javax.xml.xpath
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 {@link XPathVariableResolver}.
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}.
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. |
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, Expressions
Method Summary | |
---|---|
Object | evaluate(Object item, QName returnType) 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 If a |
String | evaluate(Object item) Evaluate the compiled XPath expression in the specified context and return the result as a This method calls {@link #evaluate(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(InputSource source, QName returnType) Evaluate the compiled XPath expression in the context of the specified This method builds a data model for the {@link InputSource} and calls {@link #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 If |
String | evaluate(InputSource source) Evaluate the compiled XPath expression in the context of the specified This method calls {@link #evaluate(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 |
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 {@link 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.
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 to
returnType
.
Throws: XPathExpressionException If the expression cannot be evaluated. IllegalArgumentException If returnType
is not one of the types defined in {@link XPathConstants}. NullPointerException If returnType
is null
.
Evaluate the compiled XPath expression in the specified context and return the result as a String
.
This method calls {@link #evaluate(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.
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 a
String
.
Throws: XPathExpressionException If the expression cannot be evaluated.
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 {@link InputSource} and calls {@link #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 {@link XPathConstants},
then an IllegalArgumentException
is thrown.
If source
or returnType
is null
,
then a NullPointerException
is thrown.
Parameters: source The InputSource
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 to
returnType
.
Throws: XPathExpressionException If the expression cannot be evaluated. IllegalArgumentException If returnType
is not one of the types defined in {@link XPathConstants}. NullPointerException If source
or returnType
is null
.
Evaluate the compiled XPath expression in the context of the specified InputSource
and return the result as a
String
.
This method calls {@link #evaluate(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 source
is null
, then a NullPointerException
is thrown.
Parameters: 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 the expression cannot be evaluated. NullPointerException If source
is null
.