XPathFactory
public
abstract
class
XPathFactory
extends Object
java.lang.Object | |
↳ | javax.xml.xpath.XPathFactory |
An XPathFactory
instance can be used to create
XPath
objects.
See newInstance(java.lang.String)
for lookup mechanism.
Summary
Constants | |
---|---|
String |
DEFAULT_OBJECT_MODEL_URI
Default Object Model URI. |
String |
DEFAULT_PROPERTY_NAME
The default property name according to the JAXP spec. |
Protected constructors | |
---|---|
XPathFactory()
Protected constructor as |
Public methods | |
---|---|
abstract
boolean
|
getFeature(String name)
Get the state of the named feature. |
abstract
boolean
|
isObjectModelSupported(String objectModel)
Is specified object model supported by this |
static
final
XPathFactory
|
newInstance()
Get a new |
static
XPathFactory
|
newInstance(String uri, String factoryClassName, ClassLoader classLoader)
|
static
final
XPathFactory
|
newInstance(String uri)
Get a new |
abstract
XPath
|
newXPath()
Return a new |
abstract
void
|
setFeature(String name, boolean value)
Set a feature for this |
abstract
void
|
setXPathFunctionResolver(XPathFunctionResolver resolver)
Establish a default function resolver. |
abstract
void
|
setXPathVariableResolver(XPathVariableResolver resolver)
Establish a default variable resolver. |
Inherited methods | |
---|---|
Constants
DEFAULT_OBJECT_MODEL_URI
public static final String DEFAULT_OBJECT_MODEL_URI
Default Object Model URI.
Constant Value: "http://java.sun.com/jaxp/xpath/dom"
DEFAULT_PROPERTY_NAME
public static final String DEFAULT_PROPERTY_NAME
The default property name according to the JAXP spec.
Constant Value: "javax.xml.xpath.XPathFactory"
Protected constructors
XPathFactory
protected XPathFactory ()
Protected constructor as newInstance()
, newInstance(java.lang.String)
or newInstance(java.lang.String, java.lang.String, java.lang.ClassLoader)
should be used to create a new instance of an XPathFactory
.
Public methods
getFeature
public abstract boolean getFeature (String name)
Get the state of the named feature.
Feature names are fully qualified URI
s.
Implementations may define their own features.
An XPathFactoryConfigurationException
is thrown if this XPathFactory
or the XPath
s
it creates cannot support the feature.
It is possible for an XPathFactory
to expose a feature value but be unable to change its state.
Parameters | |
---|---|
name |
String : Feature name. |
Returns | |
---|---|
boolean |
State of the named feature. |
Throws | |
---|---|
XPathFactoryConfigurationException |
if this XPathFactory or the XPath s
it creates cannot support this feature. |
NullPointerException |
if name is null . |
isObjectModelSupported
public abstract boolean isObjectModelSupported (String objectModel)
Is specified object model supported by this XPathFactory
?
Parameters | |
---|---|
objectModel |
String : Specifies the object model which the returned XPathFactory will understand. |
Returns | |
---|---|
boolean |
true if XPathFactory supports objectModel , else false . |
Throws | |
---|---|
NullPointerException |
If objectModel is null . |
IllegalArgumentException |
If objectModel.length() == 0 . |
newInstance
public static final XPathFactory newInstance ()
Get a new XPathFactory
instance using the default object model,
DEFAULT_OBJECT_MODEL_URI
,
the W3C DOM.
This method is functionally equivalent to:
newInstance(DEFAULT_OBJECT_MODEL_URI)
Since the implementation for the W3C DOM is always available, this method will never fail.
Returns | |
---|---|
XPathFactory |
Instance of an XPathFactory . |
newInstance
public static XPathFactory newInstance (String uri, String factoryClassName, ClassLoader classLoader)
Parameters | |
---|---|
uri |
String |
factoryClassName |
String |
classLoader |
ClassLoader |
Returns | |
---|---|
XPathFactory |
Instance of an XPathFactory . |
Throws | |
---|---|
XPathFactoryConfigurationException |
If the specified object model is unavailable. |
NullPointerException |
If uri is null . |
IllegalArgumentException |
If uri.length() == 0 . |
newInstance
public static final XPathFactory newInstance (String uri)
Get a new XPathFactory
instance using the specified object model.
To find a XPathFactory
object,
this method looks the following places in the following order where "the class loader" refers to the context class loader:
-
If the system property
DEFAULT_PROPERTY_NAME
+ ":uri" is present, where uri is the parameter to this method, then its value is read as a class name. The method will try to create a new instance of this class by using the class loader, and returns it if it is successfully created. - ${java.home}/lib/jaxp.properties is read and the value associated with the key being the system property above is looked for. If present, the value is processed just like above.
-
The class loader is asked for service provider provider-configuration files matching
javax.xml.xpath.XPathFactory
in the resource directory META-INF/services. See the JAR File Specification for file format and parsing rules. Each potential service provider is required to implement the method: The first service provider found in class loader order that supports the specified object model is returned.isObjectModelSupported(java.lang.String)
-
Platform default
XPathFactory
is located in a platform specific way. There must be a platform default XPathFactory for the W3C DOM, i.e.DEFAULT_OBJECT_MODEL_URI
.
If everything fails, an XPathFactoryConfigurationException
will be thrown.
Tip for Trouble-shooting:
See Properties.load(java.io.InputStream)
for exactly how a property file is parsed.
In particular, colons ':' need to be escaped in a property file, so make sure the URIs are properly escaped in it.
For example:
http\://java.sun.com/jaxp/xpath/dom=org.acme.DomXPathFactory
Parameters | |
---|---|
uri |
String : Identifies the underlying object model.
The specification only defines the URI DEFAULT_OBJECT_MODEL_URI ,
http://java.sun.com/jaxp/xpath/dom for the W3C DOM,
the org.w3c.dom package, and implementations are free to introduce other URIs for other object models. |
Returns | |
---|---|
XPathFactory |
Instance of an XPathFactory . |
Throws | |
---|---|
XPathFactoryConfigurationException |
If the specified object model is unavailable. |
NullPointerException |
If uri is null . |
IllegalArgumentException |
If uri.length() == 0 . |
newXPath
public abstract XPath newXPath ()
Return a new XPath
using the underlying object
model determined when the XPathFactory
was instantiated.
Returns | |
---|---|
XPath |
New instance of an XPath . |
setFeature
public abstract void setFeature (String name, boolean value)
Set a feature for this XPathFactory
and XPath
s created by this factory.
Feature names are fully qualified URI
s.
Implementations may define their own features.
An XPathFactoryConfigurationException
is thrown if this XPathFactory
or the XPath
s
it creates cannot support the feature.
It is possible for an XPathFactory
to expose a feature value but be unable to change its state.
All implementations are required to support the XMLConstants.FEATURE_SECURE_PROCESSING
feature.
When the feature is true
, any reference to an external function is an error.
Under these conditions, the implementation must not call the XPathFunctionResolver
and must throw an XPathFunctionException
.
Parameters | |
---|---|
name |
String : Feature name. |
value |
boolean : Is feature state true or false . |
Throws | |
---|---|
XPathFactoryConfigurationException |
if this XPathFactory or the XPath s
it creates cannot support this feature. |
NullPointerException |
if name is null . |
setXPathFunctionResolver
public abstract void setXPathFunctionResolver (XPathFunctionResolver resolver)
Establish a default function resolver.
Any XPath
objects constructed from this factory will use
the specified resolver by default.
A NullPointerException
is thrown if resolver
is null
.
Parameters | |
---|---|
resolver |
XPathFunctionResolver : XPath function resolver. |
Throws | |
---|---|
NullPointerException |
If resolver is null . |
setXPathVariableResolver
public abstract void setXPathVariableResolver (XPathVariableResolver resolver)
Establish a default variable resolver.
Any XPath
objects constructed from this factory will use
the specified resolver by default.
A NullPointerException
is thrown if resolver
is null
.
Parameters | |
---|---|
resolver |
XPathVariableResolver : Variable resolver. |
Throws | |
---|---|
NullPointerException |
If resolver is null . |