Develop Reference

Parsing an XML with 2 default namespace in Java using DOM parser

Thanks in advance.
I have a xml with 2 default namespace at rootlevel and then as element level.
<?xml version="1.0" encoding="UTF-8"?>
<Msg xmlns="http://www.geological.com">
<header>
<date>08-08-2021</date>
<jur>US</jur>
</header>
<Demographic xmlns="urn:com.test:009">
<geoData>
<id>DL89716</id>
<name>North</name>
</geoData>
</Demographic>
</Msg>
I am using Java DOM parser to read this xml and fetch value of "id".
Still I am getting value as null
DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance();
DocumentBuilder dBuilder = dbFactory.newDocumentBuilder();
dbFactory.setNamespaceAware(true);
document = dBuilder.parse(new InputSource(new StringReader(xmlPayLoad)));
document.normalize();
XPathEvaluator xPathObj = (XPathEvaluator)XPathFactory.newInstance(NamespaceConstant.OBJECT_MODEL_SAXON).newXPath();
xPathObj.setNamespaceContext(new MyNameSpace());
xPathObj.getStaticContext().setDefaultElementNamespace("http://www.geological.com");
XPathExpression expr = xPathObj.compile(xpath);
Object result = expr.evaluate(document, XPathConstants.NODESET);
NodeList nodeList = (NodeList) result;
private static class MyNameSpace implements NamespaceContext {
//The lookup for the namespace uris is delegated to the stored document.
public String getNamespaceURI(String prefix) {
if (prefix.equals(XMLConstants.DEFAULT_NS_PREFIX)) {
return null;
} if("ns".equals(prefix)){
return "urn:com.test:009";
}
}
public String getPrefix(String namespaceURI) {
return sourceDocument.lookupPrefix(namespaceURI);
}
#SuppressWarnings("rawtypes")
public Iterator getPrefixes(String namespaceURI) {
return null;
}
}

Here is a fully functional example:
import org.w3c.dom.Document;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
import javax.xml.XMLConstants;
import javax.xml.namespace.NamespaceContext;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
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 java.io.IOException;
import java.io.StringReader;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
public class NamespacesExample {
private static String xmlPayLoad =
"<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n" +
"<Msg xmlns=\"http://www.geological.com\">\n" +
" <header>\n" +
" <date>08-08-2021</date>\n" +
" <jur>US</jur>\n" +
" </header>\n" +
" <Demographic xmlns=\"urn:com.test:009\">\n" +
" <geoData>\n" +
" <id>DL89716</id>\n" +
" <name>North</name>\n" +
" </geoData>\n" +
" </Demographic>\n" +
"</Msg>";
public static void main(String[] args) {
try {
DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance();
DocumentBuilder dBuilder = null;
dbFactory.setNamespaceAware(true);
dBuilder = dbFactory.newDocumentBuilder();
Document document = dBuilder.parse(new InputSource(new StringReader(xmlPayLoad)));
final Map<String, String> ns = new HashMap<>();
ns.put("geo", "http://www.geological.com");
ns.put("test", "urn:com.test:009");
XPath xpath = XPathFactory.newInstance().newXPath();
xpath.setNamespaceContext(new MyNameSpace(ns));
XPathExpression expr = xpath.compile("/geo:Msg/test:Demographic/test:geoData/test:id/text()");
String result = (String) expr.evaluate(document, XPathConstants.STRING);
System.out.println("Result: " + result);
} catch (ParserConfigurationException | IOException | XPathExpressionException | SAXException e) {
e.printStackTrace();
}
}
private static class MyNameSpace implements NamespaceContext {
private final Map<String, String> ns;
MyNameSpace(Map<String, String> ns) {
this.ns = new HashMap<>(ns);
this.ns.put(XMLConstants.XML_NS_PREFIX, XMLConstants.XML_NS_URI);
this.ns.put(XMLConstants.XMLNS_ATTRIBUTE, XMLConstants.XMLNS_ATTRIBUTE_NS_URI);
}
#Override
public String getNamespaceURI(String prefix) {
if(prefix == null) {
throw new IllegalArgumentException();
}
final String uri = ns.get(prefix);
return uri == null ? XMLConstants.NULL_NS_URI : uri;
}
#Override
public String getPrefix(String namespaceURI) {
throw new UnsupportedOperationException();
}
#Override
public Iterator getPrefixes(String namespaceURI) {
throw new UnsupportedOperationException();
}
}
}
Some remarks:
The order of these statements is significant. Otherwise there is no namespace awareness:
dbFactory.setNamespaceAware(true);
dBuilder = dbFactory.newDocumentBuilder();
Why do you use XPathEvaluator? There is no need for that. Using the interface XPath is enough.
What is NamespaceConstant.OBJECT_MODEL_SAXON? At least in this example, we don't need it.
With my generic NamespaceContext implementation you can use a simple Map<String, String> to define the namespace prefixes for XPATH evaluation.
Dedicated prefixes should be used for each namespace used in the XML, regardless of how the namespace is declared in the XML document.
Then you can use this XPATH expression to extract the id: /geo:Msg/test:Demographic/test:geoData/test:id/text()
Output is:
Result: DL89716

I would use //*:id as the path if you know there is a single id element you are looking for, or at least there are not several id elements from different namespaces and you want to select only those from one namespace.
If you only want to select those from one namespace (e.g. urn:com.test:009) then set that as the default namespace and you can simply use //id or //Demographic/geoData/id.
Only if you really need to select elements from different namespaces you need to bind prefixes.
With the Java 8 built-in JAXP XPathFactory and a not namespace aware DocumentBuilderFactory the following also works for me to select the id element node as then the default namespace declarations are ignored when building the DOM tree:
DocumentBuilderFactory documentBuilderFactory = DocumentBuilderFactory.newInstance();
documentBuilderFactory.setNamespaceAware(false);
DocumentBuilder jaxpDocumentBuilder = documentBuilderFactory.newDocumentBuilder();
Document domDoc = jaxpDocumentBuilder.parse(new File("sample1.xml"));
XPathFactory jaxpXPathFactory = XPathFactory.newInstance();
Node resultDomNode = (Node)jaxpXPathFactory.newXPath().evaluate("/Msg/Demographic/geoData/id", domDoc, XPathConstants.NODE);
I think in your original code, once you build a namespace aware DOM, with your use of the Saxon API, you could get away with setting
xPathObj.getStaticContext().setUnprefixedElementMatchingPolicy(UnprefixedElementMatchingPolicy.ANY_NAMESPACE);
and not to set up any namespace context nor default element namespace.
The other way with Saxon 10 and XPath to match elements in any namespace with selectors like id I could find is to dive into its low-level API to mix it with the s9api:
Processor processor = new Processor(false);
DocumentBuilder docBuilder = processor.newDocumentBuilder();
XdmNode input = docBuilder.build(new File("sample1.xml"));
NodeInfo contextItem = input.getUnderlyingNode();
XPathEvaluator xpathEvaluator = new XPathEvaluator(processor.getUnderlyingConfiguration());
IndependentContext independentContext = new IndependentContext();
independentContext.setUnprefixedElementMatchingPolicy(UnprefixedElementMatchingPolicy.ANY_NAMESPACE);
xpathEvaluator.setStaticContext(independentContext);
XPathExpression expression = xpathEvaluator.createExpression("/Msg/Demographic/geoData/id");
NodeInfo resultInfo = (NodeInfo) expression.evaluateSingle(expression.createDynamicContext(contextItem));
XdmNode resultNode = new XdmNode(resultInfo);
System.out.println(resultNode);

Checking if particular node exists in Xml file using Xpath

I would like to check is code = "ABC" exists in my xml file using xPath.Can you please suggest me some methods for it?
<metadata>
<codes class = "class1">
<code code = "ABC">
<detail "blah blah"/>
</code>
</codes>
<codes class = "class2">
<code code = "123">
<detail "blah blah"/>
</code>
</codes>
</metadata>
[EDIT]
I did following. It reuturns null.
XPath xPath = XPathFactory.newInstance().newXPath();
XPathExpression expr = xPath.compile("//codes/code[# code ='ABC']");
Object result = expr.evaluate(doc, XPathConstants.NODESET);
NodeList nodes = (NodeList) result;
for (int i = 0; i < nodes.getLength(); i++) {
System.out.println("nodes: "+ nodes.item(i).getNodeValue());
}

I don't know how you tested your code because <detail "blah blah"/> is an incorrect xml construct it should be <detail x="blah blah"/> i.e. a name-value pair !!
For the XPath Expression "//codes/code[# code ='ABC']" the nodes.item(i).getNodeValue()) is going to be null because it will return an Element. See the below Javadoc comment:
A working sample:
import java.io.ByteArrayInputStream;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathConstants;
import javax.xml.xpath.XPathExpression;
import javax.xml.xpath.XPathFactory;
import org.w3c.dom.Document;
import org.w3c.dom.NodeList;
public class Test
{
public static void main(String[] args) throws Exception
{
Document doc = getDoc();
XPath xPath = XPathFactory.newInstance().newXPath();
XPathExpression expr = xPath.compile("//codes/code[#code ='ABC']");
Object result = expr.evaluate(doc, XPathConstants.NODESET);
NodeList nodes = (NodeList) result;
System.out.println("Have I found anything? " + (nodes.getLength() > 0 ? "Yes": "No"));
for (int i = 0; i < nodes.getLength(); i++) {
System.out.println("nodes: "+ nodes.item(i).getNodeValue());
}
}
private static Document getDoc()
{
String xml = "<metadata>"+
"<codes class = 'class1'>"+
"<code code='ABC'>"+
"<detail x='blah blah'/>"+
"</code>"+
"</codes>"+
"<codes class = 'class2'>"+
"<code code = '123'>"+
"<detail x='blah blah'/>"+
"</code>"+
"</codes>"+
"</metadata>";
DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
try {
DocumentBuilder db = dbf.newDocumentBuilder();
Document dom = db.parse(new ByteArrayInputStream(xml.getBytes()));
return dom;
}catch(Exception pce) {
pce.printStackTrace();
}
return null;
}
}

Java DOM: cannot write adapted XML to file

I have the following simplified XML:
<?xml version="1.0" encoding="UTF-8"?>
<ExportData>
<Rows>
<R>
<companyCodestringtrue>101</companyCodestringtrue>
<transactionQualifierstring>Sales</transactionQualifierstring>
<menuItemNumberlong>4302150</menuItemNumberlong>
<productQuantityinttrue>14</productQuantityinttrue>
<productValueInclVATdecimaltrue>1.90</productValueInclVATdecimaltrue>
<productValueExclVATdecimaltrue>1.775701</productValueExclVATdecimaltrue>
</R>
<R>
<companyCodestringtrue>101</companyCodestringtrue>
<transactionQualifierstring>Sales</transactionQualifierstring>
<menuItemNumberlong>333555</menuItemNumberlong>
<productQuantityinttrue>0</productQuantityinttrue>
<productValueInclVATdecimaltrue>3.90</productValueInclVATdecimaltrue>
<productValueExclVATdecimaltrue>3.775701</productValueExclVATdecimaltrue>
</R>
<R>
<companyCodestringtrue>101</companyCodestringtrue>
<transactionQualifierstring>Sales</transactionQualifierstring>
<menuItemNumberlong>1235665</menuItemNumberlong>
<productQuantityinttrue>5</productQuantityinttrue>
<productValueInclVATdecimaltrue>4.90</productValueInclVATdecimaltrue>
<productValueExclVATdecimaltrue>4.775701</productValueExclVATdecimaltrue>
</R>
</Rows>
</ExportData>
I need to delete each complete <R> element if the <productQuantityinttrue> element equals "0".
I came up with the following Java code:
package filterPositions;
import java.io.File;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.transform.Result;
import javax.xml.transform.Source;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerConfigurationException;
import javax.xml.transform.TransformerException;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
public class FilterPositions {
public static String result = "";
public static void main(String[] args) throws Exception {
try {
DocumentBuilderFactory docFactory = DocumentBuilderFactory.newInstance();
DocumentBuilder docBuilder = docFactory.newDocumentBuilder();
File filePath = new File("C:/LSA_SALES_EXPORT_1507_test_zero_qu.xml");
Document doc = docBuilder.parse(filePath);
Node rootNode = doc.getDocumentElement();
final Element element = doc.getDocumentElement();
// output new XML Document
DocumentBuilder parser = docFactory.newDocumentBuilder();
Document newdoc = parser.newDocument();
newdoc.adoptNode(traversingXML(element));
writeXmlFile(newdoc, "LSA_SALES_EXPORT_1507_test_zero_qu_OUT.xml");
System.out.println("Done...");
System.out.println("Exiting...");
} catch (Exception e) {
e.printStackTrace();
}
}
public static Element traversingXML(Element element) {
NodeList positionen = element.getElementsByTagName("R");
Element e = null;
for (int i = 0; i < positionen.getLength(); i++) {
e = (Element) positionen.item(i);
for (Node child = e.getFirstChild(); child != null; child = child.getNextSibling()) {
if (child instanceof Element && "productQuantityinttrue".equals(child.getNodeName())&& "0".equals(child.getTextContent())) {
e.getParentNode().removeChild(e);
}
}
}
System.out.println(e);
return e;
}
public static void writeXmlFile(Document doc, String filename) {
try {
// Prepare the DOM document for writing
Source source = new DOMSource();
// Prepare the output file
File file = new File(filename);
Result result = new StreamResult(file);
// Write the DOM document to the file
Transformer xformer = TransformerFactory.newInstance()
.newTransformer();
xformer.transform(source, result);
} catch (TransformerConfigurationException e) {
} catch (TransformerException e) {
}
}
}
I am not sure if my method "traversingXML" is working properly. My problem right now is that the adapted XML structure (one deleted) is not written to newdoc.

You don't copy the original document to newdoc; instead you create a new, empty XML document.
Instead, try this code:
...
final Element element = doc.getDocumentElement(); // original code up to here
traversingXML(element); // delete the node
writeXmlFile(doc, "LSA_SALES_EXPORT_1507_test_zero_qu_OUT.xml"); // save modified document

error: java.lang.String cannot be cast to org.w3c.dom.Node

I am trying to parse xml string and I am getting java.lang.String cannot be cast to org.w3c.dom.Node error.
This is the code I am using:
XPathFactory xPathFactory = XPathFactory.newInstance();
XPath xPath = xPathFactory.newXPath();
String expression = "//Home/ListOfCustomers";
XPathExpression xPathExpression = xPath.compile(expression);
Object nl = xPathExpression.evaluate(xmlResp);
This is how the XML string is constructed:
<?xml version="1.0" encoding="ISO-8859-1"?>
<Home>
<ListOfCustomers type="Regular" count="939">
<Customer>
<CustName>xyz</CustName>
</Customer>
<Customer>
<CustName>abc</CustName>
</Customer>
<Customer>
<CustName>def</CustName>
</Customer>
</ListOfCustomers>
</Home>
What am I missing here?

Object nl = xPathExpression.evaluate(xmlResp);
This is the issue here. With a single argument to the evaluate method, it expect either variable of type InputSource or Object, have you declare xmlResp to either of it? Also, both of these methods return of type String, so why are you assign to a variable of type Object?
Since you have the xml file, why don't you initialize your xmlResp to type of InputSource? Then use the xPathExpression evaluate on the inputsource? Something like the following.
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.InputStreamReader;
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.w3c.dom.NodeList;
import org.xml.sax.InputSource;
public class XMLParser
{
/**
* #param args
*/
public static void main(String[] args)
{
try {
XPathFactory xPathFactory = XPathFactory.newInstance();
XPath xPath = xPathFactory.newXPath();
InputSource doc = new InputSource(new InputStreamReader(new FileInputStream(new File("file.xml"))));
String expression = "//Home/ListOfCustomers";
XPathExpression xPathExpression = xPath.compile(expression);
NodeList elem1List = (NodeList) xPathExpression.evaluate(doc, XPathConstants.NODESET);
xPathExpression = xPath.compile("#type");
for (int i = 0; i < elem1List.getLength(); i++)
{
System.out.println(xPathExpression.evaluate(elem1List.item(i), XPathConstants.STRING));
}
}
catch (XPathExpressionException e)
{
// TODO Auto-generated catch block
e.printStackTrace();
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}

Just having a quick look at the docs:
http://docs.oracle.com/javase/1.5.0/docs/api/javax/xml/xpath/XPathExpression.html#evaluate(java.lang.Object)
Then the api defines this for compile:
item - The starting context (node or node list, for example).
So assuming this is the method you are using, it looks like you need to send in a node - or node list, not just a String.

Why is this java code not parsing my Xml correctly?

I've written class to parse some xml into an object and it's not working correctly, when I try and get the value of a node I get a null rather than the contents of the node.
Here is a simplified version of my class that just does the xml parsing of a single node:
import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import org.apache.log4j.Logger;
import org.apache.log4j.xml.DOMConfigurator;
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 XmlReaderCutDown {
private static Logger logger = Logger.getLogger(CtiButtonsXmlReader.class);
public static void testXml(String confFile){
DocumentBuilderFactory docBuilderFactory = DocumentBuilderFactory.newInstance();
try {
DocumentBuilder docBuilder = docBuilderFactory.newDocumentBuilder();
Document doc = docBuilder.parse(new File(confFile));
doc.getDocumentElement().normalize();
if (logger.isDebugEnabled()){
logger.debug("The root element is " + doc.getDocumentElement().getNodeName());
}
NodeList rows = doc.getElementsByTagName("row");
NodeList topRowButtons = ((Element)rows.item(0)).getElementsByTagName("button");
logger.debug("Top row has " +topRowButtons.getLength() + " items.");
Node buttonNode = topRowButtons.item(0);
NodeList nodeList = ((Element)buttonNode).getElementsByTagName("id");
logger.debug("Node list count for "+ "id" + " = " + nodeList.getLength());
Element element = (Element)nodeList.item(0);
String xx = element.getNodeValue();
logger.debug(xx);
String elementValue = ((Node)element).getNodeValue();
if (elementValue != null) {
elementValue = elementValue.trim();
}
else {
logger.debug("Value was null");
}
logger.debug("Node id = "+ elementValue);
} catch (ParserConfigurationException e) {
logger.fatal(e.toString(),e);
} catch (SAXException e) {
logger.fatal(e.toString(),e);
} catch (IOException e) {
logger.fatal(e.toString(),e);
} catch (Exception e) {
logger.fatal(e.toString(),e);
}
}
public static void main(String[] args){
DOMConfigurator.configure("log4j.xml");
testXml("test.xml");
}
}
And here is a stripped down version of my xml file:
<?xml version="1.0"?>
<root>
<row>
<button>
<id>this is an id</id>
<action>action</action>
<image-src>../images/img.png</image-src>
<alt-text>alt txt</alt-text>
<tool-tip>Tool tip</tool-tip>
</button>
</row>
</root>
This is what the logging statments output:
DEBUG XmlReaderCutDown - The root element is root
DEBUG XmlReaderCutDown - Top row has 1 items.
DEBUG XmlReaderCutDown - Node list count for id = 1
DEBUG XmlReaderCutDown -
DEBUG XmlReaderCutDown - Value was null
DEBUG XmlReaderCutDown - Node id = null
Why isn't it getting the text in the xml node?
I'm running using JDK 1.6_10

Because the element you get is the parent element of the text one, containing the text you need. To access the text of this element, you shall use getTextContent instead of getNodeValue.
For more information, see the table in the Node javadoc.

See http://java.sun.com/j2se/1.5.0/docs/api/org/w3c/dom/Node.html . Element.getNodeValue() always returns null. You should use Element.getTextContent()

Consider using XPath as an alternative to manually walking nodes:
public static void testXml(String confFile)
throws XPathExpressionException {
XPathFactory xpFactory = XPathFactory.newInstance();
XPath xpath = xpFactory.newXPath();
NodeList rows = (NodeList) xpath.evaluate("root/row",
new InputSource(confFile), XPathConstants.NODESET);
for (int i = 0; i < rows.getLength(); i++) {
Node row = rows.item(i);
String id = xpath.evaluate("button/id", row);
System.out.println("id=" + id);
}
}
public static void main(String[] args)
throws XPathExpressionException {
testXml("test.xml");
}