How to set noil and datatype attributes other than names in JAXB

Question

I am using JAXB with Scala, my sort code is as follows:

def marshalToXml(): String = { val context = JAXBContext.newInstance(this.getClass()) val writer = new StringWriter context.createMarshaller.marshal(this, writer) writer.toString() } 

Then for my @XmlElement(nillable = true) elements, I use the @XmlElement(nillable = true) annotation according to JAXB Marshalling with null fields . This gives me the XML output as follows:

 <name>Alex Dean</name> <customerReference xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:nil="true"/> <quantity>1</quantity> <createdAt>2011-05-14T00:00:00+03:00</createdAt> 

This is a good start, but what I really would like to marshal for these fields:

 <name>Alex Dean</name> <customerReference nil="true"/> <quantity type="integer">1</quantity> <createdAt type="datetime">2011-05-14T00:00:00+03:00</createdAt> 

In other words, I would like to remove namespace attributes and prefixes and add attribute attributes of XML attributes for all but strings. This is probably pretty simple, but I can't find it as in the JAXB documentation.

Any help gratefully received!

Answer 1

You can use JAXB with the StAX parser and do the following:

Client

Each property in your domain model will be displayed using @XmlElement(nillable=true, type=Object.class) . Setting type=Object.class will cause the xsi:type attribute to be written out.

 package forum8198945; import java.util.Date; import javax.xml.bind.annotation.*; @XmlRootElement public class Customer { private String name; private Customer customerReference; private Integer quantity; private Date createdAt; @XmlElement(nillable=true, type=Object.class) public String getName() { return name; } public void setName(String name) { this.name = name; } @XmlElement(nillable=true, type=Object.class) public Customer getCustomerReference() { return customerReference; } public void setCustomerReference(Customer customerReference) { this.customerReference = customerReference; } @XmlElement(nillable=true, type=Object.class) public Integer getQuantity() { return quantity; } public void setQuantity(Integer quantity) { this.quantity = quantity; } @XmlElement(nillable=true, type=Object.class) public Date getCreatedAt() { return createdAt; } public void setCreatedAt(Date createdAt) { this.createdAt = createdAt; } } 

XMLStreamWriterWrapper

We will write to create a wrapper for XMLStreamWriter , which will delete all the information that we do not want to write to XML.

 package forum8198945; import javax.xml.namespace.NamespaceContext; import javax.xml.stream.XMLStreamException; import javax.xml.stream.XMLStreamWriter; public class XMLStreamWriterWrapper implements XMLStreamWriter { private XMLStreamWriter xmlStreamWriter; public XMLStreamWriterWrapper(XMLStreamWriter xmlStreamWriter) { this.xmlStreamWriter = xmlStreamWriter; } public void writeStartElement(String localName) throws XMLStreamException { xmlStreamWriter.writeStartElement(localName); } public void writeStartElement(String namespaceURI, String localName) throws XMLStreamException { xmlStreamWriter.writeStartElement(namespaceURI, localName); } public void writeStartElement(String prefix, String localName, String namespaceURI) throws XMLStreamException { xmlStreamWriter.writeStartElement(prefix, localName, namespaceURI); } public void writeEmptyElement(String namespaceURI, String localName) throws XMLStreamException { xmlStreamWriter.writeEmptyElement(namespaceURI, localName); } public void writeEmptyElement(String prefix, String localName, String namespaceURI) throws XMLStreamException { xmlStreamWriter.writeEmptyElement(prefix, localName, namespaceURI); } public void writeEmptyElement(String localName) throws XMLStreamException { xmlStreamWriter.writeEmptyElement(localName); } public void writeEndElement() throws XMLStreamException { xmlStreamWriter.writeEndElement(); } public void writeEndDocument() throws XMLStreamException { xmlStreamWriter.writeEndDocument(); } public void close() throws XMLStreamException { xmlStreamWriter.close(); } public void flush() throws XMLStreamException { xmlStreamWriter.flush(); } public void writeAttribute(String localName, String value) throws XMLStreamException { xmlStreamWriter.writeAttribute(localName, value); } public void writeAttribute(String prefix, String namespaceURI, String localName, String value) throws XMLStreamException { if("http://www.w3.org/2001/XMLSchema-instance".equals(namespaceURI)) { int colonIndex = value.indexOf(':'); if(colonIndex > -1) { value = value.substring(colonIndex + 1); } xmlStreamWriter.writeAttribute(localName, value); } else { xmlStreamWriter.writeAttribute(prefix, namespaceURI, localName, value); } } public void writeAttribute(String namespaceURI, String localName, String value) throws XMLStreamException { if("http://www.w3.org/2001/XMLSchema-instance".equals(namespaceURI)) { int colonIndex = value.indexOf(':'); if(colonIndex > -1) { value = value.substring(colonIndex + 1); } xmlStreamWriter.writeAttribute(localName, value); } else { xmlStreamWriter.writeAttribute(namespaceURI, localName, value); } } public void writeNamespace(String prefix, String namespaceURI) throws XMLStreamException { if(!"http://www.w3.org/2001/XMLSchema-instance".equals(namespaceURI) && !"http://www.w3.org/2001/XMLSchema".equals(namespaceURI)) { xmlStreamWriter.writeNamespace(prefix, namespaceURI); } } public void writeDefaultNamespace(String namespaceURI) throws XMLStreamException { if(!"http://www.w3.org/2001/XMLSchema-instance".equals(namespaceURI)) { xmlStreamWriter.writeDefaultNamespace(namespaceURI); } } public void writeComment(String data) throws XMLStreamException { // TODO Auto-generated method stub } public void writeProcessingInstruction(String target) throws XMLStreamException { // TODO Auto-generated method stub } public void writeProcessingInstruction(String target, String data) throws XMLStreamException { // TODO Auto-generated method stub } public void writeCData(String data) throws XMLStreamException { // TODO Auto-generated method stub } public void writeDTD(String dtd) throws XMLStreamException { // TODO Auto-generated method stub } public void writeEntityRef(String name) throws XMLStreamException { // TODO Auto-generated method stub } public void writeStartDocument() throws XMLStreamException { xmlStreamWriter.writeStartDocument(); } public void writeStartDocument(String version) throws XMLStreamException { xmlStreamWriter.writeStartDocument(version); } public void writeStartDocument(String encoding, String version) throws XMLStreamException { xmlStreamWriter.writeStartDocument(encoding, version); } public void writeCharacters(String text) throws XMLStreamException { xmlStreamWriter.writeCharacters(text); } public void writeCharacters(char[] text, int start, int len) throws XMLStreamException { xmlStreamWriter.writeCharacters(text, start, len); } public String getPrefix(String uri) throws XMLStreamException { return xmlStreamWriter.getPrefix(uri); } public void setPrefix(String prefix, String uri) throws XMLStreamException { xmlStreamWriter.setPrefix(prefix, uri); } public void setDefaultNamespace(String uri) throws XMLStreamException { xmlStreamWriter.setDefaultNamespace(uri); } public void setNamespaceContext(NamespaceContext context) throws XMLStreamException { xmlStreamWriter.setNamespaceContext(context); } public NamespaceContext getNamespaceContext() { return xmlStreamWriter.getNamespaceContext(); } public Object getProperty(String name) throws IllegalArgumentException { return xmlStreamWriter.getProperty(name); } } 

XMLStreamReaderWrapper

We need to create a wrapper for XMLStreamReader , which will add everything that we have divided into XMLStreamWriter . This is easier to do for XMLStreamReader , as we can extend StreamReaderDelegate .

 package forum8198945; import javax.xml.stream.XMLStreamReader; import javax.xml.stream.util.StreamReaderDelegate; public class XMLStreamReaderWrapper extends StreamReaderDelegate { public XMLStreamReaderWrapper(XMLStreamReader xmlStreamReader) { super(xmlStreamReader); } @Override public String getAttributeNamespace(int index) { String attributeName = getAttributeLocalName(index); if("type".equals(attributeName) || "nil".equals(attributeName)) { return "http://www.w3.org/2001/XMLSchema-instance"; } return super.getAttributeNamespace(index); } } 

Demo

The following shows how everything integrates:

 package forum8198945; import java.io.StringReader; import java.io.StringWriter; import java.util.Date; import javax.xml.bind.JAXBContext; import javax.xml.bind.Marshaller; import javax.xml.stream.XMLInputFactory; import javax.xml.stream.XMLOutputFactory; import javax.xml.stream.XMLStreamWriter; public class Demo { public static void main(String[] args) throws Exception { JAXBContext jc = JAXBContext.newInstance(Customer.class); Customer customer = new Customer(); customer.setName("Alex Dean"); customer.setCustomerReference(null); customer.setQuantity(1); customer.setCreatedAt(new Date()); StringWriter stringWriter = new StringWriter(); XMLOutputFactory xof = XMLOutputFactory.newFactory(); XMLStreamWriter xsw = xof.createXMLStreamWriter(stringWriter); xsw = new XMLStreamWriterWrapper(xsw); Marshaller marshaller = jc.createMarshaller(); marshaller.marshal(customer, xsw); String xml = stringWriter.toString(); System.out.println(xml); XMLInputFactory xif = XMLInputFactory.newFactory(); xif.createXMLStreamReader(new StringReader(xml)); printValue(customer.getName()); printValue(customer.getCustomerReference()); printValue(customer.getQuantity()); printValue(customer.getCreatedAt()); } private static void printValue(Object value) { System.out.print(value); System.out.print(" "); if(null != value) { System.out.print(value.getClass()); } System.out.println(); } } 

Exit

 <?xml version="1.0"?><customer><createdAt type="dateTime">2011-11-25T13:36:49.095</createdAt><customerReference nil="true"></customerReference><name type="string">Alex Dean</name><quantity type="int">1</quantity></customer> Alex Dean class java.lang.String null 1 class java.lang.Integer Fri Nov 25 13:36:49 EST 2011 class java.util.Date