Interface XPathExpression
public interface XPathExpression
XPathExpression
provides access to compiled XPath expressions. The XPath evaluation is affected by the factors described in the following table.
Factor | Behavior |
---|---|
context | The type of the context is implementation-dependent. If the value is null, the operation must have no dependency on the context, otherwise an XPathExpressionException will be thrown. 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. |
An XPath expression is not thread-safe and not reentrant. In other words, it is the application's responsibility to make sure that one XPathExpression
object is not used from more than one thread at any given time, and while the evaluate
method is invoked, applications may not recursively call the evaluate
method.
- Since:
- 1.5
- See Also:
- XML Path Language (XPath) Version 1.0, Expressions
Method Summary
Modifier and Type | Method | Description |
---|---|---|
String | evaluate(Object item) | Evaluate the compiled XPath expression in the specified context and return the result as a |
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 |
Object | evaluate(InputSource source,
QName returnType) | Evaluate the compiled XPath expression in the context of the specified |
default XPathEvaluationResult<?> | evaluateExpression(Object item) | Evaluate the compiled XPath expression in the specified context. |
default <T> T | evaluateExpression(Object item,
Class<T> type) | Evaluate the compiled XPath expression in the specified context, and return the result with the type specified through the |
default XPathEvaluationResult<?> | evaluateExpression(InputSource source) | Evaluate the compiled XPath expression in the specified context. |
default <T> T | evaluateExpression(InputSource source,
Class<T> type) | Evaluate the compiled XPath expression in the specified context, and return the result with the type specified through the |
Method Detail
evaluate
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.
The parameter item
represents the context the XPath expression will be operated on. The type of the context is implementation-dependent. If the value is null
, the operation must have no dependency on the context, otherwise an XPathExpressionException will be thrown.
- Implementation Note:
- The type of the context is usually
Node
. - Parameters:
-
item
- The context the XPath expression will be evaluated in. -
returnType
- The result type expected to be returned by the XPath expression. - 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
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.
The parameter item
represents the context the XPath expression will be operated on. The type of the context is implementation-dependent. If the value is null
, the operation must have no dependency on the context, otherwise an XPathExpressionException will be thrown.
- Implementation Note:
- The type of the context is usually
Node
. - Parameters:
-
item
- The context the XPath expression will be evaluated in. - Returns:
- The result of evaluating an XPath expression as a
String
. - Throws:
-
XPathExpressionException
- If the expression cannot be evaluated.
evaluate
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.
- 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 or returnType
isnull
.
evaluate
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.
- 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
.
evaluateExpression
default <T> T evaluateExpression(Object item, Class<T> type) throws XPathExpressionException
Evaluate the compiled XPath expression in the specified context, and return the result with the type specified through the class type
.
The parameter item
represents the context the XPath expression will be operated on. The type of the context is implementation-dependent. If the value is null
, the operation must have no dependency on the context, otherwise an XPathExpressionException will be thrown.
- Implementation Requirements:
- The default implementation in the XPath API is equivalent to:
(T)evaluate(item, XPathEvaluationResult.XPathResultType.getQNameType(type));
Since theevaluate
method does not support theANY
type, specifying XPathEvaluationResult as the type will result in IllegalArgumentException. Any implementation supporting theANY
type must override this method. - Implementation Note:
- The type of the context is usually
Node
. - Type Parameters:
-
T
- The class type that will be returned by the XPath expression. - Parameters:
-
item
- The context the XPath expression will be evaluated in. -
type
- The class type expected to be returned by the XPath expression. - Returns:
- The result of evaluating the expression.
- Throws:
-
XPathExpressionException
- If the expression cannot be evaluated. -
IllegalArgumentException
- Iftype
is not of the types corresponding to the types defined in theXPathResultType
, or XPathEvaluationResult is specified as the type but an implementation supporting theANY
type is not available. -
NullPointerException
- Iftype
isnull
. - Since:
- 9
evaluateExpression
default XPathEvaluationResult<?> evaluateExpression(Object item) throws XPathExpressionException
Evaluate the compiled XPath expression in the specified context. This is equivalent to calling evaluateExpression(Object item, Class type)
with type XPathEvaluationResult
:
evaluateExpression(item, XPathEvaluationResult.class);
The parameter item
represents the context the XPath expression will be operated on. The type of the context is implementation-dependent. If the value is null
, the operation must have no dependency on the context, otherwise an XPathExpressionException will be thrown.
- Implementation Requirements:
- The default implementation in the XPath API is equivalent to:
evaluateExpression(item, XPathEvaluationResult.class);
Since theevaluate
method does not support theANY
type, the default implementation of this method will always throw an IllegalArgumentException. Any implementation supporting theANY
type must therefore override this method. - Implementation Note:
- The type of the context is usually
Node
. - Parameters:
-
item
- The context the XPath expression will be evaluated in. - Returns:
- The result of evaluating the expression.
- Throws:
-
XPathExpressionException
- If the expression cannot be evaluated. -
IllegalArgumentException
- If the implementation of this method does not support theANY
type. - Since:
- 9
evaluateExpression
default <T> T evaluateExpression(InputSource source, Class<T> type) throws XPathExpressionException
Evaluate the compiled XPath expression in the specified context, and return the result with the type specified through the class type
This method builds a data model for the InputSource
and calls evaluateExpression(Object item, Class type)
on the resulting document object.
By default, the JDK's data model is Document
.
- Implementation Requirements:
- The default implementation in the XPath API is equivalent to:
(T)evaluate(source, XPathEvaluationResult.XPathResultType.getQNameType(type));
Since theevaluate
method does not support theANY
type, specifying XPathEvaluationResult as the type will result in IllegalArgumentException. Any implementation supporting theANY
type must override this method. - Type Parameters:
-
T
- The class type that will be returned by the XPath expression. - Parameters:
-
source
- TheInputSource
of the document to evaluate over. -
type
- The class type expected to be returned by the XPath expression. - Returns:
- The result of evaluating the expression.
- Throws:
-
XPathExpressionException
- If the expression cannot be evaluated. -
IllegalArgumentException
- Iftype
is not of the types corresponding to the types defined in theXPathResultType
, or XPathEvaluationResult is specified as the type but an implementation supporting theANY
type is not available. -
NullPointerException
- Ifsource or type
isnull
. - Since:
- 9
evaluateExpression
default XPathEvaluationResult<?> evaluateExpression(InputSource source) throws XPathExpressionException
Evaluate the compiled XPath expression in the specified context. This is equivalent to calling evaluateExpression(InputSource source, Class type)
with type XPathEvaluationResult
:
evaluateExpression(source, XPathEvaluationResult.class);
- Implementation Requirements:
- The default implementation in the XPath API is equivalent to:
(XPathEvaluationResult)evaluateExpression(source, XPathEvaluationResult.class);
Since theevaluate
method does not support theANY
type, the default implementation of this method will always throw an IllegalArgumentException. Any implementation supporting theANY
type must therefore override this method. - Parameters:
-
source
- TheInputSource
of the document to evaluate over. - Returns:
- The result of evaluating the expression.
- Throws:
-
XPathExpressionException
- If the expression cannot be evaluated. -
IllegalArgumentException
- If the implementation of this method does not support theANY
type. -
NullPointerException
- Ifsource
isnull
. - Since:
- 9