javax.xml.xpath
Interface XPathExpression
public 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.
|
$Revision: 226183 $, $Date: 2005-04-08 12:39:14 +0200 (Fri, 08 Apr 2005) $ String | evaluate(Object item) - Evaluate the compiled XPath expression in the specified context and return the result as a
String .
|
Object | evaluate(Object item, QName returnType) - Evaluate the compiled XPath expression in the specified context and return the result as the specified type.
|
String | evaluate(InputSource source) - Evaluate the compiled XPath expression in the context of the specified
InputSource and return the result as a
String .
|
Object | evaluate(InputSource source, QName returnType) - Evaluate the compiled XPath expression in the context of the specified
InputSource and return the result as the
specified type.
|
evaluate
public String evaluate(Object item)
throws XPathExpressionException
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 a
returnType
of
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.
item
- The starting context (node or node list, for example).
- The
String
that is the result of evaluating the expression and converting the result to a
String
.
evaluate
public Object evaluate(Object item,
QName returnType)
throws XPathExpressionException
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 in
XPathConstants
,
then an
IllegalArgumentException
is thrown.
If a
null
value is provided for
item
, an empty document will be used for the
context.
If
returnType
is
null
, then a
NullPointerException
is thrown.
item
- The starting context (node or node list, for example).returnType
- The desired return type.
- The
Object
that is the result of evaluating the expression and converting the result to
returnType
.
evaluate
public String evaluate(InputSource source)
throws XPathExpressionException
Evaluate the compiled XPath expression in the context of the specified
InputSource
and return the result as a
String
.
This method calls
evaluate(InputSource source, QName returnType)
with a
returnType
of
XPathConstants.STRING
.
See
Evaluation of XPath Expressions for context item evaluation,
variable, function and QName resolution and return type conversion.
If
source
is
null
, then a
NullPointerException
is thrown.
source
- The InputSource
of the document to evaluate over.
- The
String
that is the result of evaluating the expression and converting the result to a
String
.
evaluate
public Object evaluate(InputSource source,
QName returnType)
throws XPathExpressionException
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 calls
evaluate(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
XPathConstants
,
then an
IllegalArgumentException
is thrown.
If
source
or
returnType
is
null
,
then a
NullPointerException
is thrown.
source
- The InputSource
of the document to evaluate over.returnType
- The desired return type.
- The
Object
that is the result of evaluating the expression and converting the result to
returnType
.