Remove namespace prefix while JAXB marshalling

Question

I have JAXB objects created from a schema. While marshalling, the xml elements are getting annotated with ns2. I have tried all the options that exist over the net for this problem, but none of them works. I cannot modify my schema or change package-info.java. Please help

Solution 1

After much research and tinkering I have finally managed to achieve a solution to this problem. Please accept my apologies for not posting links to the original references - there are many and I wasn't taking notes - but this one was certainly useful.

My solution uses a filtering XMLStreamWriter which applies an empty namespace context.

public class NoNamesWriter extends DelegatingXMLStreamWriter {

  private static final NamespaceContext emptyNamespaceContext = new NamespaceContext() {

    @Override
    public String getNamespaceURI(String prefix) {
      return "";
    }

    @Override
    public String getPrefix(String namespaceURI) {
      return "";
    }

    @Override
    public Iterator getPrefixes(String namespaceURI) {
      return null;
    }

  };

  public static XMLStreamWriter filter(Writer writer) throws XMLStreamException {
    return new NoNamesWriter(XMLOutputFactory.newInstance().createXMLStreamWriter(writer));
  }

  public NoNamesWriter(XMLStreamWriter writer) {
    super(writer);
  }

  @Override
  public NamespaceContext getNamespaceContext() {
    return emptyNamespaceContext;
  }

}

You can find a DelegatingXMLStreamWriter here.

You can then filter the marshalling xml with:

  // Filter the output to remove namespaces.
  m.marshal(it, NoNamesWriter.filter(writer));

I am sure there are more efficient mechanisms but I know this one works.

Solution 2

For me, only changing the package-info.java class worked like a charm, exactly as zatziky stated :

package-info.java

 @javax.xml.bind.annotation.XmlSchema
 (namespace = "http://example.com",
 xmlns = {@XmlNs(prefix = "", namespaceURI = "http://example.com")},
 elementFormDefault = javax.xml.bind.annotation.XmlNsForm.QUALIFIED)

package my.package;
import javax.xml.bind.annotation.XmlNs;

Solution 3

You can let the namespaces be written only once. You will need a proxy class of the XMLStreamWriter and a package-info.java. Then you will do in your code:

StringWriter stringWriter = new StringWriter();
XMLStreamWriter writer = new Wrapper((XMLStreamWriter) XMLOutputFactory
                                                               .newInstance().createXMLStreamWriter(stringWriter));
JAXBContext jaxbContext = JAXBContext.newInstance(Collection.class);
Marshaller jaxbMarshaller = jaxbContext.createMarshaller();
jaxbMarshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, Boolean.TRUE);
jaxbMarshaller.marshal(books, writer);
System.out.println(stringWriter.toString());

Proxy class (the important method is "writeNamespace"):

            class WrapperXMLStreamWriter implements XMLStreamWriter {

                   private final XMLStreamWriter writer;

                   public WrapperXMLStreamWriter(XMLStreamWriter writer) {
                       this.writer = writer;
                   }

                     //keeps track of what namespaces were used so that not to 
                     //write them more than once
                   private List<String> namespaces = new ArrayList<String>();

                   public void init(){
                       namespaces.clear();
                   }

                   public void writeStartElement(String localName) throws XMLStreamException {
                       init();
                       writer.writeStartElement(localName);

                   }

                   public void writeStartElement(String namespaceURI, String localName) throws XMLStreamException {
                       init();
                       writer.writeStartElement(namespaceURI, localName);
                   }

                   public void writeStartElement(String prefix, String localName, String namespaceURI) throws XMLStreamException {
                       init();
                       writer.writeStartElement(prefix, localName, namespaceURI);
                   }

                   public void writeNamespace(String prefix, String namespaceURI) throws XMLStreamException {
                       if(namespaces.contains(namespaceURI)){ 
                           return;
                       }
                       namespaces.add(namespaceURI);
                       writer.writeNamespace(prefix, namespaceURI);
                   }

    // .. other delegation method, always the same pattern: writer.method() ...

}

package-info.java:

@XmlSchema(elementFormDefault=XmlNsForm.QUALIFIED, attributeFormDefault=XmlNsForm.UNQUALIFIED ,
        xmlns = { 
        @XmlNs(namespaceURI = "http://www.w3.org/2001/XMLSchema-instance", prefix = "xsi")})
package your.package;

import javax.xml.bind.annotation.XmlNs;
import javax.xml.bind.annotation.XmlNsForm;
import javax.xml.bind.annotation.XmlSchema;

Solution 4

You can use the NamespacePrefixMapper extension to control the namespace prefixes for your use case. The same extension is supported by both the JAXB reference implementation and EclipseLink JAXB (MOXy).

• http://wiki.eclipse.org/EclipseLink/Release/2.4.0/JAXB_RI_Extensions/Namespace_Prefix_Mapper

View more solutions

Comments

[HamedKhan]

Another solution mentioned here [stackoverflow.com/a/29945934/4745777][1] [1]: stackoverflow.com/a/29945934/4745777

[Junchen Liu]

in case you don't want to use cxf, import the jaxws-rtxxx.jar then using the standard jawx-ws does the same trick by code the following: class NoNamesWriter extends XMLStreamWriterFilter,

[Estevão Jordão]

you save my life

[Henno Vermeulen]

If you use xjc to generate jaxb artifacts from an xsd through a .xjb file, the package-info.java is genereated and you should not manually change it. If you use Maven to run xjc, you can use the the maven-jaxb2-plugi together with the github.com/Siggen/jaxb2-namespace-prefix. This allows to add namespace prefixes to the .xjb file (which is the input to xjc to customize how code is generated).

[BATMAN_2008]

Hi, I have been following your answers lately for my project which is building XML. I am using the Moxy to create XML using the Marshalling approach. For some reason, the generated XML takes the default namespaces such as ns0, ns1, etc even though I have provided my own custom prefix while creating the QName. Can you please have a look at this question and provide your suggestion: stackoverflow.com/questions/67553941/…