31.4. XPath Builder
Overview
The
org.apache.camel.builder.xml.XPathBuilder class enables you to evaluate XPath expressions independently of an exchange. That is, if you have an XML fragment from any source, you can use XPathBuilder to evaluate an XPath expression on the XML fragment.
Matching expressions
Use the
matches() method to check whether one or more XML nodes can be found that match the given XPath expression. The basic syntax for matching an XPath expression using XPathBuilder is as follows:
boolean matches = XPathBuilder
.xpath("Expression")
.matches(CamelContext, "XMLString");
Where the given expression, Expression, is evaluated against the XML fragment, XMLString, and the result is true, if at least one node is found that matches the expression. For example, the following example returns
true, because the XPath expression finds a match in the xyz attribute.
boolean matches = XPathBuilder
.xpath("/foo/bar/@xyz")
.matches(getContext(), "<foo><bar xyz='cheese'/></foo>"));Evaluating expressions
Use the
evaluate() method to return the contents of the first node that matches the given XPath expression. The basic syntax for evaluating an XPath expression using XPathBuilder is as follows:
String nodeValue = XPathBuilder
.xpath("Expression")
.evaluate(CamelContext, "XMLString");
You can also specify the result type by passing the required type as the second argument to
evaluate()—for example:
String name = XPathBuilder
.xpath("foo/bar")
.evaluate(context, "<foo><bar>cheese</bar></foo>", String.class);
Integer number = XPathBuilder
.xpath("foo/bar")
.evaluate(context, "<foo><bar>123</bar></foo>", Integer.class);
Boolean bool = XPathBuilder
.xpath("foo/bar")
.evaluate(context, "<foo><bar>true</bar></foo>", Boolean.class);