javax.xml.xpath.XPathFactory Maven / Gradle / Ivy
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* (the "License"). You may not use this file except
* in compliance with the License.
*
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* https://jaxp.dev.java.net/CDDLv1.0.html.
* See the License for the specific language governing
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*
* When distributing Covered Code, include this CDDL
* HEADER in each file and include the License file at
* https://jaxp.dev.java.net/CDDLv1.0.html
* If applicable add the following below this CDDL HEADER
* with the fields enclosed by brackets "[]" replaced with
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/*
* $Id: XPathFactory.java,v 1.5 2006/05/19 01:08:43 jeffsuttor Exp $
* %W% %E%
*
* Copyright 2005 Sun Microsystems, Inc. All Rights Reserved.
*/
package javax.xml.xpath;
/**
* An XPathFactory instance can be used to create
* {@link javax.xml.xpath.XPath} objects.
*
*See {@link #newInstance(String uri)} for lookup mechanism.
*
* The {@link XPathFactory} class is not thread-safe. In other words,
* it is the application's responsibility to ensure that at most
* one thread is using a {@link XPathFactory} object at any
* given moment. Implementations are encouraged to mark methods
* as synchronized to protect themselves from broken clients.
*
*
{@link XPathFactory} is not re-entrant. While one of the
* newInstance methods is being invoked, applications
* may not attempt to recursively invoke a newInstance method,
* even from the same thread.
*
* @author Norman Walsh
* @author Jeff Suttor
*
* @version $Revision: 1.5 $, $Date: 2006/05/19 01:08:43 $
* @since 1.5
*/
public abstract class XPathFactory {
/**
*
The default property name according to the JAXP spec.
*/
public static final String DEFAULT_PROPERTY_NAME = "javax.xml.xpath.XPathFactory";
/**
* Default Object Model URI.
*/
public static final String DEFAULT_OBJECT_MODEL_URI = "http://java.sun.com/jaxp/xpath/dom";
/**
* Take care of restrictions imposed by java security model
*/
private static SecuritySupport ss = new SecuritySupport() ;
/**
* Protected constructor as {@link #newInstance()} or {@link #newInstance(String uri)}
* or {@link #newInstance(String uri, String factoryClassName, ClassLoader classLoader)}
* should be used to create a new instance of an XPathFactory.
*/
protected XPathFactory() {
}
/**
* Get a new XPathFactory instance using the default object model,
* {@link #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.
*
* @return Instance of an XPathFactory.
*
* @throws RuntimeException When there is a failure in creating an
* XPathFactory for the default object model.
*/
public static final XPathFactory newInstance() {
try {
return newInstance(DEFAULT_OBJECT_MODEL_URI);
} catch (XPathFactoryConfigurationException xpathFactoryConfigurationException) {
throw new RuntimeException(
"XPathFactory#newInstance() failed to create an XPathFactory for the default object model: "
+ DEFAULT_OBJECT_MODEL_URI
+ " with the XPathFactoryConfigurationException: "
+ xpathFactoryConfigurationException.toString()
);
}
}
/**
* 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 {@link #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:
*
* {@link #isObjectModelSupported(String objectModel)}
*
* 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. {@link #DEFAULT_OBJECT_MODEL_URI}.
*
*
* If everything fails, an XPathFactoryConfigurationException will be thrown.
*
* Tip for Trouble-shooting:
* See {@link java.util.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
*
*
* @param uri Identifies the underlying object model.
* The specification only defines the URI {@link #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.
*
* @return Instance of an XPathFactory.
*
* @throws XPathFactoryConfigurationException If the specified object model is unavailable.
* @throws NullPointerException If uri is null.
* @throws IllegalArgumentException If uri is null
* or uri.length() == 0.
*/
public static final XPathFactory newInstance(final String uri)
throws XPathFactoryConfigurationException {
if (uri == null) {
throw new NullPointerException(
"XPathFactory#newInstance(String uri) cannot be called with uri == null"
);
}
if (uri.length() == 0) {
throw new IllegalArgumentException(
"XPathFactory#newInstance(String uri) cannot be called with uri == \"\""
);
}
ClassLoader classLoader = ss.getContextClassLoader();
if (classLoader == null) {
//use the current class loader
classLoader = XPathFactory.class.getClassLoader();
}
XPathFactory xpathFactory = new XPathFactoryFinder(classLoader).newFactory(uri);
if (xpathFactory == null) {
throw new XPathFactoryConfigurationException(
"No XPathFactory implementation found for the object model: "
+ uri
);
}
return xpathFactory;
}
/**
* Obtain a new instance of a XPathFactory from a factory class name. XPathFactory
* is 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.debug system property will cause
* this method to print a lot of debug messages
* to System.err about what it is doing and where it is looking at.
*
* If you have problems try:
*
* java -Djaxp.debug=1 YourProgram ....
*
*
* @param uri Identifies the underlying object model. The specification only defines the URI
* {@link #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.
*
* @param factoryClassName fully qualified factory class name that provides implementation of javax.xml.xpath.XPathFactory.
*
* @param classLoader ClassLoader used to load the factory class. If null
* current Thread's context classLoader is used to load the factory class.
*
*
* @return New instance of a XPathFactory
*
* @throws XPathFactoryConfigurationException
* if factoryClassName is null, or
* the factory class cannot be loaded, instantiated
* or the factory class does not support the object model specified
* in the uri parameter.
*
* @throws NullPointerException If uri is null.
* @throws IllegalArgumentException If uri is null
* or uri.length() == 0.
*
* @see #newInstance()
* @see #newInstance(String uri)
*
* @since 1.6
*/
public static XPathFactory newInstance(String uri, String factoryClassName, ClassLoader classLoader)
throws XPathFactoryConfigurationException{
ClassLoader cl = classLoader;
if (uri == null) {
throw new NullPointerException(
"XPathFactory#newInstance(String uri) cannot be called with uri == null"
);
}
if (uri.length() == 0) {
throw new IllegalArgumentException(
"XPathFactory#newInstance(String uri) cannot be called with uri == \"\""
);
}
if (cl == null) {
cl = ss.getContextClassLoader();
}
XPathFactory f = new XPathFactoryFinder(cl).createInstance(factoryClassName);
if (f == null) {
throw new XPathFactoryConfigurationException(
"No XPathFactory implementation found for the object model: "
+ uri
);
}
//if this factory supports the given schemalanguage return this factory else thrown exception
if(f.isObjectModelSupported(uri)){
return f;
}else{
throw new XPathFactoryConfigurationException("Factory " + factoryClassName + " doesn't support given " + uri + " object model");
}
}
/**
* Is specified object model supported by this XPathFactory?
*
* @param objectModel Specifies the object model which the returned XPathFactory will understand.
*
* @return true if XPathFactory supports objectModel, else false.
*
* @throws NullPointerException If objectModel is null.
* @throws IllegalArgumentException If objectModel.length() == 0.
*/
public abstract boolean isObjectModelSupported(String objectModel);
/**
* Set a feature for this XPathFactory and
* XPaths created by this factory.
*
*
* Feature names are fully qualified {@link java.net.URI}s.
* Implementations may define their own features.
* An {@link 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.
*
*
*
* All implementations are required to support the {@link javax.xml.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 {@link XPathFunctionResolver}
* and must throw an {@link XPathFunctionException}.
*
*
* @param name Feature name.
* @param value Is feature state true or false.
*
* @throws XPathFactoryConfigurationException if this XPathFactory or the XPaths
* it creates cannot support this feature.
* @throws NullPointerException if name is null.
*/
public abstract void setFeature(String name, boolean value)
throws XPathFactoryConfigurationException;
/**
* Get the state of the named feature.
*
*
* Feature names are fully qualified {@link java.net.URI}s.
* Implementations may define their own features.
* An {@link 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.
*
*
* @param name Feature name.
*
* @return State of the named feature.
*
* @throws XPathFactoryConfigurationException if this
* XPathFactory or the XPaths
* it creates cannot support this feature.
* @throws NullPointerException if name is null.
*/
public abstract boolean getFeature(String name)
throws XPathFactoryConfigurationException;
/**
* 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.
*
* @param resolver Variable resolver.
*
* @throws NullPointerException If resolver is
* null.
*/
public abstract void setXPathVariableResolver(XPathVariableResolver 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.
*
* @param resolver XPath function resolver.
*
* @throws NullPointerException If resolver is
* null.
*/
public abstract void setXPathFunctionResolver(XPathFunctionResolver resolver);
/**
* Return a new XPath using the underlying object
* model determined when the XPathFactory was instantiated.
*
* @return New instance of an XPath.
*/
public abstract XPath newXPath();
}