import javax.xml.stream.XMLOutputFactory;
import javax.xml.stream.XMLStreamWriter;
public class DefaultNamespaceStreamOutput {
public static void main(String[] args) throws Exception {
XMLOutputFactory outputFactory = XMLOutputFactory.newInstance();
XMLStreamWriter writer = outputFactory.createXMLStreamWriter(System.out);
writer.setDefaultNamespace("http://www.example.com/ns1");
writer.writeStartElement("http://www.example.com/ns1", "sample");
writer.writeDefaultNamespace("http://www.example.com/ns1");
writer.writeEmptyElement("inner");
writer.setDefaultNamespace("http://www.example.com/ns2");
writer.writeStartElement("http://www.example.com/ns2", "inner2");
writer.writeDefaultNamespace("http://www.example.com/ns2");
writer.writeNamespace("ns1", "http://www.example.com/ns1");
writer.writeEmptyElement("http://www.example.com/ns1", "inner");
writer.writeEndDocument();
writer.flush();
}
}