux'
	compileOnly 'org.projectlombok:lombok'
	annotationProcessor 'org.projectlombok:lombok'
	testImplementation('org.springframework.boot:spring-boot-starter-test') {
		exclude group: 'org.junit.vintage', module: 'junit-vintage-engine'
	}
	testImplementation 'io.projectreactor:reactor-test'
}

test {
	useJUnitPlatform()
}

Then add JAXB api and runtime dependencies:

implementation "javax.xml.bind:jaxb-api"
implementation "org.glassfish.jaxb:jaxb-runtime"

Let’s start adding a controller to retreive an XML

package com.jos.dem.spring.webflux.jaxb.controller;

import static org.springframework.http.MediaType.APPLICATION_XML_VALUE;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
import reactor.core.publisher.Mono;

import com.jos.dem.spring.webflux.jaxb.model.Person;
import com.jos.dem.spring.webflux.jaxb.repository.PersonRepository;

@RestController
public class PersonController {

  @Autowired
  private PersonRepository personRepository;

  private Logger log = LoggerFactory.getLogger(this.getClass());

  @GetMapping(value = "/", produces = APPLICATION_XML_VALUE)
  public Mono<Person> index() {
    log.info("Getting Person");
    return personRepository.findOne("josdem");
  }

}

That’s it, adding APPLICATION_XML_VALUE as MediaType to the @GetMapping annotation will do the magic :). Here is our Person model:

package com.jos.dem.spring.webflux.jaxb.model;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.Getter;
import lombok.NoArgsConstructor;

import javax.xml.bind.annotation.XmlRootElement;
import javax.xml.bind.annotation.XmlAttribute;
import javax.xml.bind.annotation.XmlElement;

@Getter
@AllArgsConstructor
@NoArgsConstructor
@XmlRootElement
public class Person {
  @XmlAttribute
  private String nickname;
  @XmlAttribute
  private String firstName;
  @XmlAttribute
  private String lastName;
  @XmlAttribute
  private String address;
  @XmlElement
  private Device device;
}

Where:

• @XmlRootElement annotation associate a root element with our Person class.
• @XmlAttribute Will map to a XML field attribute.
• @XmlElement Will map to a XML element.

Here is our Device model:

package com.jos.dem.spring.webflux.jaxb.model;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.Getter;
import lombok.NoArgsConstructor;

import javax.xml.bind.annotation.XmlRootElement;
import javax.xml.bind.annotation.XmlAttribute;

@Getter
@AllArgsConstructor
@NoArgsConstructor
@XmlRootElement
public class Device {
  @XmlAttribute
  private String name;
  @XmlAttribute
  private String os;
  @XmlAttribute
  private String model;
}

Finally, let’s test our controller with WebTestClient

package com.jos.dem.spring.webflux.jaxb;

import com.jos.dem.spring.webflux.jaxb.model.Person;
import org.junit.jupiter.api.Test;
import org.junit.jupiter.api.DisplayName;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.web.reactive.server.WebTestClient;

import static org.hamcrest.Matchers.equalTo;
import static org.springframework.http.MediaType.APPLICATION_XML_VALUE;

@SpringBootTest(classes = DemoApplication.class,
				webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
class DemoApplicationTests {

	@Autowired
	private WebTestClient webClient;

	@Test
  @DisplayName("Should Get Person")
  void shouldGetPerson() {
    webClient.get().uri("/")
            .exchange()
            .expectStatus().isOk()
            .expectHeader().contentType(APPLICATION_XML_VALUE)
            .expectBody(Person.class)
            .value(person -> person.getFirstName(), equalTo("Jose"))
            .value(person -> person.getLastName(), equalTo("Morales"))
            .value(person -> person.getAddress(), equalTo("30 Frank Lloyd, Ann Arbor MI 48105"))
            .value(person -> person.getDevice().getName(), equalTo("Pixel 3"))
            .value(person -> person.getDevice().getOs(), equalTo("Android"))
            .value(person -> person.getDevice().getModel(), equalTo("9 Pie"));
	}

}

If you want to test this project from command line

curl -v http://localhost:8080 \
-H 'Content-Type: application/xml'

You should see an output similar to this:

* Connected to localhost (127.0.0.1) port 8080 (#0)
> GET / HTTP/1.1
> Host: localhost:8080
> User-Agent: curl/7.58.0
> Accept: */*
> Content-Type: application/xml
>
< HTTP/1.1 200 OK
< Content-Type: application/xml
< Content-Length: 222
<
* Connection #0 to host localhost left intact
<?xml version="1.0" encoding="UTF-8" standalone="yes"?><person nickname="josdem" firstName="Jose" lastName="Morales" address="30 Frank Lloyd, Ann Arbor MI 48105"><device name="Pixel 3" os="Android" model="9 Pie"/></person>

To browse the project go here, to download the project:

git clone git@github.com:josdem/spring-webflux-jaxb.git

To run the project:

gradle bootRun

To test the project:

gradle test

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