/* * Copyright (c) 2003, 2016, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package javax.xml.xpath; import com.sun.org.apache.xpath.internal.jaxp.XPathFactoryImpl; import jdk.xml.internal.SecuritySupport; /** *
An {@code 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
*
* @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"; /** *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 {@code XPathFactory}.
*/ protected XPathFactory() { } /** * Creates a new instance of the {@code XPathFactory} builtin * system-default implementation. * * @implSpec The {@code XPathFactory} builtin * system-default implementation is only required to support the * {@link #DEFAULT_OBJECT_MODEL_URI default object model}, the * {@linkplain org.w3c.dom W3C DOM}, but may support additional * object models. * * @return A new instance of the {@code XPathFactory} builtin * system-default implementation. * * @since 9 */ public static XPathFactory newDefaultInstance() { return XPathFactoryImpl.newXPathFactoryNoServiceLoader(); } /** *Get a new {@code 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 {@code XPathFactory}. * * @throws RuntimeException When there is a failure in creating an * {@code XPathFactory} for the default object model. */ public static XPathFactory newInstance() { try { return newInstance(DEFAULT_OBJECT_MODEL_URI); } catch (XPathFactoryConfigurationException e) { throw new RuntimeException( "XPathFactory#newInstance() failed to create an XPathFactory for the default object model: " + DEFAULT_OBJECT_MODEL_URI + " with the XPathFactoryConfigurationException: " + e.getMessage(), e ); } } /** *Get a new {@code XPathFactory} instance using the specified object model.
* *To find a {@code 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. *
* Use the configuration file "jaxp.properties". The file is in standard * {@link java.util.Properties} format 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. *
* Use the service-provider loading facility, defined by the
* {@link java.util.ServiceLoader} class, to attempt to locate and load an
* implementation of the service using the {@linkplain
* java.util.ServiceLoader#load(java.lang.Class) default loading mechanism}:
* the service-provider loading facility will use the {@linkplain
* java.lang.Thread#getContextClassLoader() current thread's context class loader}
* to attempt to load the service. If the context class
* loader is null, the {@linkplain
* ClassLoader#getSystemClassLoader() system class loader} will be used.
*
* Each potential service provider is required to implement the method
* {@link #isObjectModelSupported(String objectModel)}.
* The first service provider found that supports the specified object
* model is returned.
*
* In case of {@link java.util.ServiceConfigurationError} an
* {@link XPathFactoryConfigurationException} will be thrown.
*
* Platform default {@code XPathFactory} is located in a platform * specific way. * There must be a {@linkplain #newDefaultInstance() platform default} * {@code XPathFactory} for the W3C DOM, i.e. * {@link #DEFAULT_OBJECT_MODEL_URI}. *
If everything fails, an {@code 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 {@code XPathFactory}.
*
* @throws XPathFactoryConfigurationException If the specified object model
* is unavailable, or if there is a configuration error.
* @throws NullPointerException If uri
is null
.
* @throws IllegalArgumentException If uri
is null
* or uri.length() == 0
.
*/
public static 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 = SecuritySupport.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 {@code XPathFactory} from a factory class name. {@code 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.
* * *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 {@code 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 = SecuritySupport.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 {@code XPathFactory}?
* * @param objectModel Specifies the object model which the returned {@code XPathFactory} will understand. * * @returntrue
if {@code 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 {@code XPathFactory} and
* XPath
s 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
* {@code XPathFactory} or the XPath
s
* it creates cannot support the feature.
* It is possible for an {@code 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}.
*
true
or false
.
*
* @throws XPathFactoryConfigurationException if this {@code XPathFactory} or the XPath
s
* 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
* {@code XPathFactory} or the XPath
s
* it creates cannot support the feature.
* It is possible for an {@code XPathFactory} to expose a feature value
* but be unable to change its state.
*
XPath
s
* 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
.
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
.
resolver
is
* null
.
*/
public abstract void setXPathFunctionResolver(XPathFunctionResolver resolver);
/**
* Return a new XPath
using the underlying object
* model determined when the {@code XPathFactory} was instantiated.
XPath
.
*/
public abstract XPath newXPath();
}