XPathFactory

public abstract class XPathFactory extends Object

An XPathFactory instance can be used to create XPath objects.

See newInstance(String) for lookup mechanism.

Constant Summary

String	DEFAULT_OBJECT_MODEL_URI	Default Object Model URI.
String	DEFAULT_PROPERTY_NAME	The default property name according to the JAXP spec.

Protected Constructor Summary

XPathFactory()

Protected constructor as newInstance(), newInstance(String) or newInstance(String, String, ClassLoader) should be used to create a new instance of an XPathFactory.

Public Method Summary

abstract boolean	getFeature(String name) Get the state of the named feature.
abstract boolean	isObjectModelSupported(String objectModel) Is specified object model supported by this `XPathFactory`?
final static XPathFactory	newInstance() Get a new `XPathFactory` instance using the default object model, `DEFAULT_OBJECT_MODEL_URI`, the W3C DOM.
static XPathFactory	newInstance(String uri, String factoryClassName, ClassLoader classLoader)
final static XPathFactory	newInstance(String uri) Get a new `XPathFactory` instance using the specified object model.
abstract XPath	newXPath() Return a new `XPath` using the underlying object model determined when the `XPathFactory` was instantiated.
abstract void	setFeature(String name, boolean value) Set a feature for this `XPathFactory` and `XPath`s created by this factory.
abstract void	setXPathFunctionResolver(XPathFunctionResolver resolver) Establish a default function resolver.
abstract void	setXPathVariableResolver(XPathVariableResolver resolver) Establish a default variable resolver.

Inherited Method Summary

From class java.lang.Object

Object	clone() Creates and returns a copy of this `Object`.
boolean	equals(Object obj) Compares this instance with the specified object and indicates if they are equal.
void	finalize() Invoked when the garbage collector has detected that this instance is no longer reachable.
final Class<?>	getClass() Returns the unique instance of `Class` that represents this object's class.
int	hashCode() Returns an integer hash code for this object.
final void	notify() Causes a thread which is waiting on this object's monitor (by means of calling one of the `wait()` methods) to be woken up.
final void	notifyAll() Causes all threads which are waiting on this object's monitor (by means of calling one of the `wait()` methods) to be woken up.
String	toString() Returns a string containing a concise, human-readable description of this object.
final void	wait(long timeout, int nanos) Causes the calling thread to wait until another thread calls the `notify()` or `notifyAll()` method of this object or until the specified timeout expires.
final void	wait(long timeout) Causes the calling thread to wait until another thread calls the `notify()` or `notifyAll()` method of this object or until the specified timeout expires.
final void	wait() Causes the calling thread to wait until another thread calls the `notify()` or `notifyAll()` method of this object.

Constants

public static final String DEFAULT_OBJECT_MODEL_URI

Default Object Model URI.

Constant Value: "http://java.sun.com/jaxp/xpath/dom"

public static final String DEFAULT_PROPERTY_NAME

The default property name according to the JAXP spec.

Constant Value: "javax.xml.xpath.XPathFactory"

Protected Constructors

protected XPathFactory ()

Protected constructor as newInstance(), newInstance(String) or newInstance(String, String, ClassLoader) should be used to create a new instance of an XPathFactory.

Public Methods

public abstract boolean getFeature (String name)

Get the state of the named feature.

Feature names are fully qualified URIs. Implementations may define their own features. An XPathFactoryConfigurationException is thrown if this XPathFactory or the XPaths 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	Feature name.

Returns

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`.

public abstract boolean isObjectModelSupported (String objectModel)

Is specified object model supported by this XPathFactory?

Parameters

objectModel	Specifies the object model which the returned `XPathFactory` will understand.

Returns

true if XPathFactory supports objectModel, else false.

Throws

NullPointerException	If `objectModel` is `null`.
IllegalArgumentException	If `objectModel.length() == 0`.

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

Instance of an XPathFactory.

public static XPathFactory newInstance (String uri, String factoryClassName, ClassLoader classLoader)

Parameters

uri
factoryClassName
classLoader

Returns

Instance of an XPathFactory.

Throws

XPathFactoryConfigurationException	If the specified object model is unavailable.
NullPointerException	If `uri` is `null`.
IllegalArgumentException	If `uri.length() == 0`.

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:
```
       isObjectModelSupported(String)
     
```
The first service provider found in class loader order that supports the specified object model is returned.
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	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

Instance of an XPathFactory.

Throws

XPathFactoryConfigurationException	If the specified object model is unavailable.
NullPointerException	If `uri` is `null`.
IllegalArgumentException	If `uri.length() == 0`.

public abstract XPath newXPath ()

Return a new XPath using the underlying object model determined when the XPathFactory was instantiated.

Returns

New instance of an XPath.

public abstract void setFeature (String name, boolean value)

Set a feature for this XPathFactory and XPaths created by this factory.

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	Feature name.
value	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`.

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	XPath function resolver.

Throws

NullPointerException	If `resolver` is `null`.

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	Variable resolver.

Throws

NullPointerException	If `resolver` is `null`.