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XPathFactory factory = …;
XPath xpath = factory.newXPath();
Based on 169 examples
public interface XPath
XPath provides access to the XPath evaluation environment and expressions.
| Evaluation of XPath Expressions. | |
|---|---|
| context | If a request is made to evaluate the expression in the absence of a context item, an empty document node will be used for the context. For the purposes of evaluating XPath expressions, a DocumentFragment is treated like a Document node. |
| variables |
If the expression contains a variable reference, its value will be found through the {@link XPathVariableResolver}
set with {@link #setXPathVariableResolver(XPathVariableResolver resolver)}.
An {@link XPathExpressionException} is raised if the variable resolver is undefined or
the resolver returns null for the variable.
The value of a variable must be immutable through the course of any single evaluation.
|
| functions |
If the expression contains a function reference, the function will be found through the {@link XPathFunctionResolver}
set with {@link #setXPathFunctionResolver(XPathFunctionResolver resolver)}.
An {@link XPathExpressionException} is raised if the function resolver is undefined or
the function resolver returns null for the function.
|
| QNames | QNames in the expression are resolved against the XPath namespace context set with {@link #setNamespaceContext(NamespaceContext nsContext)}. |
| result | This result of evaluating an expression is converted to an instance of the desired return type. Valid return types are defined in {@link XPathConstants}. Conversion to the return type follows XPath conversion rules. |
An XPath object is not thread-safe and not reentrant.
In other words, it is the application's responsibility to make
sure that one {@link XPath} object is not used from
more than one thread at any given time, and while the evaluate
method is invoked, applications may not recursively call
the evaluate method.
| Method Summary | |
|---|---|
XPathExpression |
Compile an XPath expression for later evaluation. |
String |
evaluate(String expression, InputSource source)Evaluate an XPath expression in the context of the specified InputSource
and return the result as a String.
|
Object |
evaluate(String expression, InputSource source, QName returnType)Evaluate an XPath expression in the context of the specified InputSource
and return the result as the specified type.
|
String |
Evaluate an XPath expression in the specified context and return the result as a String.
|
Object |
Evaluate an XPath expression in the specified context and return the result as the specified type.
|
NamespaceContext |
Return the current namespace context. |
XPathFunctionResolver |
Return the current function resolver. |
XPathVariableResolver |
Return the current variable resolver. |
void |
reset()Reset this XPath to its original configuration.
|
void |
setNamespaceContext(NamespaceContext nsContext)Establish a namespace context. |
void |
Establish a function resolver. |
void |
Establish a variable resolver. |
| Method Detail |
|---|
public XPathExpression compile(String expression)
throws XPathExpressionException
Compile an XPath expression for later evaluation.
If expression contains any {@link XPathFunction}s,
they must be available via the {@link XPathFunctionResolver}.
An {@link XPathExpressionException} will be thrown if the
XPathFunction
cannot be resovled with the XPathFunctionResolver.
If expression contains any variables, the
{@link XPathVariableResolver} in effect
at compile time will be used to resolve them.
If expression is null, a NullPointerException is thrown.
expression - The XPath expression.XPathExpressionException - If expression cannot be compiled.public String evaluate(String expression,
InputSource source)
throws XPathExpressionException
Evaluate an XPath expression in the context of the specified InputSource
and return the result as a String.
This method calls {@link #evaluate(String expression, InputSource source, QName returnType)} with a
returnType of {@link XPathConstants#STRING}.
See Evaluation of XPath Expressions for context item evaluation, variable, function and QName resolution and return type conversion.
If expression or source is null,
then a NullPointerException is thrown.
expression - The XPath expression.source - The InputSource of the document to evaluate over.String that is the result of evaluating the expression and
converting the result to a String.XPathExpressionException - If expression cannot be evaluated.public Object evaluate(String expression,
InputSource source,
QName returnType)
throws XPathExpressionException
Evaluate an XPath expression in the context of the specified InputSource
and return the result as the specified type.
This method builds a data model for the {@link InputSource} and calls {@link #evaluate(String expression, Object item, QName returnType)} on the resulting document object.
See Evaluation of XPath Expressions for context item evaluation, variable, function and QName resolution and return type conversion.
If returnType is not one of the types defined in {@link XPathConstants},
then an IllegalArgumentException is thrown.
If expression, source or returnType is null,
then a NullPointerException is thrown.
expression - The XPath expression.source - The input source of the document to evaluate over.returnType - The desired return type.Object that encapsulates the result of evaluating the expression.XPathExpressionException - If expression cannot be evaluated.public String evaluate(String expression,
Object item)
throws XPathExpressionException
Evaluate an XPath expression in the specified context and return the result as a String.
This method calls {@link #evaluate(String expression, Object item, QName returnType)} with a returnType of
{@link XPathConstants#STRING}.
See Evaluation of XPath Expressions for context item evaluation, variable, function and QName resolution and return type conversion.
If a null value is provided for
item, an empty document will be used for the
context.
If expression is null, then a NullPointerException is thrown.
expression - The XPath expression.item - The starting context (a node, for example).String that is the result of evaluating the expression and
converting the result to a String.XPathExpressionException - If expression cannot be evaluated.public Object evaluate(String expression,
Object item,
QName returnType)
throws XPathExpressionException
Evaluate an XPath expression in the specified context and return the result as the specified type.
See Evaluation of XPath Expressions for context item evaluation,
variable, function and QName resolution and return type conversion.
If returnType is not one of the types defined in {@link XPathConstants} (
{@link XPathConstants#NUMBER NUMBER},
{@link XPathConstants#STRING STRING},
{@link XPathConstants#BOOLEAN BOOLEAN},
{@link XPathConstants#NODE NODE} or
{@link XPathConstants#NODESET NODESET})
then an IllegalArgumentException is thrown.
If a null value is provided for
item, an empty document will be used for the
context.
If expression or returnType is null, then a
NullPointerException is thrown.
expression - The XPath expression.item - The starting context (a node, for example).returnType - The desired return type.Object of returnType.XPathExpressionException - If expression cannot be evaluated.public NamespaceContext getNamespaceContext()
Return the current namespace context.
null is returned in no namespace context is in effect.
public XPathFunctionResolver getXPathFunctionResolver()
Return the current function resolver.
null is returned in no function resolver is in effect.
public XPathVariableResolver getXPathVariableResolver()
Return the current variable resolver.
null is returned in no variable resolver is in effect.
public void reset()
Reset this XPath to its original configuration.
XPath is reset to the same state as when it was created with
{@link XPathFactory#newXPath()}.
reset() is designed to allow the reuse of existing XPaths
thus saving resources associated with the creation of new XPaths.
The reset XPath is not guaranteed to have the same {@link XPathFunctionResolver}, {@link XPathVariableResolver}
or {@link NamespaceContext} Objects, e.g. {@link Object#equals(Object obj)}.
It is guaranteed to have a functionally equal XPathFunctionResolver, XPathVariableResolver
and NamespaceContext.
public void setNamespaceContext(NamespaceContext nsContext)
Establish a namespace context.
A NullPointerException is thrown if nsContext is null.
nsContext - Namespace context to use.public void setXPathFunctionResolver(XPathFunctionResolver resolver)
Establish a function resolver.
A NullPointerException is thrown if resolver is null.
resolver - XPath function resolver.public void setXPathVariableResolver(XPathVariableResolver resolver)
Establish a variable resolver.
A NullPointerException is thrown if resolver is null.
resolver - Variable resolver.
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