Converting JTree to Xml in java

Question

I am working on JTree and i need to Create XML file of Jtree so is there any good way to convert it? I am using JTree in java. I just need to convert it and i have Checkbox as node into the Tree and i have used render for it. and when submit call i need to convert that Jtree into XML. is there any good way for that??

My Tree is Dynamically Created. so i need to convert it.

i tried this

try {
            DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
            Document doc = factory.newDocumentBuilder().newDocument();
            Element rootElement = doc.createElement("Vervesystems");

            TreeNode root = (TreeNode) jTree1.getModel().getRoot();

            parseTreeNode(root, rootElement);
            System.out.println("Node name"+root.toString());
            System.err.println("Root node"+root.getChildCount());

            Transformer tf = TransformerFactory.newInstance().newTransformer();
            tf.setOutputProperty(OutputKeys.INDENT, "yes");
            tf.setOutputProperty(OutputKeys.METHOD, "xml");
            tf.setOutputProperty("{http://xml.apache.org/xslt}indent-amount", "4");

            DOMSource domSource = new DOMSource(doc);
            StreamResult sr = new StreamResult(new File("/home/kishan/NetBeansProjects/03-02-2014-VISDashboard/src/com/verve/visdashboard/TreeModel.xml"));
            tf.transform(domSource, sr);


        } catch (Exception e) {
            System.err.println("This is exception "+e);

        }

private void parseTreeNode(TreeNode treeNode, Node doc) {
        try {
        Element parentElement = doc.getOwnerDocument().createElement("folder");
        doc.appendChild(parentElement);

        System.err.println("Element name"+parentElement.getTagName());

        // Apply properties to root element...
        org.w3c.dom.Attr attrName = doc.getOwnerDocument().createAttribute("DisplayName");
        attrName.setNodeValue("Treenode");
        System.err.println("Count"+treeNode.getChildCount());
        parentElement.getAttributes().setNamedItem(attrName);


        Enumeration kiddies = treeNode.children();

        while (kiddies.hasMoreElements()) {
            TreeNode child = (TreeNode) kiddies.nextElement();
            //doc.appendChild(child);
            System.out.println("Child"+child.toString());
            parseTreeNode(child, parentElement);
        }

        } catch (Exception e) {
            System.err.println("exception is here"+e);
        }

but its Wrting blank only in myxml file. can anybody give suggestion. Example image is here.

Answer 1

The basic concept is simple. A TreeModel is just a bunch of linked nodes, which may or may not contain children

Creating the XML is a "little" more complex, but not that difficult, in fact, the most difficult part would be trying to parse each node and saving it...

Take a look at Java API for XML Processing (JAXP) for more details

import java.io.File;
import java.util.Enumeration;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.swing.tree.DefaultTreeModel;
import javax.swing.tree.TreeModel;
import javax.swing.tree.TreeNode;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.transform.OutputKeys;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerConfigurationException;
import javax.xml.transform.TransformerException;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;
import org.w3c.dom.Attr;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;

public class ConvertToXML {

    public static void main(String[] args) {
        TreeModel model = new DefaultTreeModel(...);

        try {

            DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
            Document doc = factory.newDocumentBuilder().newDocument();
            Element rootElement = doc.createElement("treeModel");

            doc.appendChild(rootElement);

            // Get tree root...
            TreeNode root = (TreeNode) model.getRoot();

            parseTreeNode(root, rootElement);

            // Save the document to disk...

            Transformer tf = TransformerFactory.newInstance().newTransformer();
            tf.setOutputProperty(OutputKeys.INDENT, "yes");
            tf.setOutputProperty(OutputKeys.METHOD, "xml");
            tf.setOutputProperty("{http://xml.apache.org/xslt}indent-amount", "4");

            DOMSource domSource = new DOMSource(doc);
            StreamResult sr = new StreamResult(new File("TreeModel.xml"));
            tf.transform(domSource, sr);

        } catch (ParserConfigurationException | TransformerException ex) {
            ex.printStackTrace();
        }
    }

    private static void parseTreeNode(TreeNode treeNode, Node doc) {

        Element parentElement = doc.getOwnerDocument().createElement("node");
        doc.appendChild(parentElement);

        // Apply properties to root element...
        Attr attrName = doc.getOwnerDocument().createAttribute("name");
        attrName.setNodeValue(...);
        parentElement.getAttributes().setNamedItem(attrName);

        Enumeration kiddies = treeNode.children();
        while (kiddies.hasMoreElements()) {
            TreeNode child = (TreeNode) kiddies.nextElement();
            parseTreeNode(child, parentElement);
        }

    }

}

Updated with runnable example

The following example is based on the examples from How to use Trees

And produces the following output...

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<Library>
    <catagory name="Books for Java Programmers">
        <book name="The Java Tutorial: A Short Course on the Basics" url="tutorial.html"/>
        <book name="The Java Tutorial Continued: The Rest of the JDK" url="tutorialcont.html"/>
        <book name="The JFC Swing Tutorial: A Guide to Constructing GUIs" url="swingtutorial.html"/>
        <book name="Effective Java Programming Language Guide" url="bloch.html"/>
        <book name="The Java Programming Language" url="arnold.html"/>
        <book name="The Java Developers Almanac" url="chan.html"/>
    </catagory>
    <catagory name="Books for Java Implementers">
        <book name="The Java Virtual Machine Specification" url="vm.html"/>
        <book name="The Java Language Specification" url="jls.html"/>
    </catagory>
</Library>

The code...

import java.io.File;
import java.util.Enumeration;
import javax.swing.tree.DefaultMutableTreeNode;
import javax.swing.tree.DefaultTreeModel;
import javax.swing.tree.TreeModel;
import javax.swing.tree.TreeNode;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.transform.OutputKeys;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerException;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;
import org.w3c.dom.Attr;
import org.w3c.dom.Document;
import org.w3c.dom.Element;

public class TreeExample {

    public static void main(String[] args) {
        DefaultMutableTreeNode top = new DefaultMutableTreeNode("The Java Series");
        createNodes(top);
        TreeModel model = new DefaultTreeModel(top);

        try {

            DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
            Document doc = factory.newDocumentBuilder().newDocument();

            // Get tree root...
            DefaultMutableTreeNode root = (DefaultMutableTreeNode) model.getRoot();

            parseTreeNode(root, doc);

            // Save the document to disk...
            Transformer tf = TransformerFactory.newInstance().newTransformer();
            tf.setOutputProperty(OutputKeys.INDENT, "yes");
            tf.setOutputProperty(OutputKeys.METHOD, "xml");
            tf.setOutputProperty("{http://xml.apache.org/xslt}indent-amount", "4");

            DOMSource domSource = new DOMSource(doc);
            StreamResult sr = new StreamResult(new File("TreeModel.xml"));
            tf.transform(domSource, sr);

        } catch (ParserConfigurationException | TransformerException ex) {
            ex.printStackTrace();
        }
    }

    protected static void parseTreeNode(DefaultMutableTreeNode treeNode, Document doc) {

            String value = treeNode.getUserObject().toString();
            Element rootElement = doc.createElement("Library");
            doc.appendChild(rootElement);

            Enumeration kiddies = treeNode.children();
            while (kiddies.hasMoreElements()) {
                DefaultMutableTreeNode child = (DefaultMutableTreeNode) kiddies.nextElement();
                parseTreeNode(child, rootElement);
            }

    }

    protected static void parseTreeNode(DefaultMutableTreeNode treeNode, Element doc) {

        Object value = treeNode.getUserObject();

        Element parentElement = null;
        if (value instanceof BookInfo) {
            parentElement = doc.getOwnerDocument().createElement("book");

            BookInfo book = (BookInfo) value;
            // Apply properties to root element...
            Attr attrName = doc.getOwnerDocument().createAttribute("name");
            attrName.setNodeValue(book.getBookName());
            parentElement.getAttributes().setNamedItem(attrName);

            Attr attrURL = doc.getOwnerDocument().createAttribute("url");
            attrURL.setNodeValue(book.getBookURL());
            parentElement.getAttributes().setNamedItem(attrURL);
        } else if (value instanceof BookCatagory) {
            parentElement = doc.getOwnerDocument().createElement("catagory");

            BookCatagory book = (BookCatagory) value;
            // Apply properties to root element...
            Attr attrName = doc.getOwnerDocument().createAttribute("name");
            attrName.setNodeValue(book.getCatagory());
            parentElement.getAttributes().setNamedItem(attrName);
        }

        doc.appendChild(parentElement);

        Enumeration kiddies = treeNode.children();
        while (kiddies.hasMoreElements()) {
            DefaultMutableTreeNode child = (DefaultMutableTreeNode) kiddies.nextElement();
            parseTreeNode(child, parentElement);
        }
    }

    protected static void createNodes(DefaultMutableTreeNode top) {
        DefaultMutableTreeNode category = null;
        DefaultMutableTreeNode book = null;

        category = new DefaultMutableTreeNode(new BookCatagory("Books for Java Programmers"));
        top.add(category);

        //original Tutorial
        book = new DefaultMutableTreeNode(new BookInfo("The Java Tutorial: A Short Course on the Basics",
                "tutorial.html"));
        category.add(book);

        //Tutorial Continued
        book = new DefaultMutableTreeNode(new BookInfo("The Java Tutorial Continued: The Rest of the JDK",
                "tutorialcont.html"));
        category.add(book);

        //JFC Swing Tutorial
        book = new DefaultMutableTreeNode(new BookInfo("The JFC Swing Tutorial: A Guide to Constructing GUIs",
                "swingtutorial.html"));
        category.add(book);

        //Bloch
        book = new DefaultMutableTreeNode(new BookInfo("Effective Java Programming Language Guide",
                "bloch.html"));
        category.add(book);

        //Arnold/Gosling
        book = new DefaultMutableTreeNode(new BookInfo("The Java Programming Language", "arnold.html"));
        category.add(book);

        //Chan
        book = new DefaultMutableTreeNode(new BookInfo("The Java Developers Almanac",
                "chan.html"));
        category.add(book);

        category = new DefaultMutableTreeNode(new BookCatagory("Books for Java Implementers"));
        top.add(category);

        //VM
        book = new DefaultMutableTreeNode(new BookInfo("The Java Virtual Machine Specification",
                "vm.html"));
        category.add(book);

        //Language Spec
        book = new DefaultMutableTreeNode(new BookInfo("The Java Language Specification",
                "jls.html"));
        category.add(book);
    }

    public static class BookCatagory {

        private String catagory;

        public BookCatagory(String cat) {
            this.catagory = cat;
        }

        public String getCatagory() {
            return catagory;
        }

    }

    private static class BookInfo {

        private String bookName;
        private String bookURL;

        public BookInfo(String book, String filename) {
            bookName = book;
            bookURL = filename;
        }

        public String getBookName() {
            return bookName;
        }

        public String getBookURL() {
            return bookURL;
        }

        public String toString() {
            return bookName;
        }
    }
}

Answer 2

You should have your TreeModel implement Serializable and you can then use simple Java to convert to XML and read it back fairly simply:

XMLEncoder enc = new XMLEncoder(outputStream);
enc.writeObject(treeModelInstance);

and read it in:

XMLDecoder dec = new XMLDecoder(inputStream);
KrishnasTreeModel model = (KrishnasTreeModel)dec.readObject();

OP requested an XStream example, therefore:

public class Person {
  private String firstname;
  private String lastname;
  private PhoneNumber phone;
  private PhoneNumber fax;
  // ... constructors and methods
}

public class PhoneNumber {
  private int code;
  private String number;
  // ... constructors and methods
}

To serialize these:

Person joe = new Person("Joe", "Walnes");
joe.setPhone(new PhoneNumber(123, "1234-456"));
joe.setFax(new PhoneNumber(123, "9999-999"));
XStream xstream = new XStream();
String joeInXml = xstream.toXML(joe);

Deserialization is trivial:

Person otherJoe = xstream.fromXML(joeInXml);

Good luck and, if you should have further problems, do leave a comment. Do note that you don't necessarily need to implement Serializable to use XStream -- it doesn't care. If you should want to customise XStream to generate other XML, this is also possible using Annotations.