Tutorials : XML Made Easy with XOM :

XML Made Easy with XOM

XOM is the acronym for XML Object Model and it was developed by Elliotte Rusty Harold as an alternative to the existing solutions for processing XML documents. It supports important technologies as XSLT, XPath, namespaces, XInclude, Canonical XML, and it depends on an underlying SAX parser to process XML documents. As Mr. Harold says: "XOM it is an open source (LGPL), tree-based API for processing XML with Java that strives for correctness, simplicity, and performance, in that order." You can add to these that XOM is small, very easy to install, and very flexible.

In this article, you will see how to:

Create XML with XOMSerialize XML with XOM
Parse and navigate into an XML with XOM
Validate an XML with XOM
Use a SAX parser with XOM
Use XPath with XOM
Use XSLT with XOM

Downloading and Installing XOM

To get started, download XOM.I recommend you download the complete zip package and extract it on your machine.

XOM is a JAR library named xom-1.1.jar that can be installed by copying it in the /ext directory of your Java distribution (or, you can put it in your classpath).

Creating an XML with XOM

It is absolutely amazing how easy it is to create a complex XML document with XOM! The best proof is to take some XML, like shown in Listing 1, and try to reproduce it through the XOM API.

As you can see, this XML (named AirWings_xml.xml) contains elements, attributes, namespaces, and a DTD declaration. Before generating this XML, is important to know how to:

Create the XML document with a root-element:

Element root = new Element("company");
Document doc = new Document(root);

Append a child-element to its parent:

Element companyname = new Element("company-name");   
companyname.appendChild("AirWings");
root.appendChild(companyname);

Create an attribute and add it to its owner:

Element flyfrom = new Element("fly-from");
Attribute year = new Attribute("year","2005");
flyfrom.addAttribute(year);

Create a namespace and an element that belongs to a namespace:

final String register = "http://www.airwings.org/register/";
Element companydetails = new Element("mc:company-details",register);

Create a DTD declaration:

DocType doctype = new DocType("company", "AirWings_xml.dtd");
doc.insertChild(doctype, 0);

Display the generated XML:

String result = doc.toXML();
System.out.println(result);

Now, put all these pieces together to generate the AirWings_xml.xml document (shown in Listing 2).

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