JAXB: How to ignore namespace during unmarshalling XML document?

I believe you must add the namespace to your xml document, with, for example, the use of a SAX filter.

That means:

• Define a ContentHandler interface with a new class which will intercept SAX events before JAXB can get them.
• Define a XMLReader which will set the content handler

then link the two together:

public static Object unmarshallWithFilter(Unmarshaller unmarshaller,
java.io.File source) throws FileNotFoundException, JAXBException
{
FileReader fr = null;
try {
fr = new FileReader(source);
XMLReader reader = new NamespaceFilterXMLReader();
InputSource is = new InputSource(fr);
SAXSource ss = new SAXSource(reader, is);
return unmarshaller.unmarshal(ss);
} catch (SAXException e) {
//not technically a jaxb exception, but close enough
throw new JAXBException(e);
} catch (ParserConfigurationException e) {
//not technically a jaxb exception, but close enough
throw new JAXBException(e);
} finally {
FileUtil.close(fr); //replace with this some safe close method you have
}
}

Another way to add a default namespace to an XML Document before feeding it to JAXB is to use JDom:

1. Parse XML to a Document
2. Iterate through and set namespace on all Elements
3. Unmarshall using a JDOMSource

Like this:

public class XMLObjectFactory {
private static Namespace DEFAULT_NS = Namespace.getNamespace("http://tempuri.org/");


public static Object createObject(InputStream in) {
try {
SAXBuilder sb = new SAXBuilder(false);
Document doc = sb.build(in);
setNamespace(doc.getRootElement(), DEFAULT_NS, true);
Source src = new JDOMSource(doc);
JAXBContext context = JAXBContext.newInstance("org.tempuri");
Unmarshaller unmarshaller = context.createUnmarshaller();
JAXBElement root = unmarshaller.unmarshal(src);
return root.getValue();
} catch (Exception e) {
throw new RuntimeException("Failed to create Object", e);
}
}


private static void setNamespace(Element elem, Namespace ns, boolean recurse) {
elem.setNamespace(ns);
if (recurse) {
for (Object o : elem.getChildren()) {
setNamespace((Element) o, ns, recurse);
}
}
}

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 ;)

In my situation, I have many namespaces and after some debug I find another solution just changing the NamespaceFitler class. For my situation (just unmarshall) this work fine.

 import javax.xml.namespace.QName;
import org.xml.sax.Attributes;
import org.xml.sax.ContentHandler;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.XMLFilterImpl;
import com.sun.xml.bind.v2.runtime.unmarshaller.SAXConnector;


public class NamespaceFilter extends XMLFilterImpl {
private SAXConnector saxConnector;


@Override
public void startElement(String uri, String localName, String qName, Attributes atts) throws SAXException {
if(saxConnector != null) {
Collection<QName> expected = saxConnector.getContext().getCurrentExpectedElements();
for(QName expectedQname : expected) {
if(localName.equals(expectedQname.getLocalPart())) {
super.startElement(expectedQname.getNamespaceURI(), localName, qName, atts);
return;
}
}
}
super.startElement(uri, localName, qName, atts);
}


@Override
public void setContentHandler(ContentHandler handler) {
super.setContentHandler(handler);
if(handler instanceof SAXConnector) {
saxConnector = (SAXConnector) handler;
}
}
}

I have encoding problems with XMLFilter solution, so I made XMLStreamReader to ignore namespaces:

class XMLReaderWithoutNamespace extends StreamReaderDelegate {
public XMLReaderWithoutNamespace(XMLStreamReader reader) {
super(reader);
}
@Override
public String getAttributeNamespace(int arg0) {
return "";
}
@Override
public String getNamespaceURI() {
return "";
}
}


InputStream is = new FileInputStream(name);
XMLStreamReader xsr = XMLInputFactory.newFactory().createXMLStreamReader(is);
XMLReaderWithoutNamespace xr = new XMLReaderWithoutNamespace(xsr);
Unmarshaller um = jc.createUnmarshaller();
Object res = um.unmarshal(xr);

This is just a modification of lunicon's answer (https://stackoverflow.com/a/24387115/3519572) if you want to replace one namespace for another during parsing. And if you want to see what exactly is going on, just uncomment the output lines and set a breakpoint.

public class XMLReaderWithNamespaceCorrection extends StreamReaderDelegate {


private final String wrongNamespace;
private final String correctNamespace;


public XMLReaderWithNamespaceCorrection(XMLStreamReader reader, String wrongNamespace, String correctNamespace) {
super(reader);


this.wrongNamespace = wrongNamespace;
this.correctNamespace = correctNamespace;
}


@Override
public String getAttributeNamespace(int arg0) {
//        System.out.println("--------------------------\n");
//        System.out.println("arg0: " + arg0);
//        System.out.println("getAttributeName: " + getAttributeName(arg0));
//        System.out.println("super.getAttributeNamespace: " + super.getAttributeNamespace(arg0));
//        System.out.println("getAttributeLocalName: " + getAttributeLocalName(arg0));
//        System.out.println("getAttributeType: " + getAttributeType(arg0));
//        System.out.println("getAttributeValue: " + getAttributeValue(arg0));
//        System.out.println("getAttributeValue(correctNamespace, LN):"
//                + getAttributeValue(correctNamespace, getAttributeLocalName(arg0)));
//        System.out.println("getAttributeValue(wrongNamespace, LN):"
//                + getAttributeValue(wrongNamespace, getAttributeLocalName(arg0)));


String origNamespace = super.getAttributeNamespace(arg0);


boolean replace = (((wrongNamespace == null) && (origNamespace == null))
|| ((wrongNamespace != null) && wrongNamespace.equals(origNamespace)));
return replace ? correctNamespace : origNamespace;
}


@Override
public String getNamespaceURI() {
//        System.out.println("getNamespaceCount(): " + getNamespaceCount());
//        for (int i = 0; i < getNamespaceCount(); i++) {
//            System.out.println(i + ": " + getNamespacePrefix(i));
//        }
//
//        System.out.println("super.getNamespaceURI: " + super.getNamespaceURI());


String origNamespace = super.getNamespaceURI();


boolean replace = (((wrongNamespace == null) && (origNamespace == null))
|| ((wrongNamespace != null) && wrongNamespace.equals(origNamespace)));
return replace ? correctNamespace : origNamespace;
}
}

usage:

InputStream is = new FileInputStream(xmlFile);
XMLStreamReader xsr = XMLInputFactory.newFactory().createXMLStreamReader(is);
XMLReaderWithNamespaceCorrection xr =
new XMLReaderWithNamespaceCorrection(xsr, "http://wrong.namespace.uri", "http://correct.namespace.uri");
rootJaxbElem = (JAXBElement<SqgRootType>) um.unmarshal(xr);
handleSchemaError(rootJaxbElem, pmRes);