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// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.searchlib.gbdt;
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;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import java.io.ByteArrayInputStream;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.nio.charset.Charset;
import java.util.LinkedList;
import java.util.List;
import java.util.Optional;
/**
* @author Simon Thoresen Hult
*/
abstract class XmlHelper {
private static final Charset UTF8 = Charset.forName("UTF-8");
public static Element parseXml(String xml)
throws ParserConfigurationException, IOException, SAXException
{
return parseXmlStream(new ByteArrayInputStream(xml.getBytes(UTF8)));
}
public static Element parseXmlFile(String fileName)
throws ParserConfigurationException, IOException, SAXException
{
return parseXmlStream(new FileInputStream(fileName));
}
public static Element parseXmlStream(InputStream in)
throws ParserConfigurationException, IOException, SAXException
{
DocumentBuilderFactory factory = createDocumentBuilderFactory();
DocumentBuilder builder = factory.newDocumentBuilder();
Document doc = builder.parse(in);
return doc.getDocumentElement();
}
private static DocumentBuilderFactory createDocumentBuilderFactory() throws ParserConfigurationException {
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
factory.setNamespaceAware(true);
factory.setXIncludeAware(false);
// XXE prevention
factory.setFeature("http://xml.org/sax/features/external-general-entities", false);
factory.setFeature("http://xml.org/sax/features/external-parameter-entities", false);
factory.setFeature("http://apache.org/xml/features/nonvalidating/load-external-dtd", false);
return factory;
}
public static String getAttributeText(Node node, String name) {
Node valueNode = node.getAttributes().getNamedItem(name);
if (valueNode == null) {
throw new IllegalArgumentException("Missing '" + name + "' attribute in element '" +
node.getNodeName() + "'.");
}
String valueText = valueNode.getTextContent();
if (valueText == null || valueText.isEmpty()) {
throw new IllegalArgumentException("Attribute '" + name + "' in element '" +
node.getNodeName() + "' is empty.");
}
return valueText;
}
public static String getAttributeTextOrNull(Node node, String name) {
Node valueNode = node.getAttributes().getNamedItem(name);
if (valueNode == null) return null;
return valueNode.getTextContent();
}
public static Optional<String> getOptionalAttributeText(Node node, String name) {
Node valueNode = node.getAttributes().getNamedItem(name);
if (valueNode == null) return Optional.empty();
return Optional.of(valueNode.getTextContent());
}
public static Element getSingleElement(Node node, String name) {
List<Element> children = getChildElements(node, name);
if (children.isEmpty()) {
if (name != null) {
throw new IllegalArgumentException("Node '" + node.getNodeName() + "' has no '" + name + "' children.");
} else {
throw new IllegalArgumentException("Node '" + node.getNodeName() + "' has no children.");
}
}
if (children.size() != 1) {
if (name != null) {
throw new IllegalArgumentException("Expected 1 '" + name + "' child, got " + children.size() + ".");
} else {
throw new IllegalArgumentException("Expected 1 child, got " + children.size() + ".");
}
}
return children.get(0);
}
public static List<Element> getChildElements(Node node, String name) {
NodeList children = node.getChildNodes();
List<Element> lst = new LinkedList<>();
for (int i = 0, len = children.getLength(); i < len; ++i) {
Node child = children.item(i);
if (!(child instanceof Element)) {
continue;
}
if (name != null && !child.getNodeName().equalsIgnoreCase(name)) {
continue;
}
lst.add((Element)child);
}
return lst;
}
}
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