Jaxb suppresses external tag for nested objects

Question

I have a complex object that I return as the return value from the usual "API in which I do not control."

For some API calls, the returned XML looks like this:

<APICall1>
  <VeryComplexObject>
    <VeryComplexObjectElements... >
  </VeryComplexObject>
</APICall1>

No problem, I just use

@XmlElement
private VeryComplexObject VeryComplexObject;

and this is as usual.

But a few challenges want to return:

<APICall2>
    <VeryComplexObjectElements... >
</APICall2>

Is there an annotation that I can use to suppress tags <VeryComplexObject>for unmarshal, but get tags from an internal element?

Answer 1

You can use JAXB with StAX to accomplish this, using StreamFilterto ignore the XML element:

package forum8526002;

import java.io.StringReader;

import javax.xml.bind.*;
import javax.xml.bind.annotation.*;
import javax.xml.stream.*;

public class Demo {

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

        XMLInputFactory xif = XMLInputFactory.newFactory();
        StringReader xml = new StringReader("<APICall2><VeryComplexObjectElements><Bar>Hello World</Bar></VeryComplexObjectElements></APICall2>");
        XMLStreamReader xsr = xif.createXMLStreamReader(xml);
        xsr = xif.createFilteredReader(xsr, new Filter());

        Unmarshaller unmarshaller = jc.createUnmarshaller();
        Foo foo = (Foo) unmarshaller.unmarshal(xsr);

        Marshaller marshaller = jc.createMarshaller();
        marshaller.marshal(foo, System.out);
    }

    @XmlRootElement(name="APICall2")
    static class Foo {

        @XmlElement(name="Bar")
        private String bar;

    }

    static class Filter implements StreamFilter {

        @Override
        public boolean accept(XMLStreamReader reader) {
            return !(reader.isStartElement() && reader.getLocalName().equals("VeryComplexObjectElements"));
        }

    }

}