javax.xml.xpath.XPath |
XPath
provides access to the XPath evaluation environment and expressions.
Evaluation of XPath Expressions. | |
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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
XPathVariableResolver
set with
setXPathVariableResolver(XPathVariableResolver)
.
An
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
XPathFunctionResolver
set with
setXPathFunctionResolver(XPathFunctionResolver)
.
An
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
setNamespaceContext(NamespaceContext)
.
|
result |
This result of evaluating an expression is converted to an instance of the desired return type.
Valid return types are defined in
XPathConstants
.
Conversion to the return type follows XPath conversion rules.
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Public Methods | |||||||||||
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Compile an XPath expression for later evaluation. |
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Evaluate an XPath expression in the context of the specified
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Evaluate an XPath expression in the context of the specified
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Evaluate an XPath expression in the specified context and return the result as a
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Evaluate an
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Return the current namespace context. |
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Return the current function resolver. |
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Return the current variable resolver. |
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Reset this
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Establish a namespace context. |
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Establish a function resolver. |
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Establish a variable resolver. |
Compile an XPath expression for later evaluation.
If
expression
contains any
XPathFunction
s,
they must be available via the
XPathFunctionResolver
.
An
XPathExpressionException
will be thrown if the
XPathFunction
cannot be resolved with the
XPathFunctionResolver
.
If
expression
is
null
, a
NullPointerException
is thrown.
expression | The XPath expression. |
---|
XPathExpressionException |
If
expression
cannot be compiled.
|
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NullPointerException |
If
expression
is
null
.
|
Evaluate an XPath expression in the context of the specified
InputSource
and return the result as a
String
.
This method calls
evaluate(String, InputSource, QName)
with a
returnType
of
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. |
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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. |
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NullPointerException |
If
expression
or
source
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
InputSource
and calls
evaluate(String, Object, QName)
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
XPathConstants
,
then an
IllegalArgumentException
is thrown.
If
expression
,
source
or
returnType
is
null
,
then a
NullPointerException
is thrown.
expression | The XPath expression. |
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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. |
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IllegalArgumentException |
If
returnType
is not one of the types defined in
XPathConstants
.
|
NullPointerException |
If
expression
,
source
or
returnType
is
null
.
|
Evaluate an XPath expression in the specified context and return the result as a
String
.
This method calls
evaluate(String, Object, QName)
with a
returnType
of
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. |
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item | The starting context (node or node list, for example). |
String
that is the result of evaluating the expression and
converting the result to a
String
.
XPathExpressionException |
If
expression
cannot be evaluated.
|
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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
XPathConstants
(
NUMBER
,
STRING
,
BOOLEAN
,
NODE
or
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. |
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item | The starting context (node or node list, for example). |
returnType | The desired return type. |
Object
of
returnType
.
XPathExpressionException |
If
expression
cannot be evaluated.
|
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IllegalArgumentException |
If
returnType
is not one of the types defined in
XPathConstants
.
|
NullPointerException |
If
expression
or
returnType
is
null
.
|
Return the current namespace context.
null
is returned in no namespace context is in effect.
Return the current function resolver.
null
is returned in no function resolver is in effect.
Return the current variable resolver.
null
is returned in no variable resolver is in effect.
Reset this
XPath
to its original configuration.
XPath
is reset to the same state as when it was created with
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
XPathFunctionResolver
,
XPathVariableResolver
or
NamespaceContext
Object
s, e.g.
equals(Object)
.
It is guaranteed to have a functionally equal
XPathFunctionResolver
,
XPathVariableResolver
and
NamespaceContext
.
Establish a namespace context.
A
NullPointerException
is thrown if
nsContext
is
null
.
nsContext | Namespace context to use. |
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NullPointerException |
If
nsContext
is
null
.
|
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Establish a function resolver.
A
NullPointerException
is thrown if
resolver
is
null
.
resolver | XPath function resolver. |
---|
NullPointerException |
If
resolver
is
null
.
|
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Establish a variable resolver.
A
NullPointerException
is thrown if
resolver
is
null
.
resolver | Variable resolver. |
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NullPointerException |
If
resolver
is
null
.
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