I am trying to make JAXB do not marshal empty tags when string is empty. I can make it by creating XmlAdapter where insted empty string null would be returned. But in that way, I will have to annotate each attribute with this adapter.
Is there any way to make it more global?
EclipseLink JAXB (MOXy) will let you specify the XmlAdapter for java.lang.String at the package level (I'm the MOXy tech lead):
package-info
@XmlJavaTypeAdapter(value=StringAdapter.class, type=String.class)
package example;
import javax.xml.bind.annotation.adapters.XmlJavaTypeAdapter;
StringAdapter
package example;
import javax.xml.bind.annotation.adapters.XmlAdapter;
public class StringAdapter extends XmlAdapter<String, String> {
@Override
public String unmarshal(String v) throws Exception {
return v;
}
@Override
public String marshal(String v) throws Exception {
if("".equals(v)) {
return null;
}
return v;
}
}
Root
package example;
import javax.xml.bind.annotation.XmlRootElement;
@XmlRootElement
public class Root {
private String foo;
private String bar;
public String getFoo() {
return foo;
}
public void setFoo(String foo) {
this.foo = foo;
}
public String getBar() {
return bar;
}
public void setBar(String bar) {
this.bar = bar;
}
}
jaxb.properties
To use MOXy as your JAXB provider you need to include a file named jaxb.properties in the same package as your model classes with the following entry:
javax.xml.bind.context.factory=org.eclipse.persistence.jaxb.JAXBContextFactory
Demo
package example;
import javax.xml.bind.JAXBContext;
import javax.xml.bind.Marshaller;
public class Demo {
public static void main(String[] args) throws Exception {
JAXBContext jc = JAXBContext.newInstance(Root.class);
System.out.println(jc);
Root root = new Root();
root.setFoo("");
root.setBar("");
Marshaller marshaller = jc.createMarshaller();
marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
marshaller.marshal(root, System.out);
}
}
Note
Due to what I feel is a bug in the JAXB reference implementation, the following exception is thrown if you use the version of JAXB included in Java SE 6:
Exception in thread "main" java.lang.NullPointerException
at com.sun.xml.bind.v2.runtime.output.Encoded.setEscape(Encoded.java:107)
at com.sun.xml.bind.v2.runtime.output.UTF8XmlOutput.doText(UTF8XmlOutput.java:315)
at com.sun.xml.bind.v2.runtime.output.UTF8XmlOutput.text(UTF8XmlOutput.java:299)
at com.sun.xml.bind.v2.runtime.output.IndentingUTF8XmlOutput.text(IndentingUTF8XmlOutput.java:153)
at com.sun.xml.bind.v2.runtime.XMLSerializer.leafElement(XMLSerializer.java:325)
at com.sun.xml.bind.v2.model.impl.RuntimeBuiltinLeafInfoImpl$1.writeLeafElement(RuntimeBuiltinLeafInfoImpl.java:210)
at com.sun.xml.bind.v2.model.impl.RuntimeBuiltinLeafInfoImpl$1.writeLeafElement(RuntimeBuiltinLeafInfoImpl.java:209)
at com.sun.xml.bind.v2.runtime.reflect.TransducedAccessor$CompositeTransducedAccessorImpl.writeLeafElement(TransducedAccessor.java:250)
at com.sun.xml.bind.v2.runtime.property.SingleElementLeafProperty.serializeBody(SingleElementLeafProperty.java:98)
at com.sun.xml.bind.v2.runtime.ClassBeanInfoImpl.serializeBody(ClassBeanInfoImpl.java:340)
at com.sun.xml.bind.v2.runtime.XMLSerializer.childAsSoleContent(XMLSerializer.java:593)
at com.sun.xml.bind.v2.runtime.ClassBeanInfoImpl.serializeRoot(ClassBeanInfoImpl.java:324)
at com.sun.xml.bind.v2.runtime.XMLSerializer.childAsRoot(XMLSerializer.java:494)
at com.sun.xml.bind.v2.runtime.MarshallerImpl.write(MarshallerImpl.java:315)
at com.sun.xml.bind.v2.runtime.MarshallerImpl.marshal(MarshallerImpl.java:244)
at javax.xml.bind.helpers.AbstractMarshallerImpl.marshal(AbstractMarshallerImpl.java:75)
at example.Demo.main(Demo.java:18)
