Receive notification of a processing instruction.
The Parser will invoke this method once for each processing instruction found: note that processing instructions may occur before or after the main document element.
A SAX parser should never report an XML declaration (XML 1.0, section 2.8) or a text declaration (XML 1.0, section 4.3.1) using this method.
@param target The processing instruction target.
@param data The processing instruction data, or null ifnone was supplied.
@exception org.xml.sax.SAXException Any SAX exception, possiblywrapping another exception.