Xalan: The org.apache.xml.dtm.DTMManager Class

Direct Known Subclasses:org.apache.xml.dtm.ref.DTMManagerDefault, org.apache.xpath.XPathContext

Members

Overview

This is a abstract class. A DTMManager instance can be used to create DTM and DTMIterator objects, and manage the DTM objects in the system.

The system property that determines which Factory implementation to create is named "org.apache.xml.utils.DTMFactory". This property names a concrete subclass of the DTMFactory abstract class. If the property is not defined, a platform default is be used.

An instance of this class must be safe to use across thread instances. It is expected that a client will create a single instance of a DTMManager to use across multiple threads. This will allow sharing of DTMs across multiple processes.

Note: this class is incomplete right now. It will be pretty much modeled after javax.xml.transform.TransformerFactory in terms of its factory support. So I have given example of how to create it.

Method Overviews

All methods in this class are abstract. So depending upon the system property of Factory class, a concrete instance will get created and that will support all methods. Please look into newInstance() method to know the look up procedure.

Example of creating a DTM Manager using newInstance(XMLStringFactory xsf)

                              throws DTMConfigurationException:

Obtain a new instance of a DTMManager. This static method creates a new factory instance This method uses the following ordered lookup procedure to determine the DTMManager implementation class to load:

Use the org.apache.xml.dtm.DTMManager system property.

Use the JAVA_HOME(the parent directory where jdk is installed)/lib/xalan.properties for a property file that contains the name of the implementation class keyed on the same value as the system property defined above.

Use the Services API (as detailed in the JAR specification), if available, to determine the classname. The Services API will look for a classname in the file META-INF/services/org.apache.xml.dtm.DTMManager in jars available to the runtime.

Use the default DTMManager classname, which is org.apache.xml.dtm.ref.DTMManagerDefault.

Once an application has obtained a reference to a DTMManager it can use the factory to configure and obtain parser instances.

Note: If it fails to load a concrete factory class, then it will throw NPE.

        XMLStringFactoryDefault stringFactory = new XMLStringFactoryDefault();

        DTMManager dtmManager = DTMManager.newInstance(stringFactory);

Example of createDocumentFragment():

This method creates a DTM representing an empty DocumentFragment object.

            DTM dtm = dtmManager.createDocumentFragment();

Note: This class is still incomplete. The DTM API is still Subject To Change. This wouldn't affect most users, but might require updating some extensions.