Building Oracle XML Applications

Searching XML Documents with XPath

In this section, we’ll work through several examples that illustrate the power and productivity offered by the Oracle XML Parser’s tightly integrated XPath support. Using these XPath capabilities, we’ll see how easy searching, extracting, evaluating, and retrieving the value of the nodes in an XML document can be, avoiding tons of tedious DOM node manipulation code.

Basic Use of XPath in Java

Oracle’s implementation of the Document Object Model extends the basic DOM APIs to provide some simple yet powerful additional methods that can save you lots of time when writing applications that process XML. These extensions come in the form of the following extra methods on the XMLNode object:

selectNodes (XPathExpr)

Returns a DOM NodeList containing the nodes matching an XPath expression

selectSingleNode (XPathExpr)

Returns the first DOM node matching an XPath expression

valueOf (XPathExpr)

Returns a String with the text value of the nodes matching an XPath expression

print (Writer | OutputStream )

Serializes the node and its children to an output stream as XML markup

These methods are all defined on the XMLNode class that implements the DOM Node interface in the Oracle XML Parser. Since XMLDocument extends from XMLNode, you can use any of these methods on an entire XML document, or just scope them to a particular node. Since the methods are not defined by the W3C’s base DOM interfaces, in order to call the methods you have to cast a Node object into ...