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SUMMARY: INNER | FIELD | CONSTR | METHOD | DETAIL: FIELD | CONSTR | METHOD |
Defines the interface to an object which represents an XPath 1.0 expression which can be evaluated against a variety of different XML object models.
Most of the evaluation methods take a context object. This is typically a node or node set object (which is typically a List of node objects) or a Jaxen Context object. A null context is allowed, meaning that there is no XML nodes on which to evaluate.
XPath for dom4j
,
XPath for JDOM
,
XPath for W3C DOM
,
XPath for Electric XML
Method Summary | |
void |
addNamespace(String prefix,
String uri)
Add a namespace prefix-to-URI mapping for this XPath expression. |
boolean |
booleanValueOf(Object context)
Retrieve a boolean-value interpretation of this XPath expression when evaluated against a given context. |
Object |
evaluate(Object context)
Evaluate this XPath against a given context. |
FunctionContext |
getFunctionContext()
Retrieve the FunctionContext used by this XPath
expression. |
NamespaceContext |
getNamespaceContext()
Retrieve the NamespaceContext used by this XPath
expression. |
Navigator |
getNavigator()
Retrieve the XML object-model-specific Navigator
for us in evaluating this XPath expression. |
VariableContext |
getVariableContext()
Retrieve the VariableContext used by this XPath
expression. |
Number |
numberValueOf(Object context)
Retrieve a number-value interpretation of this XPath expression when evaluated against a given context. |
List |
selectNodes(Object context)
Select all nodes that are selectable by this XPath expression. |
Object |
selectSingleNode(Object context)
Select only the first node that is selectable by this XPath expression. |
void |
setFunctionContext(FunctionContext functionContext)
Set a FunctionContext for use with this XPath
expression. |
void |
setNamespaceContext(NamespaceContext namespaceContext)
Set a NamespaceContext for use with this
XPath expression. |
void |
setVariableContext(VariableContext variableContext)
Set a VariableContext for use with this XPath
expression. |
String |
stringValueOf(Object context)
Retrieve a string-value interpretation of this XPath expression when evaluated against a given context. |
String |
valueOf(Object context)
Deprecated. As of Jaxen 1.0 RC1 please use instead |
Method Detail |
public Object evaluate(Object context) throws JaxenException
The context of evaluation my be a document, an element, or a set of elements.
If the expression evaluates to a single primitive
(String, Number or Boolean) type, it is returned
directly. Otherwise, the returned value is a
List (a node-set
, in the terms of the
specification) of values.
When using this method, one must be careful to
test the class of the returned objects, and of
each of the composite members if a List
is returned. If the returned members are XML entities,
they will be the actual Document
,
Element
or Attribute
objects
as defined by the concrete XML object-model implementation,
directly from the context document. This does not
return copies of anything, but merely returns
references to entities within the source document.
The
- node, nodeset or Context object for evaluation. This value can be nullpublic List selectNodes(Object context) throws JaxenException
NOTE: In most cases, nodes will be returned
in document-order, as defined by the XML Canonicalization
specification. The exception occurs when using XPath
expressions involving the union
operator
(denoted with the pipe '|' character).
The
- node, nodeset or Context object for evaluation. This value can be nullnode-set
of all items selected
by this XPath expression.selectSingleNode(java.lang.Object)
public Object selectSingleNode(Object context) throws JaxenException
union
operator
(denoted with the pipe '|' character).
The
- node, nodeset or Context object for evaluation. This value can be nullnode-set
of all items selected
by this XPath expression.selectNodes(java.lang.Object)
public String valueOf(Object context) throws JaxenException
instead
The string-value of the expression is determined per
the string(..)
core function as defined
in the XPath specification. This means that an expression
that selects more than one nodes will return the string value
of the first node in the node set..
The
- node, nodeset or Context object for evaluation. This value can be nullpublic String stringValueOf(Object context) throws JaxenException
The string-value of the expression is determined per
the string(..)
core function as defined
in the XPath specification. This means that an expression
that selects more than one nodes will return the string value
of the first node in the node set..
The
- node, nodeset or Context object for evaluation. This value can be nullpublic boolean booleanValueOf(Object context) throws JaxenException
The boolean-value of the expression is determined per
the boolean(..)
core function as defined
in the XPath specification. This means that an expression
that selects zero nodes will return false
,
while an expression that selects one-or-more nodes will
return true
.
The
- node, nodeset or Context object for evaluation. This value can be nullpublic Number numberValueOf(Object context) throws JaxenException
The number-value of the expression is determined per
the number(..)
core function as defined
in the XPath specification. This means that if this
expression selects multiple nodes, the number-value
of the first node is returned.
The
- node, nodeset or Context object for evaluation. This value can be nullpublic void addNamespace(String prefix, String uri) throws JaxenException
Namespace prefix-to-URI mappings in an XPath are independant of those used within any document. Only the mapping explicitly added to this XPath will be available for resolving the XPath expression.
This is a convenience method for adding mappings to the
default NamespaceContext
in place for this XPath.
If you have installed a specific custom NamespaceContext
,
then this method will throw a JaxenException
.
prefix
- The namespace prefix.uri
- The namespace URI.JaxenException
- If a NamespaceContext
used by this XPath has been explicitly installed.public void setNamespaceContext(NamespaceContext namespaceContext)
NamespaceContext
for use with this
XPath expression.
A NamespaceContext
is responsible for translating
namespace prefixes within the expression into namespace URIs.
namespaceContext
- The NamespaceContext
to
install for this expression.NamespaceContext
,
NamespaceContext.translateNamespacePrefixToUri(java.lang.String)
public void setFunctionContext(FunctionContext functionContext)
FunctionContext
for use with this XPath
expression.
A FunctionContext
is responsible for resolving
all function calls used within the expression.
functionContext
- The FunctionContext
to
install for this expression.FunctionContext
,
FunctionContext.getFunction(java.lang.String, java.lang.String, java.lang.String)
public void setVariableContext(VariableContext variableContext)
VariableContext
for use with this XPath
expression.
A VariableContext
is responsible for resolving
all variables referenced within the expression.
variableContext
- The VariableContext
to
install for this expression.VariableContext
,
VariableContext.getVariableValue(java.lang.String, java.lang.String, java.lang.String)
public NamespaceContext getNamespaceContext()
NamespaceContext
used by this XPath
expression.
A FunctionContext
is responsible for resolving
all function calls used within the expression.
If this XPath expression has not previously had a NamespaceContext
installed, a new default NamespaceContext
will be created,
installed and returned.
NamespaceContext
used by this expression.NamespaceContext
public FunctionContext getFunctionContext()
FunctionContext
used by this XPath
expression.
A FunctionContext
is responsible for resolving
all function calls used within the expression.
If this XPath expression has not previously had a FunctionContext
installed, a new default FunctionContext
will be created,
installed and returned.
FunctionContext
used by this expression.FunctionContext
public VariableContext getVariableContext()
VariableContext
used by this XPath
expression.
A VariableContext
is responsible for resolving
all variables referenced within the expression.
If this XPath expression has not previously had a VariableContext
installed, a new default VariableContext
will be created,
installed and returned.
VariableContext
used by this expression.VariableContext
public Navigator getNavigator()
Navigator
for us in evaluating this XPath expression.Navigator
.
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