Java and XML: Read XML tags with or without namespace

Question

We are trying to build a service that receive some XML files. But people send it, sometimes use namespaces, sometimes not. For example:

<?xml version="1.0" encoding="UTF-8"?>
<ds:EnvioDoc version="1.0" xmlns:ds="http://my.domain">
  <ds:Cabecera version="1.0">
    <ds:IdRec>215217190015</ds:IdRec>
    <ds:IdEm>211003420017</ds:IdEm>
    <ds:IdDoc>2995019</ds:IdDoc>
  </ds:Cabecera>
 <Cuerpo>
  <CorpDoc version="1.0" xmlns="http://my.domain"     xmlns:xd="http://www.w3.org/2000/09/xmldsig#">
  <body>
    <Fecha>2016-08-12T00:11:50-03:00</Fecha>
[..]

or can come like:

<?xml version="1.0" encoding="UTF-8"?>
<EnvioDoc version="1.0" xmlns="http://my.domain">
  <Cabecera version="1.0">
    <IdRec>215217190015</IdRec>
    <IdEm>211003420017</IdEm>
    <IdDoc>2995019</IdDoc>
  </Cabecera>
  <Cuerpo>
   <CorpDoc version="1.0" xmlns="http://my.domain"  xmlns:xd="http://www.w3.org/2000/09/xmldsig#">
    <body>
      <Fecha>2016-08-12T00:11:50-03:00</Fecha>
 [..]

We have tried to use this code to read this files:

        File edocFile = new File(fileName);
        DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance();
        DocumentBuilder dBuilder = dbFactory.newDocumentBuilder();
        Document doc = dBuilder.parse(edocFile);

        //recomendado http://stackoverflow.com/questions/13786607/normalization-in-dom-parsing-with-java-how-does-it-work
        doc.getDocumentElement().normalize();
    NodeList nlCabecera = doc.getElementsByTagNameNS("*","Cabecera");
    Node cabeceraNode = nlCabecera .item(0);
    if (cabeceraNode.getNodeType() == Node.ELEMENT_NODE) {

But getting a NullPointerExsception in the if line.

Any suggest?

TIA

If you want to work with namespaces then I would start with setting dbFactory.setNamespaceAware(true);. — Martin Honnen
– Martin Honnen, Commented Aug 18, 2016 at 15:13
Note also that both your samples use the same namespace, only as a default namespace in the second sample and with a prefix in the first. — Martin Honnen
– Martin Honnen, Commented Aug 18, 2016 at 15:14
I have put the suggestion into an answer so that you can mark the problem as solved. — Martin Honnen
– Martin Honnen, Commented Aug 18, 2016 at 15:53

Martin Honnen · Accepted Answer · 2016-08-18 15:49:58Z

3

To use namespace aware DOM methods like getElementsByTagNameNS you need to make sure you use a namespace aware DOM by setting dbFactory.setNamespaceAware(true); on your factory used to create the DOM parser/DocumentBuilder.

answered Aug 18, 2016 at 15:49

Martin Honnen

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Ramachandran.A.G · Accepted Answer · 2016-08-18 15:21:15Z

One way you can get it to work with or without namespaces is as follows. Note that this solution uses XPATH , Although this does not solve the NPE you are getting the solution will work for the case with or without namespaces.

public static void main(String[] args) throws Exception {
    File fXmlFile = new File("C:\\DevelopmentTools\\3.CODE\\XMLWithNS.xml");
    DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance();
    DocumentBuilder dBuilder = dbFactory.newDocumentBuilder();
    Document doc = dBuilder.parse(fXmlFile);
    doc.getDocumentElement().normalize();

    XPath xpath = XPathFactory.newInstance().newXPath();
    NodeList list = (NodeList) xpath.evaluate("//*[local-name()='Cabecera']", doc, XPathConstants.NODESET);

    System.out.println("Size of the list is " + list.getLength());

}

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