Set a namespace/prefix on an element if it is not set already. : Namespace « XML « Java

Set a namespace/prefix on an element if it is not set already.

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import javax.xml.XMLConstants;

import org.w3c.dom.Element;
import org.w3c.dom.NamedNodeMap;
import org.w3c.dom.Node;
 * Few simple utils to read DOM. This is originally from the Jakarta Commons Modeler.
 * @author Costin Manolache
public class Utils {
  private static final String XMLNAMESPACE = "xmlns";
   * Set a namespace/prefix on an element if it is not set already. First off, it searches for the element
   * for the prefix associated with the specified namespace. If the prefix isn't null, then this is
   * returned. Otherwise, it creates a new attribute using the namespace/prefix passed as parameters.
   * @param element
   * @param namespace
   * @param prefix
   * @return the prefix associated with the set namespace
  public static String setNamespace(Element element, String namespace, String prefix) {
      String pre = getPrefixRecursive(element, namespace);
      if (pre != null) {
          return pre;
      element.setAttributeNS(XMLConstants.XMLNS_ATTRIBUTE_NS_URI, "xmlns:" + prefix, namespace);
      return prefix;
  public static String getPrefixRecursive(Element el, String ns) {
    String prefix = getPrefix(el, ns);
    if (prefix == null && el.getParentNode() instanceof Element) {
        prefix = getPrefixRecursive((Element)el.getParentNode(), ns);
    return prefix;
  public static String getPrefix(Element el, String ns) {
    NamedNodeMap atts = el.getAttributes();
    for (int i = 0; i < atts.getLength(); i++) {
        Node node = atts.item(i);
        String name = node.getNodeName();
        if (ns.equals(node.getNodeValue())
            && (name != null && (XMLNAMESPACE.equals(name) || name.startsWith(XMLNAMESPACE + ":")))) {
            return node.getPrefix();
    return null;


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2.Namespace Attribute Event Output 1
3.Attribute with Namespace
4.Start element with namespace
5.Handling namespaces during parsing
6.Access elements from document with namespaces
7.Checks whether the supplied String is an NCName (Namespace Classified Name)
8.Add a namespace prefix definition to an element.
9.Get all prefixes defined on this element for the specified namespace.
10.Get all prefixes defined, up to the root, for a namespace URI.
11.Creates a QName instance from the given namespace context for the given qualifiedName
12.Create Namespace
13.Starting from a node, find the namespace declaration for a prefix.
14.Build a QName from the element name