The term open source describes practices in production and development that promote access to the end product's source materials. Some consider open source a philosophy, others consider it a pragmatic methodology...
Java is a programming language originally developed by James Gosling at Sun Microsystems and released in 1995 as a core component of Sun Microsystems' Java platform. The language derives much of its syntax from C and C++ but has a simpler object model and fewer low-level facilities...
Extensible Markup Language is a set of rules for encoding documents in machine-readable form. It is defined in the XML 1.0 Specification produced by the W3C, and several other related specifications, all gratis open standards....
that was designed specifically for the Java platform so that it can take advantage of its language features. JDOM integrates with Document Object Model
Document Object Model
The Document Object Model is a cross-platform and language-independent convention for representing and interacting with objects in HTML, XHTML and XML documents. Aspects of the DOM may be addressed and manipulated within the syntax of the programming language in use...
SAX is an event-based sequential access parser API developed by the XML-DEV mailing list for XML documents. SAX provides a mechanism for reading data from an XML document that is an alternative to that provided by the Document Object Model...
XSLT is a declarative, XML-based language used for the transformation of XML documents. The original document is not changed; rather, a new document is created based on the content of an existing one. The new document may be serialized by the processor in standard XML syntax or in another format,...
. It uses external parsers to build documents. JDOM was developed by Jason Hunter and Brett McLaughlin starting in March 2000. It has been part of the Java Community Process
Java Community Process
The Java Community Process or JCP, established in 1998, is a formalized process that allows interested parties to get involved in the definition of future versions and features of the Java platform....
as JSR 102, though that effort has since been abandoned.
Examples
Suppose the file "foo.xml" contains this XML document:
One can parse the XML file into a tree of Java objects with JDOM, like so:
SAXBuilder builder = new SAXBuilder;
Document doc = builder.build(new FileInputStream("foo.xml"));
Element root = doc.getRootElement;
// root.getName is "shop"
// root.getAttributeValue("name") is "shop for geeks"
// root.getAttributeValue("location") is "Tokyo, Japan"
// root.getChildren is a java.util.List object that contains 3 Element objects.
In case you don't want to create the document object from any file or any input stream, you can create the document object against the element.
Element root = new Element("shop"); // here is the root
Document doc = new Document(root);
As a converse, one can construct a tree of elements, then generate a XML file from it, like:
Element root = new Element("shop");
root.setAttribute("name", "shop for geeks");
root.setAttribute("location", "Tokyo, Japan");
Element item1 = new Element("computer");
item1.setAttribute("name", "iBook");
item1.setAttribute("price", "1200$");
root.addContent(item1);
// do the similar for other elements
XMLOutputter outputter = new XMLOutputter;
outputter.output(new Document(root), new FileOutputStream ("foo2.xml"));
