Main.java Source code

Introduction

Here is the source code for Main.java

Source

import javax.xml.bind.JAXBContext;
import javax.xml.bind.Marshaller;
import javax.xml.bind.annotation.XmlRootElement;
import javax.xml.bind.annotation.XmlType;
import javax.xml.bind.annotation.adapters.XmlAdapter;
import javax.xml.bind.annotation.adapters.XmlJavaTypeAdapter;

public class Main {

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

        Root rootA = new Root();
        rootA.setName("A");

        Root rootB = new Root();
        rootB.setName("B");
        rootA.setChild(rootB);

        Root rootC = new Root();
        rootC.setName("C");
        rootB.setChild(rootC);

        Root rootD = new Root();
        rootD.setName("D");
        rootC.setChild(rootD);

        Root rootE = new Root();
        rootE.setName("E");
        rootD.setChild(rootE);

        Marshaller marshaller = jc.createMarshaller();
        marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);

        DepthListener depthListener = new DepthListener(3);
        marshaller.setListener(depthListener);
        marshaller.setAdapter(new RootAdapter(depthListener));
        marshaller.marshal(rootA, System.out);
    }

}

class DepthListener extends Marshaller.Listener {

    private int targetDepth;
    private int currentDepth = 0;

    public DepthListener(int depth) {
        this.targetDepth = depth;
    }

    @Override
    public void beforeMarshal(Object source) {
        currentDepth++;
    }

    @Override
    public void afterMarshal(Object source) {
        currentDepth--;
    }

    public boolean isMarshalDepth() {
        return currentDepth <= targetDepth;
    }

}

class RootAdapter extends XmlAdapter<Root, Root> {

    private DepthListener depthListener;

    public RootAdapter() {
    }

    public RootAdapter(DepthListener depthListener) {
        this.depthListener = depthListener;
    }

    @Override
    public Root unmarshal(Root root) throws Exception {
        return root;
    }

    @Override
    public Root marshal(Root root) throws Exception {
        if (depthListener != null && !depthListener.isMarshalDepth()) {
            return null;
        }
        return root;
    }

}

@XmlRootElement
@XmlJavaTypeAdapter(RootAdapter.class)
@XmlType(propOrder = { "name", "child" })
class Root {

    private String name;
    private Root child;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Root getChild() {
        return child;
    }

    public void setChild(Root report) {
        this.child = report;
    }

}