Interface XPathExpression
XPathExpression
provides access to compiled XPath 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 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 .
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. |
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.
|
- Since:
- 1.5
- Version:
- $Revision: 446598 $, $Date: 2006-09-15 15:55:40 +0300 (Fri, 15 Sep 2006) $
- Author:
- Norman Walsh, Jeff Suttor
- See Also:
-
Method Summary
Modifier and TypeMethodDescriptionEvaluate the compiled XPath expression in the specified context and return the result as aString
.Evaluate the compiled XPath expression in the specified context and return the result as the specified type.evaluate
(InputSource source) Evaluate the compiled XPath expression in the context of the specifiedInputSource
and return the result as aString
.evaluate
(InputSource source, QName returnType) Evaluate the compiled XPath expression in the context of the specifiedInputSource
and return the result as the specified type.
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Method Details
-
evaluate
Evaluate the compiled 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 inXPathConstants
, then anIllegalArgumentException
is thrown.If a
null
value is provided foritem
, an empty document will be used for the context. IfreturnType
isnull
, then aNullPointerException
is thrown.- Parameters:
item
- The starting context (node or node list, for example).returnType
- The desired return type.- Returns:
- The
Object
that is the result of evaluating the expression and converting the result toreturnType
. - Throws:
XPathExpressionException
- If the expression cannot be evaluated.IllegalArgumentException
- IfreturnType
is not one of the types defined inXPathConstants
.NullPointerException
- IfreturnType
isnull
.
-
evaluate
Evaluate the compiled XPath expression in the specified context and return the result as a
String
.This method calls
evaluate(Object item, QName returnType)
with areturnType
ofXPathConstants.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 foritem
, an empty document will be used for the context.- Parameters:
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 aString
. - Throws:
XPathExpressionException
- If the expression cannot be evaluated.
-
evaluate
Evaluate the compiled 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 callsevaluate(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 inXPathConstants
, then anIllegalArgumentException
is thrown.If
source
orreturnType
isnull
, then aNullPointerException
is thrown.- Parameters:
source
- TheInputSource
of the document to evaluate over.returnType
- The desired return type.- Returns:
- The
Object
that is the result of evaluating the expression and converting the result toreturnType
. - Throws:
XPathExpressionException
- If the expression cannot be evaluated.IllegalArgumentException
- IfreturnType
is not one of the types defined inXPathConstants
.NullPointerException
- Ifsource
orreturnType
isnull
.
-
evaluate
Evaluate the compiled XPath expression in the context of the specified
InputSource
and return the result as aString
.This method calls
evaluate(InputSource source, QName returnType)
with areturnType
ofXPathConstants.STRING
.See Evaluation of XPath Expressions for context item evaluation, variable, function and QName resolution and return type conversion.
If
source
isnull
, then aNullPointerException
is thrown.- Parameters:
source
- TheInputSource
of the document to evaluate over.- Returns:
- The
String
that is the result of evaluating the expression and converting the result to aString
. - Throws:
XPathExpressionException
- If the expression cannot be evaluated.NullPointerException
- Ifsource
isnull
.
-