Processing XML - Java - page 806

Example 20-10. XPathDemo.java
/**
* Simple demo of XPath, supported in JAXP (in JavaSE package javax.xml.xpath)
*/
public public class class XPathDemo XPathDemo {

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

DocumentBuilder parser =
DocumentBuilderFactory . newInstance (). newDocumentBuilder ();

String doc = "<?xml version='1.0'?>" +
"<section><sectiontitle>A Discourse of Numbers</sectiontitle>" +
"<sectionnumber>1.2</sectionnumber>" +
"<SC>Introduction</SC><p></p></section>" ;

Document document =
parser . parse ( new

new ByteArrayInputStream ( doc . getBytes ()));

// Evaluate the XPath expression against the Document
XPath xpath = XPathFactory . newInstance (). newXPath ();
String expression = "/section/sectionnumber" ;
Number secNum = ( Number ) xpath . evaluate (
expression , document , XPathConstants . NUMBER );
System . out . printf ( "Section number = %s (a %s)" ,
secNum , secNum . getClass (). getName ());

}

}

Create a Document parser.

He re the input XML document is a hardcoded String.

Cr eate a Document from the XML document created in .

Cr eate an XPath execution wrapper.

Sp ecify the string to match; this says to find the sectionnumber element inside a sec-
tion element.

Fi nally, evaluate the XPath expression.