au.gov.nehta.common.utils

Class XPathUtils

java.lang.Object

au.gov.nehta.common.utils.XPathUtils

public final class XPathUtils
extends Object

Utility class containing XPath-related functions. These methods simplify the call to the method: javax.xml.xpath.XPath#evaluate(String, Object, QName).

Method Summary

Modifier and Type	Method and Description
static <T> T	evaluate(String xpath, Node contextNode, Map<String,String> namespaceMap, Class<T> expectedType) Evaluates an XPath expression over a DOM node and casts the result to a Java type.
static Object	evaluate(String xpath, Node contextNode, Map<String,String> namespaceMap, QName returnType) Evaluates an XPath expression over a DOM node.
static int	getCount(String xpath, Node contextNode, Map<String,String> namespaceMap) Evaluates an XPath expression over a DOM node and returns the count of DOM nodes that the expression evaluated to.
static List<Element>	getElementList(String xpath, Node contextNode, Map<String,String> namespaceMap) Evaluates an XPath expression to a list of Elements.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

evaluate

public static <T> T evaluate(String xpath,
                             Node contextNode,
                             Map<String,String> namespaceMap,
                             Class<T> expectedType)
                      throws XPathExpressionException

Evaluates an XPath expression over a DOM node and casts the result to a Java type.

Type Parameters:

T - Java type

Parameters:

xpath - XPath expression to evaluate. Cannot be null nor an empty string.

contextNode - DOM node to evaluate XPath over. Cannot be null.

namespaceMap - Mapping of namespace prefixes in XPath expression to namespace URIs.

expectedType - The Java type to cast the result object to. Cannot be null. Possible values are: java.lang.String.class (for a string value), java.lang.Boolean.class (for a boolean value), java.lang.Double.class (for a number value), org.w3c.dom.NodeList (for a node set), org.w3c.dom.Node (for a node value) or sub-classes of org.w3c.dom.Node (such as a DOM element).

Returns:

Result object that the XPath expression evaluates to.

Throws:

XPathExpressionException - Thrown when the XPath expression cannot be evaluated.

evaluate

public static Object evaluate(String xpath,
                              Node contextNode,
                              Map<String,String> namespaceMap,
                              QName returnType)
                       throws XPathExpressionException

Evaluates an XPath expression over a DOM node.

Parameters:

xpath - XPath expression to evaluate. Cannot be null nor an empty string.

contextNode - DOM node to evaluate XPath over. Cannot be null.

namespaceMap - Mapping of namespace prefixes in XPath expression to namespace URIs.

returnType - Expected type of result object. Cannot be null. The value must come from the XPathConstants class.

Returns:

Result object that the XPath expression evaluates to.

Throws:

XPathExpressionException - Thrown when the XPath expression cannot be evaluated.

getCount

public static int getCount(String xpath,
                           Node contextNode,
                           Map<String,String> namespaceMap)
                    throws XPathExpressionException

Evaluates an XPath expression over a DOM node and returns the count of DOM nodes that the expression evaluated to.

Parameters:

xpath - XPath expression to evaluate. Cannot be null nor an empty string.

contextNode - DOM node to evaluate XPath over. Cannot be null.

namespaceMap - Mapping of namespace prefixes in XPath expression to namespace URIs.

Returns:

Count of the DOM nodes that the XPath expression evaluates to.

Throws:

XPathExpressionException - Thrown when the XPath expression cannot be evaluated.

getElementList

public static List<Element> getElementList(String xpath,
                                           Node contextNode,
                                           Map<String,String> namespaceMap)
                                    throws XPathExpressionException

Evaluates an XPath expression to a list of Elements.

Parameters:

xpath - XPath expression to evaluate. Cannot be null nor an empty string.

contextNode - DOM node to evaluate XPath over. Cannot be null.

namespaceMap - Mapping of namespace prefixes in XPath expression to namespace URIs.

Returns:

List of elements the XPath expression evaluated to, or an empty list if none matching.

Throws:

XPathExpressionException - Thrown when the XPath expression cannot be evaluated.