Evaluating XPath Expressions using s9api
The s9api interface is a newly designed interface allowing integrated access to all
Saxon's XML processing capabilities in a uniform way, taking advantage of the type safety
offered by generics in Java 5.
You can evaluate an XPath expression using the s9api interface as follows:
Create a Processor (
net.sf.saxon.s9api.Processor) and set any global
configuration options on the Processor.
Build the source document by calling
newDocumentBuilder() to create a document builder,
setting appropriate options, and then calling the
build() method. This returns an
which can be supplied as the context item to the XPath expression.
newXPathCompiler() to create an XPath Compiler, and set any options that are local to a specific
compilation (notably declaring namespace prefixes that are used in the XPath expression).
compile() method to compile an expression. The result is an
which can be used as often as you like in the same thread or in different threads.
To evaluate the expression, call the
load() method on the
XPathExecutable. This creates
XPathSelector can be serially reused, but it must not be shared across
multiple threads. Set any options required for the specific XPath execution (for example, the initial context node, the
values of any variables referenced in the expression), and then call one of the methods
evaluateSingle() to execute the XPath expression.
XPathSelector is an
Iterable, it is possible to iterate over the results
directly using the Java 5 "for-each" construct.
The result of an XPath expression is in general an
XdmValue, representing a value as defined in the
XDM data model (that is, a sequence of nodes and/or atomic values). Subclasses of
XdmAtomicValue, and these relate directly to the corresponding
concepts in XDM. Various methods are available to translate between this model and native Java data types.
Examples of s9api XPath expressions are included in the Saxon resources file, see module S9APIExamples.java.