Package net.sf.saxon.xpath
Class XPathEvaluator
- java.lang.Object
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- net.sf.saxon.xpath.XPathEvaluator
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- All Implemented Interfaces:
javax.xml.xpath.XPath
public class XPathEvaluator extends java.lang.Object implements javax.xml.xpath.XPath
XPathEvaluator provides a simple API for standalone XPath processing (that is, executing XPath expressions in the absence of an XSLT stylesheet). It is an implementation of the JAXP 1.3 XPath interface, with additional methods provided (a) for backwards compatibility (b) to give extra control over the XPath evaluation, and (c) to support XPath 2.0.
- Author:
- Michael H. Kay
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Constructor Summary
Constructors Constructor Description XPathEvaluator()
Default constructor.XPathEvaluator(javax.xml.transform.Source source)
Construct an XPathEvaluator to process a particular source document.XPathEvaluator(Configuration config)
Construct an XPathEvaluator with a specified configuration.
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Method Summary
All Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method Description javax.xml.xpath.XPathExpression
compile(java.lang.String expr)
Compile an XPath 2.0 expressionXPathExpressionImpl
createExpression(java.lang.String expression)
Prepare an XPath expression for subsequent evaluation.java.util.List
evaluate(java.lang.String expression)
Prepare and execute an XPath expression, supplied as a string, and returning the results as a List.java.lang.String
evaluate(java.lang.String expr, java.lang.Object node)
Single-shot method to compile an execute an XPath 2.0 expression, returning the result as a string.java.lang.Object
evaluate(java.lang.String expr, java.lang.Object node, javax.xml.namespace.QName qName)
Single-shot method to compile and execute an XPath 2.0 expression.java.lang.String
evaluate(java.lang.String expr, org.xml.sax.InputSource inputSource)
Single-shot method to parse and build a source document, and compile an execute an XPath 2.0 expression, against that document, returning the result as a stringjava.lang.Object
evaluate(java.lang.String expr, org.xml.sax.InputSource inputSource, javax.xml.namespace.QName qName)
Single-shot method to parse and build a source document, and compile an execute an XPath 2.0 expression, against that documentjava.lang.Object
evaluateSingle(java.lang.String expression)
Prepare and execute an XPath expression, supplied as a string, and returning the first item in the result.javax.xml.namespace.NamespaceContext
getNamespaceContext()
Get the namespace context, if one has been set usingsetNamespaceContext(javax.xml.namespace.NamespaceContext)
StandaloneContext
getStaticContext()
Get the current static contextjavax.xml.xpath.XPathFunctionResolver
getXPathFunctionResolver()
Get the resolver for XPath functionsjavax.xml.xpath.XPathVariableResolver
getXPathVariableResolver()
Get the resolver for XPath variablesvoid
importSchema(javax.xml.transform.Source source)
Import a schema.boolean
isBackwardsCompatible()
Get the value of XPath 1.0 compatibility modestatic void
main(java.lang.String[] args)
A simple command-line interface for the XPathEvaluator (not documented).void
reset()
void
setBackwardsCompatible(boolean compatible)
Set XPath 1.0 compatibility mode on or off (by default, it is false)void
setContextNode(NodeInfo node)
Set the context node.void
setNamespaceContext(javax.xml.namespace.NamespaceContext namespaceContext)
Set the namespace context to be used.NodeInfo
setSource(javax.xml.transform.Source source)
Supply the document against which XPath expressions are to be executed.void
setStaticContext(StandaloneContext context)
Set the static context for compiling XPath expressions.void
setStripSpace(boolean strip)
Indicate whether all whitespace text nodes in the source document are to be removed.void
setXPathFunctionResolver(javax.xml.xpath.XPathFunctionResolver xPathFunctionResolver)
Set the resolver for XPath functionsvoid
setXPathVariableResolver(javax.xml.xpath.XPathVariableResolver xPathVariableResolver)
Set the resolver for XPath variables
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Constructor Detail
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XPathEvaluator
public XPathEvaluator()
Default constructor. Creates an XPathEvaluator with a default configuration and name pool. The default Configuration is not schema-aware.
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XPathEvaluator
public XPathEvaluator(Configuration config)
Construct an XPathEvaluator with a specified configuration.- Parameters:
config
- the configuration to be used. If schema-aware XPath expressions are to be used, this must be a SchemaAwareConfiguration.
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XPathEvaluator
public XPathEvaluator(javax.xml.transform.Source source) throws XPathException
Construct an XPathEvaluator to process a particular source document. This is equivalent to using the default constructor and immediately calling setSource().- Parameters:
source
- The source document (or a specific node within it).- Throws:
XPathException
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Method Detail
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setStripSpace
public void setStripSpace(boolean strip)
Indicate whether all whitespace text nodes in the source document are to be removed. This option has no effect unless it is called before the call on setSource(), and unless the Source supplied to setSource() is a SAXSource or StreamSource.- Parameters:
strip
- True if all whitespace text nodes are to be stripped from the source document, false otherwise. The default if the method is not called is false.
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setSource
public NodeInfo setSource(javax.xml.transform.Source source) throws XPathException
Supply the document against which XPath expressions are to be executed. This method must be called before preparing or executing an XPath expression. Setting a new source document clears all the namespaces that have been declared.- Parameters:
source
- Any javax.xml.transform.Source object representing the document against which XPath expressions will be executed. Note that a SaxonDocumentInfo
(indeed anyNodeInfo
) can be used as a Source. To use a third-party DOM Document as a source, create an instance ofDOMSource
to wrap it.The Source object supplied also determines the initial setting of the context item. In most cases the context node will be the root of the supplied document; however, if a NodeInfo or DOMSource is supplied it can be any node in the document.
- Returns:
- the NodeInfo of the start node in the resulting document object.
- Throws:
XPathException
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setStaticContext
public void setStaticContext(StandaloneContext context)
Set the static context for compiling XPath expressions. This provides control over the environment in which the expression is compiled, for example it allows namespace prefixes to be declared, variables to be bound and functions to be defined. For most purposes, the static context can be defined by providing and tailoring an instance of the StandaloneContext class. Until this method is called, a default static context is used, in which no namespaces are defined other than the standard ones (xml, xslt, and saxon), and no variables or functions (other than the core XPath functions) are available.
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getStaticContext
public StandaloneContext getStaticContext()
Get the current static context
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createExpression
public XPathExpressionImpl createExpression(java.lang.String expression) throws XPathException
Prepare an XPath expression for subsequent evaluation.- Parameters:
expression
- The XPath expression to be evaluated, supplied as a string.- Returns:
- an XPathExpression object representing the prepared expression
- Throws:
XPathException
- if the syntax of the expression is wrong, or if it references namespaces, variables, or functions that have not been declared.
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setContextNode
public void setContextNode(NodeInfo node)
Set the context node. This provides the context node for any expressions executed after this method is called, including expressions that were prepared before it was called.- Parameters:
node
- The node to be used as the context node. This must be a node within the context document (the document supplied using the setSource() method).- Throws:
java.lang.NullPointerException
- if the argument is nulljava.lang.IllegalArgumentException
- if the supplied node is not a node in the context document
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evaluate
public java.util.List evaluate(java.lang.String expression) throws XPathException
Prepare and execute an XPath expression, supplied as a string, and returning the results as a List.- Parameters:
expression
- The XPath expression to be evaluated, supplied as a string.- Returns:
- The results of the expression, as a List. The List represents the sequence
of items returned by the expression. Each item in the list will either be an object
representing a node, or a Java object representing an atomic value.
The types of Java object that may be included in the list, and the XML Schema data types that they
correspond to, are as follows:
- Boolean (xs:boolean)
- String (xs:string)
- BigDecimal (xs:decimal)
- Long (xs:integer and its derived types)
- Double (xs:double)
- Float (xs:float)
- Date (xs:date, xs:dateTime)
- Throws:
XPathException
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reset
public void reset()
- Specified by:
reset
in interfacejavax.xml.xpath.XPath
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setBackwardsCompatible
public void setBackwardsCompatible(boolean compatible)
Set XPath 1.0 compatibility mode on or off (by default, it is false)- Parameters:
compatible
- true if XPath 1.0 compatibility mode is to be set to true, false if it is to be set to false.
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isBackwardsCompatible
public boolean isBackwardsCompatible()
Get the value of XPath 1.0 compatibility mode- Returns:
- true if XPath 1.0 compatibility mode is set
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setXPathVariableResolver
public void setXPathVariableResolver(javax.xml.xpath.XPathVariableResolver xPathVariableResolver)
Set the resolver for XPath variables- Specified by:
setXPathVariableResolver
in interfacejavax.xml.xpath.XPath
- Parameters:
xPathVariableResolver
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getXPathVariableResolver
public javax.xml.xpath.XPathVariableResolver getXPathVariableResolver()
Get the resolver for XPath variables- Specified by:
getXPathVariableResolver
in interfacejavax.xml.xpath.XPath
- Returns:
- the resolver, if one has been set
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setXPathFunctionResolver
public void setXPathFunctionResolver(javax.xml.xpath.XPathFunctionResolver xPathFunctionResolver)
Set the resolver for XPath functions- Specified by:
setXPathFunctionResolver
in interfacejavax.xml.xpath.XPath
- Parameters:
xPathFunctionResolver
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getXPathFunctionResolver
public javax.xml.xpath.XPathFunctionResolver getXPathFunctionResolver()
Get the resolver for XPath functions- Specified by:
getXPathFunctionResolver
in interfacejavax.xml.xpath.XPath
- Returns:
- the resolver, if one has been set
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setNamespaceContext
public void setNamespaceContext(javax.xml.namespace.NamespaceContext namespaceContext)
Set the namespace context to be used. This supplements any namespaces declared directly using declareNamespace on the staticContext object- Specified by:
setNamespaceContext
in interfacejavax.xml.xpath.XPath
- Parameters:
namespaceContext
- The namespace context
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getNamespaceContext
public javax.xml.namespace.NamespaceContext getNamespaceContext()
Get the namespace context, if one has been set usingsetNamespaceContext(javax.xml.namespace.NamespaceContext)
- Specified by:
getNamespaceContext
in interfacejavax.xml.xpath.XPath
- Returns:
- the namespace context if set, or null otherwise
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importSchema
public void importSchema(javax.xml.transform.Source source) throws SchemaException
Import a schema. This is possible only if the schema-aware version of Saxon is being used, and if the Configuration is a SchemaAwareConfiguration. Having imported a schema, the types defined in that schema become part of the static context.- Parameters:
source
- A Source object identifying the schema document to be loaded- Throws:
SchemaException
- if the schema contained in this document is invalidjava.lang.UnsupportedOperationException
- if the configuration is not schema-aware
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compile
public javax.xml.xpath.XPathExpression compile(java.lang.String expr) throws javax.xml.xpath.XPathExpressionException
Compile an XPath 2.0 expression- Specified by:
compile
in interfacejavax.xml.xpath.XPath
- Parameters:
expr
- the XPath 2.0 expression to be compiled, as a string- Returns:
- the compiled form of the expression
- Throws:
javax.xml.xpath.XPathExpressionException
- if there are any static errors in the expression. Note that references to undeclared variables are not treated as static errors, because variables are not pre-declared using this API.
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evaluate
public java.lang.Object evaluate(java.lang.String expr, java.lang.Object node, javax.xml.namespace.QName qName) throws javax.xml.xpath.XPathExpressionException
Single-shot method to compile and execute an XPath 2.0 expression.- Specified by:
evaluate
in interfacejavax.xml.xpath.XPath
- Parameters:
expr
- The XPath 2.0 expression to be compiled and executednode
- The context node for evaluation of the expressionqName
- The type of result required. For details, seeXPathExpressionImpl.evaluate(Object, javax.xml.namespace.QName)
- Returns:
- the result of evaluating the expression, returned as described in
XPathExpressionImpl.evaluate(Object, javax.xml.namespace.QName)
- Throws:
javax.xml.xpath.XPathExpressionException
- if any static or dynamic error occurs in evaluating the expression.
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evaluate
public java.lang.String evaluate(java.lang.String expr, java.lang.Object node) throws javax.xml.xpath.XPathExpressionException
Single-shot method to compile an execute an XPath 2.0 expression, returning the result as a string.- Specified by:
evaluate
in interfacejavax.xml.xpath.XPath
- Parameters:
expr
- The XPath 2.0 expression to be compiled and executednode
- The context node for evaluation of the expression- Returns:
- the result of evaluating the expression, converted to a string as if by calling the XPath string() function
- Throws:
javax.xml.xpath.XPathExpressionException
- if any static or dynamic error occurs in evaluating the expression.
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evaluate
public java.lang.Object evaluate(java.lang.String expr, org.xml.sax.InputSource inputSource, javax.xml.namespace.QName qName) throws javax.xml.xpath.XPathExpressionException
Single-shot method to parse and build a source document, and compile an execute an XPath 2.0 expression, against that document- Specified by:
evaluate
in interfacejavax.xml.xpath.XPath
- Parameters:
expr
- The XPath 2.0 expression to be compiled and executedinputSource
- The source document: this will be parsed and built into a tree, and the XPath expression will be executed with the root node of the tree as the context nodeqName
- The type of result required. For details, seeXPathExpressionImpl.evaluate(Object, javax.xml.namespace.QName)
- Returns:
- the result of evaluating the expression, returned as described in
XPathExpressionImpl.evaluate(Object, javax.xml.namespace.QName)
- Throws:
javax.xml.xpath.XPathExpressionException
- if any static or dynamic error occurs in evaluating the expression.
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evaluate
public java.lang.String evaluate(java.lang.String expr, org.xml.sax.InputSource inputSource) throws javax.xml.xpath.XPathExpressionException
Single-shot method to parse and build a source document, and compile an execute an XPath 2.0 expression, against that document, returning the result as a string- Specified by:
evaluate
in interfacejavax.xml.xpath.XPath
- Parameters:
expr
- The XPath 2.0 expression to be compiled and executedinputSource
- The source document: this will be parsed and built into a tree, and the XPath expression will be executed with the root node of the tree as the context node- Returns:
- the result of evaluating the expression, converted to a string as if by calling the XPath string() function
- Throws:
javax.xml.xpath.XPathExpressionException
- if any static or dynamic error occurs in evaluating the expression.
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evaluateSingle
public java.lang.Object evaluateSingle(java.lang.String expression) throws XPathException
Prepare and execute an XPath expression, supplied as a string, and returning the first item in the result. This is useful where it is known that the expression will only return a singleton value (for example, a single node, or a boolean).- Parameters:
expression
- The XPath expression to be evaluated, supplied as a string.- Returns:
- The first item in the sequence returned by the expression. If the expression returns an empty sequence, this method returns null. Otherwise, it returns the first item in the result sequence, represented as a Java object using the same mapping as for the evaluate() method
- Throws:
XPathException
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main
public static void main(java.lang.String[] args) throws java.lang.Exception
A simple command-line interface for the XPathEvaluator (not documented). First parameter is the filename containing the source document, second parameter is the XPath expression.- Throws:
java.lang.Exception
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