javax.xml.xpath
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. |
Since: 1.5
Version: $Revision: 226183 $, $Date: 2005-04-08 06:39:14 -0400 (Fri, 08 Apr 2005) $
See Also: XML Path Language (XPath) Version 1.0
Method Summary | |
---|---|
XPathExpression | compile(String expression) Compile an XPath expression for later evaluation. If |
Object | evaluate(String expression, Object item, QName returnType) Evaluate an See Evaluation of XPath Expressions for context item evaluation,
variable, function and If If a |
String | evaluate(String expression, Object item) Evaluate an XPath expression in the specified context and return the result as a This method calls {@link #evaluate(String expression, Object item, QName returnType)} with a See Evaluation of XPath Expressions for context item evaluation, variable, function and QName resolution and return type conversion. If a |
Object | evaluate(String expression, InputSource source, QName returnType) Evaluate an XPath expression in the context of the specified 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 If |
String | evaluate(String expression, InputSource source) Evaluate an XPath expression in the context of the specified This method calls {@link #evaluate(String expression, InputSource source, QName returnType)} with a
See Evaluation of XPath Expressions for context item evaluation, variable, function and QName resolution and return type conversion. If |
NamespaceContext | getNamespaceContext() Return the current namespace context.
|
XPathFunctionResolver | getXPathFunctionResolver() Return the current function resolver.
|
XPathVariableResolver | getXPathVariableResolver() Return the current variable resolver.
|
void | reset() Reset this
|
void | setNamespaceContext(NamespaceContext nsContext) Establish a namespace context. A |
void | setXPathFunctionResolver(XPathFunctionResolver resolver) Establish a function resolver. A |
void | setXPathVariableResolver(XPathVariableResolver resolver) Establish a variable resolver. A |
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
is null
, a NullPointerException
is thrown.
Parameters: expression The XPath expression.
Returns: Compiled XPath expression.
Throws: XPathExpressionException If expression
cannot be compiled. NullPointerException If expression
is null
.
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.
Parameters: expression The XPath expression. item The starting context (node or node list, for example). returnType The desired return type.
Returns: Result of evaluating an XPath expression as an Object
of returnType
.
Throws: XPathExpressionException If expression
cannot be evaluated. IllegalArgumentException If returnType
is not one of the types defined in {@link XPathConstants}. NullPointerException If expression
or returnType
is null
.
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.
Parameters: expression The XPath expression. item The starting context (node or node list, for example).
Returns: The String
that is the result of evaluating the expression and
converting the result to a String
.
Throws: XPathExpressionException If expression
cannot be evaluated. NullPointerException If expression
is null
.
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.
Parameters: expression The XPath expression. source The input source of the document to evaluate over. returnType The desired return type.
Returns: The Object
that encapsulates the result of evaluating the expression.
Throws: XPathExpressionException If expression cannot be evaluated. IllegalArgumentException If returnType
is not one of the types defined in {@link XPathConstants}. NullPointerException If expression
, source
or returnType
is null
.
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.
Parameters: expression The XPath expression. source The InputSource
of the document to evaluate over.
Returns: The String
that is the result of evaluating the expression and
converting the result to a String
.
Throws: XPathExpressionException If expression cannot be evaluated. NullPointerException If expression
or source
is null
.
Return the current namespace context.
null
is returned in no namespace context is in effect.
Returns: Current Namespace context.
Return the current function resolver.
null
is returned in no function resolver is in effect.
Returns: Current function resolver.
Return the current variable resolver.
null
is returned in no variable resolver is in effect.
Returns: Current variable resolver.
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 XPath
s
thus saving resources associated with the creation of new XPath
s.
The reset XPath
is not guaranteed to have the same {@link XPathFunctionResolver}, {@link XPathVariableResolver}
or {@link NamespaceContext} Object
s, e.g. {@link Object#equals(Object obj)}.
It is guaranteed to have a functionally equal XPathFunctionResolver
, XPathVariableResolver
and NamespaceContext
.
Establish a namespace context.
A NullPointerException
is thrown if nsContext
is null
.
Parameters: nsContext Namespace context to use.
Throws: NullPointerException If nsContext
is null
.
Establish a function resolver.
A NullPointerException
is thrown if resolver
is null
.
Parameters: resolver XPath function resolver.
Throws: NullPointerException If resolver
is null
.
Establish a variable resolver.
A NullPointerException
is thrown if resolver
is null
.
Parameters: resolver Variable resolver.
Throws: NullPointerException If resolver
is null
.