Java and XML: generating XML

DOM API:

import java.io.*;
import org.w3c.dom.*;
import javax.xml.parsers.*;
import javax.xml.transform.*;
import javax.xml.transform.stream.*;
import javax.xml.transform.dom.*;

public class Main {

 public static void main(String[] args) throws Exception {

  DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
  Document xmldoc = factory.newDocumentBuilder().getDOMImplementation().createDocument(null, "PhoneBook", null);

  Element root = xmldoc.getDocumentElement();
  Element e = xmldoc.createElementNS(null, "BookRecord");
  Node n = xmldoc.createTextNode("Value");
  e.appendChild(n);
  root.appendChild(e);

  Transformer serializer = TransformerFactory.newInstance().newTransformer();
  serializer.setOutputProperty(OutputKeys.INDENT,"yes");
  serializer.transform(new DOMSource(xmldoc), new StreamResult(new PrintWriter(System.out)));
 }
}


SAX API:

import java.io.PrintWriter;

import javax.xml.transform.OutputKeys;
import javax.xml.transform.sax.SAXTransformerFactory;
import javax.xml.transform.sax.TransformerHandler;
import javax.xml.transform.stream.StreamResult;

import org.xml.sax.helpers.*;

public class Main {

 public static void main(String argv[]) throws Exception {

  SAXTransformerFactory tf = (SAXTransformerFactory) SAXTransformerFactory.newInstance();
  TransformerHandler hd = tf.newTransformerHandler();
  hd.getTransformer().setOutputProperty(OutputKeys.INDENT,"yes");
  hd.setResult(new StreamResult(new PrintWriter( System.out)));

  hd.startDocument();
  hd.startElement("", "", "PhoneBook",new AttributesImpl());
  hd.startElement("", "","BookRecord", new AttributesImpl());
  hd.characters("Value".toCharArray(), 0, 5);
  hd.endElement("", "", "BookRecord");
  hd.endElement("", "", "PhoneBook");
  hd.endDocument();
 }
}


JDOM API:

package com;

import org.jdom.Document;
import org.jdom.Element;
import org.jdom.output.Format;
import org.jdom.output.XMLOutputter;

public class Main {

 public static void main(String argv[]) throws Exception {

  Document doc = new Document();
  Element e = new Element("PhoneBook");
  e.addContent(new Element("BookRecord").setText("Value"));
  doc.addContent(e);

  XMLOutputter outp = new XMLOutputter();
  Format f = Format.getPrettyFormat();
  //f.setIndent(" ");
  outp.setFormat(f);
  outp.output(doc, System.out);
 }
}


As result in all cases:

<?xml version="1.0" encoding="UTF-8"?>
<PhoneBook>
<BookRecord>Value</BookRecord>
</PhoneBook>

XML Serialization with java.beans.XMLEncoder class

import java.beans.XMLEncoder;

public class Main {

 public static void main(String[] args) throws Exception {
  XMLEncoder xenc = new XMLEncoder(System.out);
  xenc.writeObject("Some String");
  xenc.flush();
  xenc.close();
 }
}

Output:

<?xml version="1.0" encoding="UTF-8"?>
<java version="1.5.0_06" class="java.beans.XMLDecoder">
 <string>Some String</string>
</java>

Or more interesting:

import java.beans.XMLEncoder;

public class Main {

 public static void main(String[] args) throws Exception {

  Foo[] arr = {new Foo(), new Foo()};
  XMLEncoder encoder = new XMLEncoder(System.out);
  encoder.writeObject(arr);
  encoder.close();
  }

  public static class Foo {

  private int foo = 10 ;
  public int getFoo() {
   return foo;
  }

  public void setFoo(int foo) {
   this.foo = foo;
  }
 }
}


<?xml version="1.0" encoding="UTF-8"?>
<java version="1.5.0_06" class="java.beans.XMLDecoder">
 <array class="com.Main$Foo" length="2">
  <void index="0">
   <object class="com.Main$Foo"/>
  </void>
  <void index="1">
   <object class="com.Main$Foo"/>
  </void>
 </array>
</java>

As you can see - not so optimistic. For the things to be serialized propery, you need bean pattern getter methods, and sometimes even setters: so for simple java bean serialization will work fine.


XStream - a lightweight open source Java library for serializing Java objects to XML and back again.


import com.thoughtworks.xstream.XStream;

public class Main {

 public static void main(String[] args) throws Exception {

  XStream xstream = new XStream();
  xstream.alias("Foo", Foo.class);
  String xml = xstream.toXML(new Foo());
  System.out.println(xml);
 }

 public static class Foo {

  public int fooInt = 10 ;
  public String fooStr = "20";
  }
}


<Foo>
 <fooInt>10</fooInt>
 <fooStr>20</fooStr>
</Foo>

In case of List it behave too pretty good:

 List<Foo> list = new LinkedList<Foo>();
 list.add(new Foo());
 list.add(new Foo());
 String xml = xstream.toXML(list);

Result:

<linked-list>
 <Foo>
  <fooInt>10</fooInt>
  <fooStr>20</fooStr>
 </Foo>
 <Foo>
  <fooInt>10</fooInt>
  <fooStr>20</fooStr>
 </Foo>
</linked-list>