CODEWITHSUNDEEP
javaxmldomxslt
mpc
mpc

Reputation: 79

java xsl template matching

Does anyone know of a neat way in java or any packages that will allow me to check if a Node in a DOM will match on a template in an xsl stylesheet.

For example;

<xsl:template match="elem/child/item">
   ...
</xsl:template>

Would be a template I'm looking for a match for using something like;

Node n = getNode();
String pattern = "elem/child/item"
boolean match = PatternMatcher.isMatch(n, pattern);

Of course where the pattern used could be any sort of XPath expression that could be used as a template match in an xsl stylesheet.

I would greatly appreciate it if anyone knows a nice way this could be acheived through packages etc. Thanks

Upvotes: 1

Views: 579

Answers (4)

prunge
prunge

Reputation: 23248

Is Java's XPath API what you need?

InputSource source = new InputSource(new FileInputStream("myfile.xml"));
//Document source = ...; //or use a DOM document as the source

String expression = "//elem/child/item"; //XPath expression

XPath xPath = XPathFactory.newInstance().newXPath();
NodeList matches = (NodeList)xPath.evaluate(expression, source, XPathConstants.NODESET);
System.out.println("Match count: " + matches.getLength());

Upvotes: 0

Dimitre Novatchev
Dimitre Novatchev

Reputation: 243449

Use:

//elem/child/item

this selects exactly all nodes in the XML document that are matched by the match pattern elem/child/item.

To verify that a given node $n is matched by the template, use this XPath expression:

count($n | //elem/child/item) = count(//elem/child/item)

Alternatively (and this may be more efficient):

$n[self::item 
 and 
  parent::node()
     [self::child 
    and 
      parent::node()
         [self::elem]
     ] 
   ]

Do note, the fact that a node is matched by a match-pattern doesn't mean that the template will be selected for processing this node (or that any template will be selected at all). Selection of template for processing depends on the existing <xsl:apply-templates>, on whether there are other templates with higher import precedence or priority that also match the same node.

Upvotes: 0

Michael Kay
Michael Kay

Reputation: 163322

Saxon's XPathCompiler object:

http://www.saxonica.com/documentation/javadoc/net/sf/saxon/s9api/XPathCompiler.html

has a method compilePattern() that allows you to compile an XSLT Pattern. This is returned in the form of an XPathExecutable, which can be evaluated by (a) supplying the target node as the context node for evaluation, and (b) evaluating the expression to return a boolean which is true if the pattern matches the node or false otherwise.

Upvotes: 1

jtahlborn
jtahlborn

Reputation: 53694

Not super efficient, but you could simply run the xpath on the document and see if it returns the Node in question.

Upvotes: 1

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