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.XPathXPathEvaluator implements the JAXP 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 later XPath versions (2.0, 3.0, 3.1).
The JAXP API is designed at one level to be object-model independent, but in other respects (especially in Java SE 9) it is designed specifically with DOM in mind. The Saxon implementation makes its own decisions about how to handle non-DOM nodes. Specifically, when an expression with return type
XPathConstants.NODEis evaluated, Saxon returns the underlying node from the native object model; when the return type is given asXPathConstants.NODESET, the nodes are delivered as a DOMNodeListif they are DOM nodes, or as aListotherwise.For an alternative XPath API, offering more complete access to Saxon capabilities, see
XPathCompiler.Note that the
XPathEvaluatorlinks to a SaxonConfigurationobject. By default a newConfigurationis created automatically. In many applications, however, it is desirable to share a configuration. The default configuration is not schema aware. All source documents used by XPath expressions under this evaluator must themselves be built using theConfigurationused by this evaluator.
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Constructor Summary
Constructors Constructor Description XPathEvaluator()Default constructor.XPathEvaluator(Configuration config)Construct an XPathEvaluator with a specified configuration.
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description javax.xml.xpath.XPathExpressioncompile(java.lang.String expr)Compile an XPath 3.1 expressionjava.lang.Stringevaluate(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.Objectevaluate(java.lang.String expr, java.lang.Object node, javax.xml.namespace.QName qName)Single-shot method to compile and execute an XPath 3.1 expression.java.lang.Stringevaluate(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.Objectevaluate(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 documentConfigurationgetConfiguration()Get the Configuration used by this XPathEvaluatorjavax.xml.namespace.NamespaceContextgetNamespaceContext()Get the namespace context, if one has been set usingsetNamespaceContext(javax.xml.namespace.NamespaceContext)JAXPXPathStaticContextgetStaticContext()Get the current static context.javax.xml.xpath.XPathFunctionResolvergetXPathFunctionResolver()Get the resolver for XPath functionsjavax.xml.xpath.XPathVariableResolvergetXPathVariableResolver()Get the resolver for XPath variablesvoidimportSchema(javax.xml.transform.Source source)Import a schema.voidreset()voidsetNamespaceContext(javax.xml.namespace.NamespaceContext namespaceContext)Set the namespace context to be used.voidsetXPathFunctionResolver(javax.xml.xpath.XPathFunctionResolver xPathFunctionResolver)Set the resolver for XPath functionsvoidsetXPathVariableResolver(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 Configuration appropriate to the version of the Saxon software being run.
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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 an EnterpriseConfiguration.
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Method Detail
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getConfiguration
public Configuration getConfiguration()
Get the Configuration used by this XPathEvaluator- Returns:
- the Configuration used by this XPathEvaluator
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getStaticContext
public JAXPXPathStaticContext getStaticContext()
Get the current static context. The caller can set properties of the returned static context to influence the way in which XPath expressions are compiled and evaluated; for example it is possible to set whether XPath 1.0 backwards compatibility is enabled or not.- Returns:
- the static context
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reset
public void reset()
- Specified by:
resetin interfacejavax.xml.xpath.XPath
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setXPathVariableResolver
public void setXPathVariableResolver(javax.xml.xpath.XPathVariableResolver xPathVariableResolver)
Set the resolver for XPath variables- Specified by:
setXPathVariableResolverin interfacejavax.xml.xpath.XPath- Parameters:
xPathVariableResolver- a resolver for variables
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getXPathVariableResolver
public javax.xml.xpath.XPathVariableResolver getXPathVariableResolver()
Get the resolver for XPath variables- Specified by:
getXPathVariableResolverin 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:
setXPathFunctionResolverin interfacejavax.xml.xpath.XPath- Parameters:
xPathFunctionResolver- a resolver for XPath function calls
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getXPathFunctionResolver
public javax.xml.xpath.XPathFunctionResolver getXPathFunctionResolver()
Get the resolver for XPath functions- Specified by:
getXPathFunctionResolverin 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.- Specified by:
setNamespaceContextin 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:
getNamespaceContextin 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 SchemaExceptionImport a schema. This is possible only if Saxon-EE is being used, and if the Configuration is an EnterpriseConfiguration. 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.XPathExpressionExceptionCompile an XPath 3.1 expression- Specified by:
compilein interfacejavax.xml.xpath.XPath- Parameters:
expr- the XPath 3.1 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.XPathExpressionExceptionSingle-shot method to compile and execute an XPath 3.1 expression.- Specified by:
evaluatein interfacejavax.xml.xpath.XPath- Parameters:
expr- The XPath 3.1 expression to be compiled and executednode- The context node for evaluation of the expression.This may be a NodeInfo object, representing a node in Saxon's native implementation of the data model, or it may be a node in any supported external object model: DOM, JDOM, DOM4J, or XOM, or any other model for which support has been configured in the Configuration. Note that the supporting libraries for the chosen model must be on the class path.
Contrary to the interface specification, Saxon does not supply an empty document when the value is null. This is because XPath 2.0 allows the context item to be "absent" (null). So Saxon executes the XPath expression with the context item undefined.
qName- 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.XPathExpressionExceptionSingle-shot method to compile an execute an XPath 2.0 expression, returning the result as a string.- Specified by:
evaluatein interfacejavax.xml.xpath.XPath- Parameters:
expr- The XPath 2.0 expression to be compiled and executednode- The context node for evaluation of the expressionThis may be a NodeInfo object, representing a node in Saxon's native implementation of the data model, or it may be a node in any supported external object model: DOM, JDOM, DOM4J, or XOM, or any other model for which support has been configured in the Configuration. Note that the supporting libraries for the chosen model must be on the class path.
Contrary to the interface specification, Saxon does not supply an empty document when the value is null. This is because XPath 2.0 allows the context item to be "absent" (null). So Saxon executes the XPath expression with the context item undefined.
- 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.XPathExpressionExceptionSingle-shot method to parse and build a source document, and compile an execute an XPath 2.0 expression, against that document- Specified by:
evaluatein 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.qName- 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.java.lang.NullPointerException- if any of the three arguments is null
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evaluate
public java.lang.String evaluate(java.lang.String expr, org.xml.sax.InputSource inputSource) throws javax.xml.xpath.XPathExpressionExceptionSingle-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:
evaluatein 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.java.lang.NullPointerException- if either of the two arguments is null
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