org.springframework.xml.xpath

Interface XPathExpression

public interface XPathExpression

Defines the contract for a precompiled XPath expression. Concrete instances can be obtained through the XPathExpressionFactory.

Implementations of this interface are precompiled, and thus faster, but less flexible, than the XPath expressions used by XPathOperations implementations.

Since:

1.0.0

Author:

Arjen Poutsma

Method Summary

Modifier and Type	Method and Description
<T> List<T>	evaluate(Node node, NodeMapper<T> nodeMapper) Evaluates the given expression, mapping each result Node objects to a Java object via a NodeMapper.
boolean	evaluateAsBoolean(Node node) Evaluates the given expression as a boolean.
Node	evaluateAsNode(Node node) Evaluates the given expression as a Node.
List<Node>	evaluateAsNodeList(Node node) Evaluates the given expression, and returns all Node objects that conform to it.
double	evaluateAsNumber(Node node) Evaluates the given expression as a number (double).
<T> T	evaluateAsObject(Node node, NodeMapper<T> nodeMapper) Evaluates the given expression, mapping a single Node result to a Java object via a NodeMapper.
String	evaluateAsString(Node node) Evaluates the given expression as a String.

Method Detail

evaluateAsBoolean

boolean evaluateAsBoolean(Node node)
                   throws XPathException

Evaluates the given expression as a boolean. Returns the boolean evaluation of the expression, or false if it is invalid.

The return value is determined per the boolean() function defined in the XPath specification. This means that an expression that selects zero nodes will return false, while an expression that selects one or more nodes will return true. An expression that returns a string returns false for empty strings and true for all other strings. An expression that returns a number returns false for zero and true for non-zero numbers.

Parameters:

node - the starting point

Returns:

the result of the evaluation

Throws:

XPathException - in case of XPath errors

See Also:

XPath specification - boolean() function

evaluateAsNode

Node evaluateAsNode(Node node)
             throws XPathException

Evaluates the given expression as a Node. Returns the evaluation of the expression, or null if it is invalid.

Parameters:

node - the starting point

Returns:

the result of the evaluation

Throws:

XPathException - in case of XPath errors

See Also:

XPath specification

evaluateAsNodeList

List<Node> evaluateAsNodeList(Node node)
                       throws XPathException

Evaluates the given expression, and returns all Node objects that conform to it. Returns an empty list if no result could be found.

Parameters:

node - the starting point

Returns:

a list of Nodes that are selected by the expression

Throws:

XPathException - in case of XPath errors

See Also:

XPath specification

evaluateAsNumber

double evaluateAsNumber(Node node)
                 throws XPathException

Evaluates the given expression as a number (double). Returns the numeric evaluation of the expression, or Double.NaN if it is invalid.

The return value is determined per the number() function as defined in the XPath specification. This means that if the expression selects multiple nodes, it will return the number value of the first node.

Parameters:

node - the starting point

Returns:

the result of the evaluation

Throws:

XPathException - in case of XPath errors

See Also:

XPath specification - number() function

evaluateAsString

String evaluateAsString(Node node)
                 throws XPathException

Evaluates the given expression as a String. Returns null if no result could be found.

The return value is determined per the string() function as defined in the XPath specification. This means that if the expression selects multiple nodes, it will return the string value of the first node.

Parameters:

node - the starting point

Returns:

the result of the evaluation

Throws:

XPathException - in case of XPath errors

See Also:

XPath specification - string() function

evaluateAsObject

<T> T evaluateAsObject(Node node,
                       NodeMapper<T> nodeMapper)
                throws XPathException

Evaluates the given expression, mapping a single Node result to a Java object via a NodeMapper.

Parameters:

node - the starting point

nodeMapper - object that will map one object per node

Returns:

the single mapped object

Throws:

XPathException - in case of XPath errors

See Also:

XPath specification

evaluate

<T> List<T> evaluate(Node node,
                     NodeMapper<T> nodeMapper)
              throws XPathException

Evaluates the given expression, mapping each result Node objects to a Java object via a NodeMapper.

Parameters:

node - the starting point

nodeMapper - object that will map one object per node

Returns:

the result list, containing mapped objects

Throws:

XPathException - in case of XPath errors

See Also:

XPath specification