Append to XML document JAXB

Question

I have used JAXB to create an XML file like this:

-<persons>

    -<person>

        <active>Active</active>

        <amountOwed>500 Galleons</amountOwed>

        <email>harrypotter@hogwarts.edu</email>

        <firstName>harry</firstName>

        <lastName>potter</lastName>

        <memberNum>1234</memberNum>

        <school>Hogwarts</school>

        <state>some state</state>

        <yearJoined>1991</yearJoined>

    </person>

</persons>

I would like to use JAXB to append to this file like this:

-<persons>

    -<person>

        <active>Active</active>

        <amountOwed>500 Galleons</amountOwed>

        <email>harrypotter@hogwarts.edu</email>

        <firstName>harry</firstName>

        <lastName>potter</lastName>

        <memberNum>1234</memberNum>

        <school>Hogwarts</school>

        <state>some state</state>

        <yearJoined>1991</yearJoined>

    </person>

    <person>

        <active>Inactive</active>

        <amountOwed>123412362 Galleons</amountOwed>

        <email>ronweasley@hogwarts.edu</email>

        <firstName>ron</firstName>

        <lastName>weasley</lastName>

        <memberNum>2342</memberNum>

        <school>hogwarts</school>

        <state>some state</state>

        <yearJoined>1991</yearJoined>

    </person>

</persons>

I know XML is not a good fit for logging data, but I must use it for my project. How can I do this?

Answer 1

assuming the following class exists

@XmlRootElement
public class Persons{

List<Person> person;

...getters and setters
}

.

public class Person{
...fields, getters and setters...
}

first you unmarshal the origin xml

JAXBContext context = JAXBContext.newInstance(Persons.class);

        Unmarshaller unmarshaller = context.createUnmarshaller();

        File f = new File("the original xml");
        JAXBElement<Persons> personsElement = (JAXBElement<Persons>) unmarshaller.unmarshal(f);

and then you get the persons object

Persons persons = personsElement.getValue();

and then. put the object that you want to append

Person newPerson = new Person();

... put values into newPerson

persons.getPerson().add(newPerson);

last, you marshal it

Marshaller marshaller = context.createMarshaller();

        marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, Boolean.TRUE);
        marshaller.marshal(personsElement, the output Stream to your file);

You can also find a lot of example in oracle's tutorial

https://docs.oracle.com/javaee/5/tutorial/doc/bnbah.html