public static Element parseWithCRC(InputStream inputStream)
throws XMLStreamException, CRCMismatchException {
XMLInputFactory xif = XMLInputFactory.newFactory();
Element element = parse(xif.createXMLStreamReader(inputStream));
checkCRC(element);
element.removeChildren(CRC_ELEMENT);
return element;
}
private static void checkCRC(Element element) throws CRCMismatchException {
Element CRCElement = element.getChild(CRC_ELEMENT);
if (CRCElement != null) {
String crc = CRCElement.getText();
// the length in bytes is the number of characters divided by 2
int crcLength = crc.length() / 2;
if (!crc.equals(element.getHash(crcLength, CRC_ELEMENT))) {
throw new CRCMismatchException();
}
}
}
// public static void write(OutputStream stream, Element element, int hashLength) throws
// XMLStreamException {
// XMLOutputFactory xof = XMLOutputFactory.newInstance();
// IndentingXMLStreamWriter xtw = new
// IndentingXMLStreamWriter(xof.createXMLStreamWriter(stream));
// writeXMLStreamWriter(xtw, element, hashLength);
// }
//
private static void writeXMLStreamWriter(XMLStreamWriter xtw, Element element, int hashLength)
throws XMLStreamException {
if (hashLength > 0) {
String hash = element.getHash(hashLength);
Element hashElement = new Element(CRC_ELEMENT);
hashElement.setText(hash);
element.addChild(hashElement);
}
writeElement(xtw, element);
xtw.writeEndDocument();
xtw.flush();
xtw.close();
if (hashLength > 0) {
element.removeChildren(CRC_ELEMENT);
}
}
private static Element parseElement(XMLStreamReader xsr) throws XMLStreamException {
// xsr points to a START_ELEMENT event. Create the element and read all its attributes
// Then read all its children events
Element element = new Element(xsr.getLocalName());
// text that will be added to the element. Text can come in different events, so we add it here
// and add it to the element at the end
StringBuilder elementText = new StringBuilder();
int attributeCount = xsr.getAttributeCount();
for (int i = 0; i < attributeCount; i++) {
element.putAttribute(xsr.getAttributeLocalName(i), xsr.getAttributeValue(i));
}
while (xsr.hasNext()) {
xsr.next();
if (xsr.getEventType() == XMLStreamConstants.END_ELEMENT) {
// element is closed. Move the cursor and return it
// check if there is some text to add before (empty text is not added, but added text is not
// trimmed)
// we set empty text also if the element has no children
if (!elementText.toString().trim().isEmpty() || !element.hasChildren()) {
element.setText(elementText.toString());
}
// xsr.next();
return element;
} else if (xsr.getEventType() == XMLStreamConstants.CHARACTERS) {
// an attribute of the current element
elementText.append(xsr.getText());
} else if (xsr.getEventType() == XMLStreamConstants.START_ELEMENT) {
// new element begins -> read it recursively and add it to the current element
element.addChild(parseElement(xsr));
}
}
// we reached the end of the document without the tag end -> error parsing
throw new XMLStreamException(
"End of the document unexpectedly reached. Element " + element.getName() + " not closed");
}
private static void writeElement(XMLStreamWriter xtw, Element element) throws XMLStreamException {
xtw.writeStartElement(element.getName());
for (String attributeName : element.getAttributeNames()) {
xtw.writeAttribute(attributeName, element.getAttributeValue(attributeName));
}
if (element.hasText()) {
xtw.writeCharacters(element.getText());
} else {
for (Element child : element.getChildren()) {
writeElement(xtw, child);
}
}
xtw.writeEndElement();
}