Changing the Underlying Implementation of XML Parsing

Changing the Underlying Implementation
A JAXP implementation comes with a default parser, transformer, xpath engine, and a schema validator, but, as mentioned earlier, JAXP is a pluggable API, and we can plug in any JAXP complaint processor to change the defaults. To do that we must set the appropriate javax.xml.xxx.yyyFactory property pointing to the fully qualified class name of the new yyyFactory. Then, when yyyFactory.newInstance() is invoked, JAXP uses the following ordered lookup procedure to determine the implementation class to load:

1. Use the javax.xml.xxx.yyyFactory system property.


2. Use the properties file "lib/jaxp.properties" in the JRE directory. The jaxp.properties file is read only once by the JAXP 1.3 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.


3. Use the Services API (as detailed in the JAR specification), if available, to determine the classname. The Services API will look for the classname in the file META-INF/services/javax.xml.xxx.yyyFactory in jars available to the runtime.


4. Use the platform default javax.xml.xxx.yyyFactory instance

where javax.xml.xxx.yyyFactory can be one of the following:

javax.xml.parsers.SAXParserFactory
javax.xml.parsers.DocumentBuilderFactory
javax.xml.transform.TransformerFactory
javax.xml.xpath.XPathFactory
javax.xml.validation.SchemaFactory:schemaLanguage (schemaLanguage is the parameter passed to the newInstance method of SchemaFactory)

Extract From XML Transformation Using the TrAX APIs in JAXP