使用JAXB解组为POJO后返回为null的列表

@XmlRootElement
public class MyClass {
    @XmlElementWrapper(name = "myList")
    @XmlElement(name = "item")
    private List<String> myList = new ArrayList<>();

    // 其他属性和方法
}

public class ListAdapter extends XmlAdapter<MyListWrapper, List<String>> {

    @Override
    public List<String> unmarshal(MyListWrapper wrapper) {
        if (wrapper == null || wrapper.getItems() == null) {
            return new ArrayList<>(); // 返回空列表或默认值
        } else {
            return wrapper.getItems();
        }
    }

    @Override
    public MyListWrapper marshal(List<String> list) {
        MyListWrapper wrapper = new MyListWrapper();
        wrapper.setItems(list);
        return wrapper;
    }
}

public class MyListWrapper {
    private List<String> items;

    // getter和setter方法

    // 其他属性和方法
}

Unmarshaller unmarshaller = context.createUnmarshaller();
unmarshaller.setListener(new Unmarshaller.Listener() {
    @Override
    public void beforeUnmarshal(Object target, Object parent) {
        if (target instanceof MyClass && parent instanceof JAXBElement) {
            JAXBElement element = (JAXBElement) parent;
            if (element.isNil()) {
                MyClass myClass = (MyClass) target;
                myClass.setMyList(new ArrayList<>()); // 设置为空列表
            }
        }
    }
});