Package org.apache.xpath.domapi
Class XPathEvaluatorImpl
java.lang.Object
org.apache.xpath.domapi.XPathEvaluatorImpl
- All Implemented Interfaces:
org.w3c.dom.xpath.XPathEvaluator
The class provides an implementation of XPathEvaluator according
to the DOM L3 XPath Specification, Working Group Note 26 February 2004.
See also the Document Object Model (DOM) Level 3 XPath Specification.
The evaluation of XPath expressions is provided byXPathEvaluator
, which will provide evaluation of XPath 1.0
expressions with no specialized extension functions or variables. It is
expected that the XPathEvaluator
interface will be
implemented on the same object which implements the Document
interface in an implementation which supports the XPath DOM module.
XPathEvaluator
implementations may be available from other
sources that may provide support for special extension functions or
variables which are not defined in this specification.- See Also:
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XPathEvaluator
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Constructor Summary
ConstructorsConstructorDescriptionConstructor in the case that the XPath expression can be evaluated without needing an XML document at all.Constructor for XPathEvaluatorImpl. -
Method Summary
Modifier and TypeMethodDescriptionorg.w3c.dom.xpath.XPathExpression
createExpression
(String expression, org.w3c.dom.xpath.XPathNSResolver resolver) Creates a parsed XPath expression with resolved namespaces.org.w3c.dom.xpath.XPathNSResolver
createNSResolver
(Node nodeResolver) Adapts any DOM node to resolve namespaces so that an XPath expression can be easily evaluated relative to the context of the node where it appeared within the document.evaluate
(String expression, Node contextNode, org.w3c.dom.xpath.XPathNSResolver resolver, short type, Object result) Evaluates an XPath expression string and returns a result of the specified type if possible.
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Constructor Details
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XPathEvaluatorImpl
Constructor for XPathEvaluatorImpl.- Parameters:
doc
- The document to be searched, to parallel the case where'' the XPathEvaluator is obtained by casting the document.
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XPathEvaluatorImpl
public XPathEvaluatorImpl()Constructor in the case that the XPath expression can be evaluated without needing an XML document at all.
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Method Details
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createExpression
public org.w3c.dom.xpath.XPathExpression createExpression(String expression, org.w3c.dom.xpath.XPathNSResolver resolver) throws org.w3c.dom.xpath.XPathException, DOMException Creates a parsed XPath expression with resolved namespaces. This is useful when an expression will be reused in an application since it makes it possible to compile the expression string into a more efficient internal form and preresolve all namespace prefixes which occur within the expression.- Specified by:
createExpression
in interfaceorg.w3c.dom.xpath.XPathEvaluator
- Parameters:
expression
- The XPath expression string to be parsed.resolver
- Theresolver
permits translation of prefixes within the XPath expression into appropriate namespace URIs . If this is specified asnull
, any namespace prefix within the expression will result inDOMException
being thrown with the codeNAMESPACE_ERR
.- Returns:
- The compiled form of the XPath expression.
- Throws:
org.w3c.dom.xpath.XPathException
- INVALID_EXPRESSION_ERR: Raised if the expression is not legal according to the rules of theXPathEvaluator
iDOMException
- NAMESPACE_ERR: Raised if the expression contains namespace prefixes which cannot be resolved by the specifiedXPathNSResolver
.- See Also:
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XPathEvaluator.createExpression(String, XPathNSResolver)
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createNSResolver
Adapts any DOM node to resolve namespaces so that an XPath expression can be easily evaluated relative to the context of the node where it appeared within the document. This adapter works like the DOM Level 3 methodlookupNamespaceURI
on nodes in resolving the namespaceURI from a given prefix using the current information available in the node's hierarchy at the time lookupNamespaceURI is called, also correctly resolving the implicit xml prefix.- Specified by:
createNSResolver
in interfaceorg.w3c.dom.xpath.XPathEvaluator
- Parameters:
nodeResolver
- The node to be used as a context for namespace resolution.- Returns:
XPathNSResolver
which resolves namespaces with respect to the definitions in scope for a specified node.- See Also:
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XPathEvaluator.createNSResolver(Node)
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evaluate
public Object evaluate(String expression, Node contextNode, org.w3c.dom.xpath.XPathNSResolver resolver, short type, Object result) throws org.w3c.dom.xpath.XPathException, DOMException Evaluates an XPath expression string and returns a result of the specified type if possible.- Specified by:
evaluate
in interfaceorg.w3c.dom.xpath.XPathEvaluator
- Parameters:
expression
- The XPath expression string to be parsed and evaluated.contextNode
- Thecontext
is context node for the evaluation of this XPath expression. If the XPathEvaluator was obtained by casting theDocument
then this must be owned by the same document and must be aDocument
,Element
,Attribute
,Text
,CDATASection
,Comment
,ProcessingInstruction
, orXPathNamespace
node. If the context node is aText
or aCDATASection
, then the context is interpreted as the whole logical text node as seen by XPath, unless the node is empty in which case it may not serve as the XPath context.resolver
- Theresolver
permits translation of prefixes within the XPath expression into appropriate namespace URIs . If this is specified asnull
, any namespace prefix within the expression will result inDOMException
being thrown with the codeNAMESPACE_ERR
.type
- If a specifictype
is specified, then the result will be coerced to return the specified type relying on XPath type conversions and fail if the desired coercion is not possible. This must be one of the type codes ofXPathResult
.result
- Theresult
specifies a specific result object which may be reused and returned by this method. If this is specified asnull
or the implementation does not reuse the specified result, a new result object will be constructed and returned.For XPath 1.0 results, this object will be of typeXPathResult
.- Returns:
- The result of the evaluation of the XPath expression.For XPath
1.0 results, this object will be of type
XPathResult
. - Throws:
org.w3c.dom.xpath.XPathException
- INVALID_EXPRESSION_ERR: Raised if the expression is not legal according to the rules of theXPathEvaluator
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TYPE_ERR: Raised if the result cannot be converted to return the specified type.DOMException
- NAMESPACE_ERR: Raised if the expression contains namespace prefixes which cannot be resolved by the specifiedXPathNSResolver
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WRONG_DOCUMENT_ERR: The Node is from a document that is not supported by this XPathEvaluator.
NOT_SUPPORTED_ERR: The Node is not a type permitted as an XPath context node.- See Also:
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XPathEvaluator.evaluate(String, Node, XPathNSResolver, short, XPathResult)
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