JAXB XML; How to fetch an attribute of an element without needing to create a pojo of the element?-CodePudding

Let's say I only need a few attributes of 'child'

<parent>
   <child name="Child" age="1" />
</parent>

I dont want to have to create a 'child' class. I just want to wrap it and fetch the attribute. Is this possible? Is there any wrapper annotation I can use?

CodePudding user response：

Well, you can do it but if you don't take the traditional method then it will become really tricky. Here is the code which you can try:

XML:

<parent>
    <child name="Child" age="1" />
</parent>

Root:

@XmlRootElement(name = "parent")
@XmlAccessorType(XmlAccessType.PROPERTY)
public class Root {
    @XmlJavaTypeAdapter(Adapter.class)
    private String child;
}

Child:

@Data
@XmlRootElement
@XmlAccessorType(XmlAccessType.FIELD)
public class Child {
    @XmlAttribute
    private String name;

    @XmlAttribute
    private String age;
}

Adapter:

public class Adapter extends XmlAdapter<Child, String> {

    public String unmarshal(Child pC) throws Exception {
        System.out.println(pC.toString());
        return null;
    }

    public Child marshal(String pC) throws Exception {
        return null;
    }
}

Main:

public class Main {
    public static void main(String[] args) throws JAXBException, XMLStreamException {
        final InputStream inputStream = Main.class.getClassLoader().getResourceAsStream("sample.xml");
        final XMLStreamReader xmlStreamReader = XMLInputFactory.newInstance().createXMLStreamReader(inputStream);
        final Unmarshaller unmarshaller = JAXBContext.newInstance(Root.class).createUnmarshaller();
        final Root root = unmarshaller.unmarshal(xmlStreamReader, Root.class).getValue();
        System.out.println(root.toString());
    }
}

Output:

Child(name=Child, age=1)

Updated to store everything without child classes

XML:

<parent>
    <child name="Child" age="1" />
</parent>

Root:

@Data
@XmlRootElement(name = "parent")
@XmlAccessorType(XmlAccessType.FIELD)
public class Root {
    @XmlAnyElement
    private List<Object> any;
}

Main:

public class Main {
    public static void main(String[] args) throws JAXBException, XMLStreamException {
        final InputStream inputStream = Main.class.getClassLoader().getResourceAsStream("sample.xml");
        final XMLStreamReader xmlStreamReader = XMLInputFactory.newInstance().createXMLStreamReader(inputStream);
        final Unmarshaller unmarshaller = JAXBContext.newInstance(Root.class).createUnmarshaller();
        final Root root = unmarshaller.unmarshal(xmlStreamReader, Root.class).getValue();
        System.out.println(root.toString());

        Marshaller marshaller = JAXBContext.newInstance(Root.class).createMarshaller();
        marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
        marshaller.setProperty(Marshaller.JAXB_ENCODING, "US-ASCII");
        //marshaller.setProperty("com.sun.xml.internal.bind.xmlHeaders", new XmlCharacterHandler());
        marshaller.marshal(root, System.out);
    }
}

XML:

Root(any=[[child: null]])
<?xml version="1.0" encoding="US-ASCII"?>
<parent>
   <child age="1" name="Child"/>
</parent>