Properties


	Setting Properties

If you have created a DOM document builder or a SAX parser using the JAXP interfaces, you may have difficulty setting features and properties directly using those interfaces. The following instructions tell you how to set properties on document builders and SAX parsers created from the JAXP interfaces.

The DocumentBuilderFactory interface contains a setAttribute(String,Object) method which may provide a means to set features and properties on the underyling parser. However, it cannot be relied upon. Therefore, you must use the Xerces DOMParser object directly. For example:

import org.apache.xerces.parsers.DOMParser;
import org.xml.sax.SAXException;
  
DOMParser parser = new DOMParser();

String id    = "http://apache.org/xml/properties/dom/document-class-name";
Object value = "org.apache.xerces.dom.DocumentImpl";
try {
    parser.setProperty(id, value);
} 
catch (SAXException e) {
    System.err.println("could not set parser feature");
}

Using the SAXParser interface in JAXP is better because you can query the underlying XMLReader implementation directly and that interface contains methods to set and query features and properties. For example:

import javax.xml.parsers.SAXParser;
import org.xml.sax.SAXException;
import org.xml.sax.XMLReader;

SAXParser parser = /* created from SAXParserFactory */;
XMLReader reader = parser.getXMLReader();

String id    = "http://apache.org/xml/properties/dom/document-class-name";
Object value = "org.apache.xerces.dom.DocumentImpl";
try {
    reader.setProperty(id, value);
} 
catch (SAXException e) {
    System.err.println("could not set parser feature");
}


	General Properties


	http://xml.org/sax/properties/xml-string

Desc:	Get the string of characters associated with the current event. If the parser recognizes and supports this property but is not currently parsing text, it should return null.
Type:	java.lang.String
Access:	read-only
Note:	This property is currently not supported because the contents of the XML string returned by this property is not well defined.


	http://apache.org/xml/properties/schema/external-schemaLocation

Desc:	The XML Schema Recommendation explicitly states that the inclusion of schemaLocation/noNamespaceSchemaLocation attributes is only a hint; it does not mandate that these attributes must be used to locate schemas. Similar situation happens to <import> element in schema documents. This property allows the user to specify a list of schemas to use. If the targetNamespace of a schema (specified using this property) matches the targetNamespace of a schema occurring in the instance document in schemaLocation attribute, or if the targetNamespace matches the namespace attribute of <import> element, the schema specified by the user using this property will be used (i.e., the schemaLocation attribute in the instance document or on the <import> element will be effectively ignored).
Type:	java.lang.String
Access:	read-write
Note:	The syntax is the same as for schemaLocation attributes in instance documents: e.g, "http://www.example.com file_name.xsd". The user can specify more than one XML Schema in the list.


	http://apache.org/xml/properties/schema/external-noNamespaceSchemaLocation

Desc:	This property allows the user to specify an XML Schema with no namespace.
Type:	java.lang.String
Access:	read-write
Note:	The syntax is a same as for the noNamespaceSchemaLocation attribute that may occur in an instance document: e.g."file_name.xsd". The user may specify only one XML Schema. For more information see the documentation for the http://apache.org/xml/properties/schema/external-schemaLocation property.


	http://apache.org/xml/properties/input-buffer-size

Desc:	The size of the input buffer in the readers. This determines how many bytes to read for each chunk.
Type:	java.lang.Integer
Access:	read-write
Note:	Some tests indicate that a bigger buffer size can improve the parsing performance for relatively large files. The default buffer size in Xerces is 2K. This would give a good performance for small documents (less than 10K). For documents larger than 10K, specifying the buffer size to 4K or 8K will significantly improve the performance. But it's not recommended to set it to a value larger than 16K. For really tiny documents (1K, for example), you can also set it to a value less than 2K, to get the best performance.


	DOM Properties


	http://apache.org/xml/properties/dom/current-element-node

Desc:	The current DOM element node while parsing.
Type:	org.w3c.dom.Element
Access:	read-only
Note:	This property is useful for determining the location with a DOM document when an error occurs.


	http://apache.org/xml/properties/dom/document-class-name

Desc:	The fully qualified name of the class implementing the org.w3c.dom.Document interface. The implementation used must have a zero argument constructor.
Type:	java.lang.String
Default:	"org.apache.xerces.dom.DocumentImpl"
Access:	read-write
Note:	When the document class name is set to a value other than the name of the default document factory, the deferred node expansion feature does not work.


	SAX Properties


	http://xml.org/sax/properties/declaration-handler

Desc:	Set the handler for DTD declarations.
Type:	org.xml.sax.ext.DeclHandler
Access:	read-write


	http://xml.org/sax/properties/lexical-handler

Desc:	Set the handler for lexical parsing events.
Type:	org.xml.sax.ext.LexicalHandler
Access:	read-write


	http://xml.org/sax/properties/dom-node

Desc:	The DOM node currently being visited, if SAX is being used as a DOM iterator. If the parser recognizes and supports this property but is not currently visiting a DOM node, it should return null.
Type:	org.w3c.dom.Node
Access:	(parsing) read-only; (not parsing) read-write;
Note:	This property is only for SAX parser implementations used as DOM tree walkers. Currently, Xerces does not have this functionality.