Pratik Shelar Pratik Shelar - 4 months ago 51
Java Question

Unmarshalling an XML using Xpath expression and jaxb

I am new to JAXB and would like to know if there is a way by which I can unmarshall an XML to my response object but using xpath expressions. The issue is that I am calling a third party webservice and the response which I receive has a lot of details. I do not wish to map all the details in the XML to my response object. I just wish to map few details from the xml using which I can get using specific XPath expressions and map those to my response object. Is there an annotation which can help me achieve this?

For example consider the following response

<root>
<record>
<id>1</id>
<name>Ian</name>
<AddressDetails>
<street> M G Road </street>
</AddressDetails>
</record>
</root>


I am only intrested in retrieving the street name so I want to use xpath expression to get value of street using 'root/record/AddressDetails/street' and map it to my response object

public class Response{
// How do i map this in jaxb, I do not wish to map record,id or name elements
String street;

//getter and setters
....
}


Thanks

Answer

Note: I'm the EclipseLink JAXB (MOXy) lead and a member of the JAXB (JST-222) expert group.

You could use MOXy's @XmlPath extension for this use case:

Response

import javax.xml.bind.annotation.*;
import org.eclipse.persistence.oxm.annotations.XmlPath;

@XmlRootElement(name="root")
@XmlAccessorType(XmlAccessType.FIELD)
public class Response{
    @XmlPath("record/AddressDetails/street/text()")
    String street; 

    //getter and setters
}

jaxb.properties

To use 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

import java.io.File;
import javax.xml.bind.*;

public class Demo {

    public static void main(String[] args) throws Exception {
        JAXBContext jc = JAXBContext.newInstance(Response.class);

        Unmarshaller unmarshaller = jc.createUnmarshaller();
        File xml = new File("src/forum17141154/input.xml");
        Response response = (Response) unmarshaller.unmarshal(xml);

        Marshaller marshaller = jc.createMarshaller();
        marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
        marshaller.marshal(response, System.out);
    }

}

Output

<?xml version="1.0" encoding="UTF-8"?>
<root>
   <record>
      <AddressDetails>
         <street> M G Road </street>
      </AddressDetails>
   </record>
</root>

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