The default property name according to the JAXP spec.

Default Object Model URI.

 protected XPathFactory() 
{

}

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

 abstract public boolean getFeature(String name) throws XPathFactoryConfigurationException
Get the state of the named feature.


Feature names are fully qualified java.net.URI s.
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.

 abstract public boolean isObjectModelSupported(String objectModel)
Is specified object model supported by this XPathFactory?

 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 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.

 public static final XPathFactory newInstance(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;
}

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:

1. 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.
2. ${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.
3. 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 objectModel) 
   

   The first service provider found in class loader order that supports the specified object model is returned.
4. 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 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

 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");
        }
}

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 ....

 abstract public XPath newXPath()
Return a new XPath using the underlying object
model determined when the XPathFactory was instantiated.

 abstract public  void setFeature(String name,
    boolean value) throws XPathFactoryConfigurationException
Set a feature for this XPathFactory and
XPaths created by this factory.


Feature names are fully qualified java.net.URI s.
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.



All implementations are required to support the 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 XPathFunctionResolver 
and must throw an XPathFunctionException .

 abstract public  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.

 abstract public  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.