JAXB乱序解组引用@XmlID和@XmlIDREF

Question

I have the following xml:

Company.xml

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<company>
    <employeeList>
        <employee name="Jane Doe" id="A">
        </employee>
        <employee name="John Smith" id="B">
        </employee>
        <employee name="Anne Jones" id="C">
        </employee>
    </employeeList>
</company>

Department.xml

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<departmentList>
    <departmentList>
        <department name="Dev" id="1">
            <employee>A</employee>
            <employee>B</employee>
        </department>
        <department name="Sales" id="2">
            <employee>C</employee>
        </department>
    </departmentList>
</departmentList>

The class Department.java has an employee list

@XmlRootElement
@XmlAccessorType(XmlAccessType.FIELD)
public class Department {

    @XmlAttribute
    private String id;

    @XmlElement(name="employee")
    @XmlJavaTypeAdapter(EmpAdapter.class)
    public List<Employee> employeeList; 

    public Department(){
        employeeList = new ArrayList<Employee>();
    }

and the employee.java class has an id attribute with the @XmlId tag.

@XmlRootElement
@XmlAccessorType(XmlAccessType.FIELD)
public class Employee {

        @XmlAttribute
        @XmlID
        private String id;

I know how to get the employee objects to be pointed at from the department object using an adapter. However that is if the Company.xml file is unmarshalled first because it has the employee details in it.

So what I want is to be able to unmarshall the Department.xml first and have it create some sort of placeholder so that once the Company.xml has been unmarshalled the employeeList in the department object is filled in.

EDIT

POSSIBLE SOLUTION : As suggested by @laune I can use the adapter to create Employee objects as a placeholder, and then once the employee list is unmarshalled fill in these details in the employee objects under the department class

WHAT I NEED: But this way I have to always handle each of the cases individually through code and new methods. Main problem is I cannot predict the order in which the unmarshalling will happen. Is there a way to have JAXB unmarshall without worrying about dependencies and ordering of creating objects? Maybe using schemas?

Answer 1

You can modify the EmpAdapter to return a placeholder Employee object created from an (additional) constructor

public Employee( String id ){
    this.id = id;
}

Also, the EmpAdapter should maintain a Map<String,Employee> mapping ids to employees.

After you have unmarshalled the employees into a flat list, iterate the list and fill the fields of the placeholder (located via the map) from the list element.

Things would be much easier if employee data contains the deparment id.