org.hibernate.validator.internal.xml.AbstractStaxBuilder Maven / Gradle / Ivy
/*
* Hibernate Validator, declare and validate application constraints
*
* License: Apache License, Version 2.0
* See the license.txt file in the root directory or .
*/
package org.hibernate.validator.internal.xml;
import java.util.Optional;
import javax.xml.namespace.QName;
import javax.xml.stream.XMLEventReader;
import javax.xml.stream.XMLStreamException;
import javax.xml.stream.events.Attribute;
import javax.xml.stream.events.StartElement;
import javax.xml.stream.events.XMLEvent;
/**
* Other Stax xml builders should extend from this one.
* Provides some common functionality like reading an attribute value
* or value of a simple tag.
*
* @author Marko Bekhta
*/
public abstract class AbstractStaxBuilder {
protected abstract String getAcceptableQName();
/**
* Checks if the given {@link XMLEvent} is a {@link StartElement} and if the
* corresponding xml tag can be processed based on a tag name.
*
* @param xmlEvent an event to check
*
* @return {@code true} if corresponding event can be processed by current builder,
* {@code false} otherwise
*/
protected boolean accept(XMLEvent xmlEvent) {
return xmlEvent.isStartElement() && xmlEvent.asStartElement().getName().getLocalPart().equals( getAcceptableQName() );
}
public boolean process(XMLEventReader xmlEventReader, XMLEvent xmlEvent) {
if ( accept( xmlEvent ) ) {
try {
add( xmlEventReader, xmlEvent );
}
catch (XMLStreamException e) {
throw new IllegalStateException( e );
}
return true;
}
return false;
}
protected abstract void add(XMLEventReader xmlEventReader, XMLEvent xmlEvent) throws XMLStreamException;
/**
* Reads a value between a simple tag element. In case of a {@code some-value } will
* return {@code some-value} as a string.
*
* @param xmlEventReader a current {@link XMLEventReader}
*
* @return a value of a current xml tag as a string
*/
protected String readSingleElement(XMLEventReader xmlEventReader) throws XMLStreamException {
// trimming the string value as it might contain leading/trailing spaces or \n
XMLEvent xmlEvent = xmlEventReader.nextEvent();
StringBuilder stringBuilder = new StringBuilder( xmlEvent.asCharacters().getData() );
while ( xmlEventReader.peek().isCharacters() ) {
xmlEvent = xmlEventReader.nextEvent();
stringBuilder.append( xmlEvent.asCharacters().getData() );
}
return stringBuilder.toString().trim();
}
/**
* Reads a value of an attribute of a given element.
*
* @param startElement an element to get an attribute from
* @param qName a {@link QName} of an attribute to read
*
* @return a value of an attribute if it is present, {@link Optional#empty()} otherwise
*/
protected Optional readAttribute(StartElement startElement, QName qName) {
Attribute attribute = startElement.getAttributeByName( qName );
return Optional.ofNullable( attribute ).map( Attribute::getValue );
}
}