JAXB: How to ignore namespace during unmarshalling XML document?

Question

My schema specifies a namespace, but the documents don't. What's the simplest way to ignore namespace during JAXB unmarshalling (XML -> object)?

In other words, I have

<foo><bar></bar></foo> 

instead of,

<foo xmlns="http://tempuri.org/"><bar></bar></foo> 

Answer 1

Here is an extension/edit of VonCs solution just in case someone doesn´t want to go through the hassle of implementing their own filter to do this. It also shows how to output a JAXB element without the namespace present. This is all accomplished using a SAX Filter.

Filter implementation:

import org.xml.sax.Attributes; import org.xml.sax.SAXException;  import org.xml.sax.helpers.XMLFilterImpl;  public class NamespaceFilter extends XMLFilterImpl {      private String usedNamespaceUri;     private boolean addNamespace;      //State variable     private boolean addedNamespace = false;      public NamespaceFilter(String namespaceUri,             boolean addNamespace) {         super();          if (addNamespace)             this.usedNamespaceUri = namespaceUri;         else              this.usedNamespaceUri = "";         this.addNamespace = addNamespace;     }        @Override     public void startDocument() throws SAXException {         super.startDocument();         if (addNamespace) {             startControlledPrefixMapping();         }     }        @Override     public void startElement(String arg0, String arg1, String arg2,             Attributes arg3) throws SAXException {          super.startElement(this.usedNamespaceUri, arg1, arg2, arg3);     }      @Override     public void endElement(String arg0, String arg1, String arg2)             throws SAXException {          super.endElement(this.usedNamespaceUri, arg1, arg2);     }      @Override     public void startPrefixMapping(String prefix, String url)             throws SAXException {           if (addNamespace) {             this.startControlledPrefixMapping();         } else {             //Remove the namespace, i.e. don´t call startPrefixMapping for parent!         }      }      private void startControlledPrefixMapping() throws SAXException {          if (this.addNamespace && !this.addedNamespace) {             //We should add namespace since it is set and has not yet been done.             super.startPrefixMapping("", this.usedNamespaceUri);              //Make sure we dont do it twice             this.addedNamespace = true;         }     }  } 

This filter is designed to both be able to add the namespace if it is not present:

new NamespaceFilter("http://www.example.com/namespaceurl", true); 

and to remove any present namespace:

new NamespaceFilter(null, false); 

The filter can be used during parsing as follows:

//Prepare JAXB objects JAXBContext jc = JAXBContext.newInstance("jaxb.package"); Unmarshaller u = jc.createUnmarshaller();  //Create an XMLReader to use with our filter XMLReader reader = XMLReaderFactory.createXMLReader();  //Create the filter (to add namespace) and set the xmlReader as its parent. NamespaceFilter inFilter = new NamespaceFilter("http://www.example.com/namespaceurl", true); inFilter.setParent(reader);  //Prepare the input, in this case a java.io.File (output) InputSource is = new InputSource(new FileInputStream(output));  //Create a SAXSource specifying the filter SAXSource source = new SAXSource(inFilter, is);  //Do unmarshalling Object myJaxbObject = u.unmarshal(source); 

To use this filter to output XML from a JAXB object, have a look at the code below.

//Prepare JAXB objects JAXBContext jc = JAXBContext.newInstance("jaxb.package"); Marshaller m = jc.createMarshaller();  //Define an output file File output = new File("test.xml");  //Create a filter that will remove the xmlns attribute       NamespaceFilter outFilter = new NamespaceFilter(null, false);  //Do some formatting, this is obviously optional and may effect performance OutputFormat format = new OutputFormat(); format.setIndent(true); format.setNewlines(true);  //Create a new org.dom4j.io.XMLWriter that will serve as the  //ContentHandler for our filter. XMLWriter writer = new XMLWriter(new FileOutputStream(output), format);  //Attach the writer to the filter        outFilter.setContentHandler(writer);  //Tell JAXB to marshall to the filter which in turn will call the writer m.marshal(myJaxbObject, outFilter); 

This will hopefully help someone since I spent a day doing this and almost gave up twice ;)