I need to marshall and unmarshall a Java class to XML. The class in not owned by me, that I cannot add anotations so that I can use JAXB.
Is there a good way to convert the Java to XML with the given contraint?
Also, thought a tool may be helpful, but I would be more intersted it there is some Java API to do the same.
Note: I'm the EclipseLink JAXB (MOXy) lead and a member of the JAXB (JSR-222) expert group.
DOMAIN MODEL
I will use the following domain model for this answer. Note how there are no JAXB annotations on the model.
Customer
package forum11693552;
import java.util.*;
public class Customer {
private String firstName;
private String lastName;
private List<PhoneNumber> phoneNumbers = new ArrayList<PhoneNumber>();
public String getFirstName() {
return firstName;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
}
public String getLastName() {
return lastName;
}
public void setLastName(String lastName) {
this.lastName = lastName;
}
public List<PhoneNumber> getPhoneNumbers() {
return phoneNumbers;
}
public void setPhoneNumbers(List<PhoneNumber> phoneNumbers) {
this.phoneNumbers = phoneNumbers;
}
}
PhoneNumber
package forum11693552;
public class PhoneNumber {
private String type;
private String number;
public String getType() {
return type;
}
public void setType(String type) {
this.type = type;
}
public String getNumber() {
return number;
}
public void setNumber(String number) {
this.number = number;
}
}
OPTION #1 - Any JAXB (JSR-222) Implementation
JAXB is configurartion by exception, this means you only need to add annotations where you want the mapping behaviour to differ from the default. Below is a link to an example demonstrating how to use any JAXB impl without annotations:
Demo
package forum11693552;
import javax.xml.bind.*;
import javax.xml.namespace.QName;
public class Demo {
public static void main(String[] args) throws Exception {
JAXBContext jc = JAXBContext.newInstance(Customer.class);
Customer customer = new Customer();
customer.setFirstName("Jane");
customer.setLastName("Doe");
PhoneNumber workPhone = new PhoneNumber();
workPhone.setType("work");
workPhone.setNumber("555-1111");
customer.getPhoneNumbers().add(workPhone);
Marshaller marshaller = jc.createMarshaller();
marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
JAXBElement<Customer> rootElement = new JAXBElement<Customer>(new QName("customer"), Customer.class, customer);
marshaller.marshal(rootElement, System.out);
}
}
Output
<customer>
<firstName>Jane</firstName>
<lastName>Doe</lastName>
<phoneNumbers>
<number>555-1111</number>
<type>work</type>
</phoneNumbers>
</customer>
For More Information
OPTION #2 - EclipseLink JAXB (MOXy)'s External Mapping Document
If you do want to customize the mappings, then you may be interested in MOXy's external mapping document extension. A sample mapping document looks like the following:
oxm.xml
<?xml version="1.0"?>
<xml-bindings xmlns="http://www.eclipse.org/eclipselink/xsds/persistence/oxm"
package-name="forum11693552">
<java-types>
<java-type name="Customer">
<xml-root-element />
<java-attributes>
<xml-element java-attribute="firstName" name="first-name" />
<xml-element java-attribute="lastName" name="last-name" />
<xml-element java-attribute="phoneNumbers" name="phone-number" />
</java-attributes>
</java-type>
<java-type name="PhoneNumber">
<java-attributes>
<xml-attribute java-attribute="type" />
<xml-value java-attribute="number" />
</java-attributes>
</java-type>
</java-types>
</xml-bindings>
jaxb.properties
To enable MOXy as your JAXB provider you need to include a file called jaxb.properties in the same package as your domain model with the following entry (see: http://blog.bdoughan.com/2011/05/specifying-eclipselink-moxy-as-your.html):
javax.xml.bind.context.factory=org.eclipse.persistence.jaxb.JAXBContextFactory
Demo
When using EclipseLink MOXy as your JAXB provider (see), you can leverage the external mapping document when you bootstrap your JAXBContext
package forum11693552;
import java.util.*;
import javax.xml.bind.*;
import javax.xml.namespace.QName;
import org.eclipse.persistence.jaxb.JAXBContextFactory;
public class Demo {
public static void main(String[] args) throws Exception {
Map<String, Object> properties = new HashMap<String,Object>(1);
properties.put(JAXBContextFactory.ECLIPSELINK_OXM_XML_KEY, "forum11693552/oxm.xml");
JAXBContext jc = JAXBContext.newInstance(new Class[] {Customer.class}, properties);
Customer customer = new Customer();
customer.setFirstName("Jane");
customer.setLastName("Doe");
PhoneNumber workPhone = new PhoneNumber();
workPhone.setType("work");
workPhone.setNumber("555-1111");
customer.getPhoneNumbers().add(workPhone);
Marshaller marshaller = jc.createMarshaller();
marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
JAXBElement<Customer> rootElement = new JAXBElement<Customer>(new QName("customer"), Customer.class, customer);
marshaller.marshal(rootElement, System.out);
}
}
Output
<?xml version="1.0" encoding="UTF-8"?>
<customer>
<first-name>Jane</first-name>
<last-name>Doe</last-name>
<phone-number type="work">555-1111</phone-number>
</customer>
For More Information
Have you looked at XStream ? It will deserialise/deserialise a standard POJO without annotations or XSDs. You can provide customisations to affect how elements appear in the XML and pretty much works out-of-the-box.
You could write a custom XmlAdapter and annotate fields of the constrained type with a XmlJavaTypeAdapter annotation. The basics would be something like this:
public enum CannotBeAnnotated { value1, value2; }
@XmlRootElement(name="client")
public class ClientClass {
@XmlJavaTypeAdapter(Bridge.class)
public CannotBeAnnotated;
}
@XmlRootElement(name="representation")
public class XmlType {
@XmlValue
public String value;
}
public class Bridge extends XmlAdapter<XmlType, CannotBeAnnotated>{
public XmlType marshal(CannotBeAnnotated c) {
XmlType x=new XmlType();
x.value=c.name();
return x;
}
public CannotBeAnnotated unmarshall(XmlType x) {
return CannotBeAnnotated.valueOf(x.value);
}
}
Of course for enums this would not be useful as JAXB knows how to deal with them. I just picked an enum for simplicity so you can see the idea:
