JAXB annotation – mapping interface and @ xmlelementwrapper

I encountered a problem with the JAXB annotation of a field, which is a list and its generic type is an interface When I announce the following:

@XmlAnyElement
private List<Animal> animals;

Everything is normal But when I add a wrapper element, for example:

@XmlElementWrapper
@XmlAnyElement
private List<Animal> animals;

I found that Java objects were grouped correctly, but when I ungrouped documents created by grouping, my list was empty I have released the code below the code to demonstrate this problem

What did I do wrong, or was it a mistake? I've tried version 2.1 12 and 2.2-ea, the results are the same

I am mapping annotated interfaces through examples: https://jaxb.dev.java.net/guide/Mapping_interfaces.html

@XmlRootElement
class Zoo {

  @XmlElementWrapper
  @XmlAnyElement(lax = true)
  private List<Animal> animals;

  public static void main(String[] args) throws Exception {
    Zoo zoo = new Zoo();
    zoo.animals = new ArrayList<Animal>();
    zoo.animals.add(new Dog());
    zoo.animals.add(new Cat());

    JAXBContext jc = JAXBContext.newInstance(Zoo.class,Dog.class,Cat.class);
    Marshaller marshaller = jc.createMarshaller();

    ByteArrayOutputStream os = new ByteArrayOutputStream();
    marshaller.marshal(zoo,os);

    System.out.println(os.toString());

    Unmarshaller unmarshaller = jc.createUnmarshaller();
    Zoo unmarshalledZoo = (Zoo) unmarshaller.unmarshal(new ByteArrayInputStream(os.toByteArray()));

    if (unmarshalledZoo.animals == null) {
      System.out.println("animals was null");
    } else if (unmarshalledZoo.animals.size() == 2) {
      System.out.println("it worked");
    } else {
      System.out.println("Failed!");
    }
  }

  public interface Animal {}

  @XmlRootElement
  public static class Dog implements Animal {}

  @XmlRootElement
  public static class Cat implements Animal {}
}

Solution

This is in JAXB 2.1 Bug fixed in 13 Update the library or use JDK 1.7 or later, the problem will be solved