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package org.openslx.util;
import java.io.IOException;
import java.io.InputStream;
import java.io.StringWriter;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.transform.OutputKeys;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;
import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathConstants;
import javax.xml.xpath.XPathExpression;
import javax.xml.xpath.XPathExpressionException;
import javax.xml.xpath.XPathFactory;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.w3c.dom.Attr;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.xml.sax.SAXException;
public class XmlHelper
{
private final static Logger LOGGER = LogManager.getLogger( XmlHelper.class );
// TODO check thread-safety
private static final XPath XPath = XPathFactory.newInstance().newXPath();
private static DocumentBuilder dBuilder;
static {
DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance();
dbFactory.setNamespaceAware( true );
dbFactory.setIgnoringComments( true );
try {
dBuilder = dbFactory.newDocumentBuilder();
} catch ( ParserConfigurationException e ) {
LOGGER.error( "Failed to initalize DOM parser with default configurations." );
}
}
public static String globalXPathToLocalXPath( String xPath )
{
final StringBuilder exprBuilder = new StringBuilder();
final String[] elements = xPath.split( "/" );
for ( final String element : elements ) {
if ( !element.isEmpty() ) {
final Pattern arraySpecifierRegex = Pattern.compile( "^(.*)\\[(.*)\\]$" );
final Matcher arraySpecifierMatcher = arraySpecifierRegex.matcher( element );
final String elementName;
final String elementSpecifier;
if ( arraySpecifierMatcher.find() ) {
elementName = arraySpecifierMatcher.group( 1 );
elementSpecifier = arraySpecifierMatcher.group( 2 );
} else {
elementName = element;
elementSpecifier = null;
}
if ( !elementName.startsWith( "@" ) && !elementName.equals( "*" ) ) {
exprBuilder.append( "/*[local-name()='" + elementName + "']" );
} else {
exprBuilder.append( "/" + elementName );
}
if ( elementSpecifier != null && !elementSpecifier.isEmpty() ) {
exprBuilder.append( "[" + elementSpecifier + "]" );
}
}
}
return exprBuilder.toString();
}
public static XPathExpression compileXPath( String xPath ) throws XPathExpressionException
{
final String localXPath = XmlHelper.globalXPathToLocalXPath( xPath );
return XPath.compile( localXPath );
}
public static Document parseDocumentFromStream( InputStream is )
{
Document doc = null;
// read document from stream
try {
doc = dBuilder.parse( is );
} catch ( SAXException | IOException e ) {
doc = null;
}
// normalize parsed document
if ( doc != null ) {
doc.getDocumentElement().normalize();
}
return doc;
}
public static Document removeFormattingNodes( Document doc )
{
NodeList empty;
try {
empty = (NodeList)XPath.evaluate( "//text()[normalize-space(.) = '']",
doc, XPathConstants.NODESET );
} catch ( XPathExpressionException e ) {
LOGGER.error( "Bad XPath expression to find all empty text nodes." );
return null;
}
for ( int i = 0; i < empty.getLength(); i++ ) {
Node node = empty.item( i );
node.getParentNode().removeChild( node );
}
return doc;
}
public static String getUnformattedXml( InputStream is )
{
// prune empty text nodes, essentially removing all formatting
Document doc = parseDocumentFromStream( is );
return getXmlFromDocument( removeFormattingNodes( doc ), false );
}
public static String getFormattedXml( InputStream is )
{
Document doc = parseDocumentFromStream( is );
return getXmlFromDocument( doc, true );
}
public static String getXmlFromDocument( Document doc, boolean humanReadable )
{
try {
StringWriter writer = new StringWriter();
TransformerFactory tf = TransformerFactory.newInstance();
Transformer transformer = tf.newTransformer();
transformer.setOutputProperty( OutputKeys.OMIT_XML_DECLARATION, "no" );
transformer.setOutputProperty( OutputKeys.ENCODING, "UTF-8" );
transformer.setOutputProperty( OutputKeys.METHOD, "xml" );
if ( humanReadable ) {
transformer.setOutputProperty( OutputKeys.INDENT, "yes" );
transformer.setOutputProperty( "{http://xml.apache.org/xslt}indent-amount", "2" );
}
transformer.transform( new DOMSource( doc ), new StreamResult( writer ) );
return writer.toString();
} catch ( Exception ex ) {
LOGGER.error( "Failed to transform XML to String: ", ex );
return null;
}
}
public static Element getOrCreateElement( Document doc, Element parent, String nsUri, String nsName,
String name, String attrName, String attrValue )
{
final NodeList childList;
if ( nsUri == null ) {
childList = parent.getElementsByTagName( name );
} else {
childList = parent.getElementsByTagNameNS( nsUri, name );
}
Element element = null;
outer: for ( int i = 0; i < childList.getLength(); ++i ) {
Node n = childList.item( i );
if ( n.getNodeType() != Node.ELEMENT_NODE )
continue;
if ( attrName != null && attrValue != null ) {
for ( int ai = 0; ai < n.getAttributes().getLength(); ++ai ) {
Node attr = n.getAttributes().item( ai );
if ( attr.getNodeType() != Attr.ELEMENT_NODE )
continue;
Attr a = (Attr)attr;
if ( !attrName.equals( a.getLocalName() ) || !attrValue.equals( a.getValue() ) )
continue;
element = (Element)n;
break outer;
}
} else {
element = (Element)n;
break;
}
}
if ( element == null ) {
// Need a new <qemu:device alias="hostdev0">
if ( nsUri == null || nsName == null ) {
element = doc.createElement( name );
} else {
element = doc.createElementNS( nsUri, name );
element.setPrefix( nsName );
}
if ( attrName != null && attrValue != null ) {
element.setAttribute( attrName, attrValue );
}
parent.appendChild( element );
}
return element;
}
}
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