XMLOutputFactory outputFactory = XMLOutputFactory.newInstance(); XMLStreamWriter writer = outputFactory.createXMLStreamWriter(System.out); NamespaceContext namespaceContext = new NamespaceContext() { @Override public String getNamespaceURI(String prefix) { if ("prefix1".equals(prefix)) { return "http://www.example.com/namespace1"; } else if ("prefix2".equals(prefix)) { return "http://www.example.com/namespace2"; } return null; } @Override public String getPrefix(String namespaceURI) { if ("http://www.example.com/namespace1".equals(namespaceURI)) { return "prefix1"; } else if ("http://www.example.com/namespace2".equals(namespaceURI)) { return "prefix2"; } return null; } @Override public Iterator<String> getPrefixes(String namespaceURI) { List<String> prefixes = new ArrayList<>(); if ("http://www.example.com/namespace1".equals(namespaceURI)) { prefixes.add("prefix1"); } else if ("http://www.example.com/namespace2".equals(namespaceURI)) { prefixes.add("prefix2"); } return prefixes.iterator(); } }; writer.setNamespaceContext(namespaceContext); writer.writeStartDocument(); writer.writeStartElement("prefix1", "rootElement", "http://www.example.com/namespace1"); writer.writeNamespace("prefix1", "http://www.example.com/namespace1"); writer.writeStartElement("prefix2", "childElement", "http://www.example.com/namespace2"); writer.writeNamespace("prefix2", "http://www.example.com/namespace2"); writer.writeEndElement(); writer.writeEndElement(); writer.writeEndDocument(); writer.flush(); writer.close();