- java.lang.Object
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- javax.xml.xpath.XPathFactory
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public abstract class XPathFactory extends Object
An
XPathFactoryinstance can be used to createXPathobjects.See
newInstance(String uri)for lookup mechanism.The
XPathFactoryclass is not thread-safe. In other words, it is the application's responsibility to ensure that at most one thread is using aXPathFactoryobject at any given moment. Implementations are encouraged to mark methods assynchronizedto protect themselves from broken clients.XPathFactoryis not re-entrant. While one of thenewInstancemethods is being invoked, applications may not attempt to recursively invoke anewInstancemethod, even from the same thread.- Since:
- 1.5
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Field Summary
Fields Modifier and Type Field Description static StringDEFAULT_OBJECT_MODEL_URIDefault Object Model URI.static StringDEFAULT_PROPERTY_NAMEThe default property name according to the JAXP spec.
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Constructor Summary
Constructors Modifier Constructor Description protectedXPathFactory()Protected constructor asnewInstance()ornewInstance(String uri)ornewInstance(String uri, String factoryClassName, ClassLoader classLoader)should be used to create a new instance of anXPathFactory.
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Method Summary
All Methods Static Methods Instance Methods Abstract Methods Concrete Methods Modifier and Type Method Description abstract booleangetFeature(String name)Get the state of the named feature.abstract booleanisObjectModelSupported(String objectModel)Is specified object model supported by thisXPathFactory?static XPathFactorynewDefaultInstance()Creates a new instance of theXPathFactorybuiltin system-default implementation.static XPathFactorynewInstance()Get a newXPathFactoryinstance using the default object model,DEFAULT_OBJECT_MODEL_URI, the W3C DOM.static XPathFactorynewInstance(String uri)Get a newXPathFactoryinstance using the specified object model.static XPathFactorynewInstance(String uri, String factoryClassName, ClassLoader classLoader)Obtain a new instance of aXPathFactoryfrom a factory class name.abstract XPathnewXPath()Return a newXPathusing the underlying object model determined when theXPathFactorywas instantiated.abstract voidsetFeature(String name, boolean value)Set a feature for thisXPathFactoryandXPaths created by this factory.abstract voidsetXPathFunctionResolver(XPathFunctionResolver resolver)Establish a default function resolver.abstract voidsetXPathVariableResolver(XPathVariableResolver resolver)Establish a default variable resolver.
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Field Detail
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DEFAULT_PROPERTY_NAME
public static final String DEFAULT_PROPERTY_NAME
The default property name according to the JAXP spec.
- See Also:
- Constant Field Values
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DEFAULT_OBJECT_MODEL_URI
public static final String DEFAULT_OBJECT_MODEL_URI
Default Object Model URI.
- See Also:
- Constant Field Values
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Constructor Detail
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XPathFactory
protected XPathFactory()
Protected constructor as
newInstance()ornewInstance(String uri)ornewInstance(String uri, String factoryClassName, ClassLoader classLoader)should be used to create a new instance of anXPathFactory.
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Method Detail
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newDefaultInstance
public static XPathFactory newDefaultInstance()
Creates a new instance of theXPathFactorybuiltin system-default implementation.- Implementation Requirements:
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XPathFactorybuiltin system-default implementation is only required to support thedefault object model, the W3C DOM, but may support additional object models. - Returns:
- A new instance of the
XPathFactorybuiltin system-default implementation. - Since:
- 9
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newInstance
public static XPathFactory newInstance()
Get a new
XPathFactoryinstance 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. - Throws:
RuntimeException- When there is a failure in creating anXPathFactoryfor the default object model.
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newInstance
public static XPathFactory newInstance(String uri) throws XPathFactoryConfigurationException
Get a new
XPathFactoryinstance using the specified object model.To find a
XPathFactoryobject, 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. -
Use the configuration file "jaxp.properties". The file is in standard
Propertiesformat and typically located in the conf directory of the Java installation. It contains the fully qualified name of the implementation class with the key being the system property defined above.The jaxp.properties file is read only once by the JAXP implementation and its values are then cached for future use. If the file does not exist when the first attempt is made to read from it, no further attempts are made to check for its existence. It is not possible to change the value of any property in jaxp.properties after it has been read for the first time.
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Use the service-provider loading facility, defined by the
ServiceLoaderclass, to attempt to locate and load an implementation of the service using the default loading mechanism: the service-provider loading facility will use the current thread's context class loader to attempt to load the service. If the context class loader is null, the system class loader will be used.
Each potential service provider is required to implement the methodisObjectModelSupported(String objectModel). The first service provider found that supports the specified object model is returned.
In case ofServiceConfigurationErroranXPathFactoryConfigurationExceptionwill be thrown. -
Platform default
XPathFactoryis located in a platform specific way. There must be a platform defaultXPathFactoryfor the W3C DOM, i.e.DEFAULT_OBJECT_MODEL_URI.
If everything fails, an
XPathFactoryConfigurationExceptionwill 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 URIDEFAULT_OBJECT_MODEL_URI,http://java.sun.com/jaxp/xpath/domfor 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, or if there is a configuration error.NullPointerException- Ifuriisnull.IllegalArgumentException- Ifuriisnulloruri.length() == 0.
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newInstance
public static XPathFactory newInstance(String uri, String factoryClassName, ClassLoader classLoader) throws XPathFactoryConfigurationException
Obtain a new instance of a
XPathFactoryfrom a factory class name.XPathFactoryis returned if specified factory class supports the specified object model. This function is useful when there are multiple providers in the classpath. It gives more control to the application as it can specify which provider should be loaded.Tip for Trouble-shooting
Setting the
jaxp.debugsystem property will cause this method to print a lot of debug messages toSystem.errabout what it is doing and where it is looking at.If you have problems try:
java -Djaxp.debug=1 YourProgram ....
- Parameters:
uri- Identifies the underlying object model. The specification only defines the URIDEFAULT_OBJECT_MODEL_URI,http://java.sun.com/jaxp/xpath/domfor the W3C DOM, the org.w3c.dom package, and implementations are free to introduce other URIs for other object models.factoryClassName- fully qualified factory class name that provides implementation ofjavax.xml.xpath.XPathFactory.classLoader-ClassLoaderused to load the factory class. IfnullcurrentThread's context classLoader is used to load the factory class.- Returns:
- New instance of a
XPathFactory - Throws:
XPathFactoryConfigurationException- iffactoryClassNameisnull, or the factory class cannot be loaded, instantiated or the factory class does not support the object model specified in theuriparameter.NullPointerException- Ifuriisnull.IllegalArgumentException- Ifuriisnulloruri.length() == 0.- Since:
- 1.6
- See Also:
newInstance(),newInstance(String uri)
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isObjectModelSupported
public abstract boolean isObjectModelSupported(String objectModel)
Is specified object model supported by this
XPathFactory?- Parameters:
objectModel- Specifies the object model which the returnedXPathFactorywill understand.- Returns:
trueifXPathFactorysupportsobjectModel, elsefalse.- Throws:
NullPointerException- IfobjectModelisnull.IllegalArgumentException- IfobjectModel.length() == 0.
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setFeature
public abstract void setFeature(String name, boolean value) throws XPathFactoryConfigurationException
Set a feature for this
XPathFactoryandXPaths created by this factory.Feature names are fully qualified
URIs. Implementations may define their own features. AnXPathFactoryConfigurationExceptionis thrown if thisXPathFactoryor theXPaths it creates cannot support the feature. It is possible for anXPathFactoryto expose a feature value but be unable to change its state.All implementations are required to support the
XMLConstants.FEATURE_SECURE_PROCESSINGfeature. When the feature istrue, any reference to an external function is an error. Under these conditions, the implementation must not call theXPathFunctionResolverand must throw anXPathFunctionException.- Parameters:
name- Feature name.value- Is feature statetrueorfalse.- Throws:
XPathFactoryConfigurationException- if thisXPathFactoryor theXPaths it creates cannot support this feature.NullPointerException- ifnameisnull.
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getFeature
public abstract boolean getFeature(String name) throws XPathFactoryConfigurationException
Get the state of the named feature.
Feature names are fully qualified
URIs. Implementations may define their own features. AnXPathFactoryConfigurationExceptionis thrown if thisXPathFactoryor theXPaths it creates cannot support the feature. It is possible for anXPathFactoryto expose a feature value but be unable to change its state.- Parameters:
name- Feature name.- Returns:
- State of the named feature.
- Throws:
XPathFactoryConfigurationException- if thisXPathFactoryor theXPaths it creates cannot support this feature.NullPointerException- ifnameisnull.
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setXPathVariableResolver
public abstract void setXPathVariableResolver(XPathVariableResolver resolver)
Establish a default variable resolver.
Any
XPathobjects constructed from this factory will use the specified resolver by default.A
NullPointerExceptionis thrown ifresolverisnull.- Parameters:
resolver- Variable resolver.- Throws:
NullPointerException- Ifresolverisnull.
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setXPathFunctionResolver
public abstract void setXPathFunctionResolver(XPathFunctionResolver resolver)
Establish a default function resolver.
Any
XPathobjects constructed from this factory will use the specified resolver by default.A
NullPointerExceptionis thrown ifresolverisnull.- Parameters:
resolver- XPath function resolver.- Throws:
NullPointerException- Ifresolverisnull.
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newXPath
public abstract XPath newXPath()
Return a new
XPathusing the underlying object model determined when theXPathFactorywas instantiated.- Returns:
- New instance of an
XPath.
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