Core Java™ 2 Volume II - Advanced Features, Seventh Edition

Locating Information with XPath

If you want to locate a specific piece of information in an XML document, then it can be a bit of a hassle to navigate the nodes of the DOM tree. The XPath language makes it simple to access tree nodes. For example, suppose you have this XML document:

<configuration>
   . . .
   <database>
      <username>dbuser</username>
      <password>secret</password>
      . . .
   </database>
</configuration>

You can get the database user name by evaluating the XPath expression

/configuration/database/username

That's a lot simpler than the plain DOM approach:

1. Get the document node.

2. Enumerate its children.

3. Locate the database element.

4. Get its first child, the username element.

5. Get its first child, a Text node.

6. Get its data.

An XPath can describe a set ...