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
Note: this class is incomplete right now. It will be pretty much * modeled after javax.xml.transform.TransformerFactory in terms of its * factory support.
* *State: In progress!!
*/ public abstract class DTMManager { /** The default property name to load the manager. */ private static final String defaultPropName = "org.apache.xml.dtm.DTMManager"; /** * Factory for creating XMLString objects. * %TBD% Make this set by the caller. */ protected XMLStringFactory m_xsf = null; /** * Default constructor is protected on purpose. */ protected DTMManager(){} /** * Get the XMLStringFactory used for the DTMs. * * * @return a valid XMLStringFactory object, or null if it hasn't been set yet. */ public XMLStringFactory getXMLStringFactory() { return m_xsf; } /** * Set the XMLStringFactory used for the DTMs. * * * @param xsf a valid XMLStringFactory object, should not be null. */ public void setXMLStringFactory(XMLStringFactory xsf) { m_xsf = xsf; } /** * Obtain a new instance of aDTMManager.
* This static method creates a new factory instance
* This method uses the following ordered lookup procedure to determine
* the DTMManager implementation class to
* load:
* javax.xml.parsers.DocumentBuilderFactory system
* property.
* META-INF/services/javax.xml.parsers.DTMManager
* in jars available to the runtime.
* DTMManager instance.
*
* DTMManager it can use the factory to configure
* and obtain parser instances.
*
* @return new DTMManager instance, never null.
*
* @throws DTMConfigurationException
* if the implmentation is not available or cannot be instantiated.
*/
public static DTMManager newInstance(XMLStringFactory xsf)
throws DTMConfigurationException
{
String classname = findFactory(defaultPropName,
"org.apache.xml.dtm.ref.DTMManagerDefault");
if (classname == null)
{
throw new DTMConfigurationException("No default implementation found");
}
DTMManager factoryImpl;
try
{
Class clazz = Class.forName(classname);
factoryImpl = (DTMManager) clazz.newInstance();
}
catch (ClassNotFoundException cnfe)
{
throw new DTMConfigurationException(cnfe);
}
catch (IllegalAccessException iae)
{
throw new DTMConfigurationException(iae);
}
catch (InstantiationException ie)
{
throw new DTMConfigurationException(ie);
}
factoryImpl.setXMLStringFactory(xsf);
return factoryImpl;
}
/**
* Get an instance of a DTM, loaded with the content from the
* specified source. If the unique flag is true, a new instance will
* always be returned. Otherwise it is up to the DTMManager to return a
* new instance or an instance that it already created and may be being used
* by someone else.
* (I think more parameters will need to be added for error handling, and entity
* resolution).
*
* @param source the specification of the source object, which may be null,
* in which case it is assumed that node construction will take
* by some other means.
* @param unique true if the returned DTM must be unique, probably because it
* is going to be mutated.
* @param whiteSpaceFilter Enables filtering of whitespace nodes, and may
* be null.
* @param incremental true if the DTM should be built incrementally, if
* possible.
* @param doIndexing true if the caller considers it worth it to use
* indexing schemes.
*
* @return a non-null DTM reference.
*/
public abstract DTM getDTM(javax.xml.transform.Source source,
boolean unique, DTMWSFilter whiteSpaceFilter,
boolean incremental, boolean doIndexing);
/**
* Get the instance of DTM that "owns" a node handle.
*
* @param nodeHandle the nodeHandle.
*
* @return a non-null DTM reference.
*/
public abstract DTM getDTM(int nodeHandle);
/**
* Given a W3C DOM node, try and return a DTM handle.
* Note: calling this may be non-optimal.
*
* @param node Non-null reference to a DOM node.
*
* @return a valid DTM handle.
*/
public abstract int getDTMHandleFromNode(org.w3c.dom.Node node);
/**
* Creates a DTM representing an empty DocumentFragment object.
* @return a non-null DTM reference.
*/
public abstract DTM createDocumentFragment();
/**
* Release a DTM either to a lru pool, or completely remove reference.
* DTMs without system IDs are always hard deleted.
* State: experimental.
*
* @param dtm The DTM to be released.
* @param shouldHardDelete True if the DTM should be removed no matter what.
* @return true if the DTM was removed, false if it was put back in a lru pool.
*/
public abstract boolean release(DTM dtm, boolean shouldHardDelete);
/**
* Create a new DTMIterator based on an XPath
* UnionExpr.
*
* @param xpathCompiler ??? Somehow we need to pass in a subpart of the
* expression. I hate to do this with strings, since the larger expression
* has already been parsed.
*
* @param pos The position in the expression.
* @return The newly created DTMIterator.
*/
public abstract DTMIterator createDTMIterator(Object xpathCompiler,
int pos);
/**
* Create a new DTMIterator based on an XPath
* UnionExpr.
*
* @param xpathString Must be a valid string expressing a
* UnionExpr.
*
* @param presolver An object that can resolve prefixes to namespace URLs.
*
* @return The newly created DTMIterator.
*/
public abstract DTMIterator createDTMIterator(String xpathString,
PrefixResolver presolver);
/**
* Create a new DTMIterator based only on a whatToShow
* and a DTMFilter. The traversal semantics are defined as the
* descendant access.
*
* Note that DTMIterators may not be an exact match to DOM
* NodeIterators. They are initialized and used in much the same way
* as a NodeIterator, but their response to document mutation is not
* currently defined.
*
* @param whatToShow This flag specifies which node types may appear in
* the logical view of the tree presented by the iterator. See the
* description of NodeFilter for the set of possible
* SHOW_ values.These flags can be combined using
* OR.
* @param filter The NodeFilter to be used with this
* DTMFilter, or null to indicate no filter.
* @param entityReferenceExpansion The value of this flag determines
* whether entity reference nodes are expanded.
*
* @return The newly created DTMIterator.
*/
public abstract DTMIterator createDTMIterator(int whatToShow,
DTMFilter filter, boolean entityReferenceExpansion);
/**
* Create a new DTMIterator that holds exactly one node.
*
* @param node The node handle that the DTMIterator will iterate to.
*
* @return The newly created DTMIterator.
*/
public abstract DTMIterator createDTMIterator(int node);
/* Flag indicating whether an incremental transform is desired */
public static boolean m_incremental = false;
/**
* Set a flag indicating whether an incremental transform is desired
* @param incremental boolean to use to set m_incremental.
*
*/
public static void setIncremental(boolean incremental)
{
m_incremental = incremental;
}
// -------------------- private methods --------------------
/**
* Avoid reading all the files when the findFactory
* method is called the second time (cache the result of
* finding the default impl).
*/
private static String foundFactory = null;
/**
* Temp debug code - this will be removed after we test everything
*/
private static boolean debug;
static
{
try
{
debug = System.getProperty("dtm.debug") != null;
}
catch (SecurityException ex){}
}
/**
* Private implementation method - will find the implementation
* class in the specified order.
*
* @param factoryId Name of the factory interface.
* @param xmlProperties Name of the properties file based on JAVA/lib.
* @param defaultFactory Default implementation, if nothing else is found.
*
* @return The factory class name.
*/
private static String findFactory(String factoryId, String defaultFactory)
{
// Use the system property first
try
{
String systemProp = null;
try
{
systemProp = System.getProperty(factoryId);
}
catch (SecurityException se){}
if (systemProp != null)
{
if (debug)
{
System.err.println("DTM: found system property" + systemProp);
}
return systemProp;
}
}
catch (SecurityException se){}
if (foundFactory != null)
{
return foundFactory;
}
// try to read from $java.home/lib/jaxp.properties
try
{
String javah = System.getProperty("java.home");
String configFile = javah + File.separator + "lib" + File.separator
+ "jaxp.properties";
File f = new File(configFile);
if (f.exists())
{
Properties props = new Properties();
props.load(new FileInputStream(f));
foundFactory = props.getProperty(factoryId);
if (debug)
{
System.err.println("DTM: found java.home property " + foundFactory);
}
if (foundFactory != null)
{
return foundFactory;
}
}
}
catch (Exception ex)
{
if (debug)
{
ex.printStackTrace();
}
}
String serviceId = "META-INF/services/" + factoryId;
// try to find services in CLASSPATH
try
{
ClassLoader cl = DTMManager.class.getClassLoader();
InputStream is = null;
if (cl == null)
{
is = ClassLoader.getSystemResourceAsStream(serviceId);
}
else
{
is = cl.getResourceAsStream(serviceId);
}
if (is != null)
{
if (debug)
{
System.err.println("DTM: found " + serviceId);
}
BufferedReader rd = new BufferedReader(new InputStreamReader(is));
foundFactory = rd.readLine();
rd.close();
if (debug)
{
System.err.println("DTM: loaded from services: " + foundFactory);
}
if ((foundFactory != null) &&!"".equals(foundFactory))
{
return foundFactory;
}
}
}
catch (Exception ex)
{
if (debug)
{
ex.printStackTrace();
}
}
return defaultFactory;
}
/** %TBD% Doc */
public static final int IDENT_DTM_DEFAULT = 0xFFF00000;
/** %TBD% Doc */
public static final int IDENT_NODE_DEFAULT = 0x000FFFFF;
/**
* %TBD% Doc
*
* NEEDSDOC @param dtm
*
* NEEDSDOC ($objectName$) @return
*/
public abstract int getDTMIdentity(DTM dtm);
/**
* %TBD% Doc
*
* NEEDSDOC ($objectName$) @return
*/
public int getDTMIdentityMask()
{
return IDENT_DTM_DEFAULT;
}
/**
* %TBD% Doc
*
* NEEDSDOC ($objectName$) @return
*/
public int getNodeIdentityMask()
{
return IDENT_NODE_DEFAULT;
}
}