Main.java Source code

Introduction

Here is the source code for Main.java

Source

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import javax.xml.bind.JAXBContext;
import javax.xml.bind.Marshaller;
import javax.xml.bind.annotation.XmlAttribute;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;
import javax.xml.bind.annotation.adapters.XmlAdapter;
import javax.xml.bind.annotation.adapters.XmlJavaTypeAdapter;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMResult;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;
import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathConstants;
import javax.xml.xpath.XPathExpression;
import javax.xml.xpath.XPathFactory;

import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;

@XmlRootElement
public class Main {
    @XmlJavaTypeAdapter(MapXmlAdapter.class)
    @XmlElement(name = "map")
    private Map<String, String> data = new HashMap<>();

    public static void main(String[] args) throws Exception {
        Main example = new Main();
        example.data.put("France", "Paris");
        example.data.put("Japan", "Tokyo");

        JAXBContext context = JAXBContext.newInstance(Main.class);
        Marshaller marshaller = context.createMarshaller();
        DOMResult result = new DOMResult();
        marshaller.marshal(example, result);

        XPathFactory factory = XPathFactory.newInstance();
        XPath xpath = factory.newXPath();

        Document document = (Document) result.getNode();
        XPathExpression expression = xpath.compile("//map/entry");
        NodeList nodes = (NodeList) expression.evaluate(document, XPathConstants.NODESET);

        expression = xpath.compile("//map");
        Node oldMap = (Node) expression.evaluate(document, XPathConstants.NODE);
        Element newMap = document.createElement("map");

        for (int index = 0; index < nodes.getLength(); index++) {
            Element element = (Element) nodes.item(index);
            newMap.setAttribute(element.getAttribute("key"), element.getAttribute("value"));
        }

        expression = xpath.compile("//map/..");
        Node parent = (Node) expression.evaluate(document, XPathConstants.NODE);
        parent.replaceChild(newMap, oldMap);

        TransformerFactory.newInstance().newTransformer().transform(new DOMSource(document),
                new StreamResult(System.out));
    }
}

class MapXmlAdapter extends XmlAdapter<MyMap, Map<String, String>> {
    @Override
    public Map<String, String> unmarshal(MyMap value) throws Exception {
        throw new UnsupportedOperationException();
    }

    @Override
    public MyMap marshal(Map<String, String> value) throws Exception {
        MyMap map = new MyMap();
        map.entries = new ArrayList<MyEntry>();
        for (String key : value.keySet()) {
            MyEntry entry = new MyEntry();
            entry.key = key;
            entry.value = value.get(key);
            map.entries.add(entry);
        }
        return map;
    }
}

class MyMap {
    @XmlElement(name = "entry")
    public List<MyEntry> entries;
}

class MyEntry {
    @XmlAttribute
    public String key;

    @XmlAttribute
    public String value;
}