I have done the marshalling of an JAXB object (Which contains @XmlRootElement) to JSON using Jettison. But I can not convert a simple java object which has no annotations like @XmlRootElement to JSON. I would like to know "Is it mandatory to have that @XmlRootElement to marshall an object to JSON?"
I am getting the following Exception when I try to marshall the java object to Json
com.sun.istack.SAXException2: unable to marshal type "simpleDetail" as an element because it is missing an @XmlRootElement annotation
What could be the issue?
Note: I'm the EclipseLink JAXB (MOXy) lead and a member of the JAXB (JSR-222) expert group.
The JAXB (JSR-222) specification does not cover JSON-binding. Instead of using a JAXB implementation with the Jettison library, you could use EclipseLink JAXB (MOXy) that offers native JSON-binding. Below is an example.
JAVA MODEL
Foo
import java.util.List;
import javax.xml.bind.annotation.*;
@XmlAccessorType(XmlAccessType.FIELD)
public class Foo {
private List<Bar> mylist;
}
Bar
import javax.xml.bind.annotation.*;
@XmlAccessorType(XmlAccessType.FIELD)
public class Bar {
private int id;
private String name;
}
jaxb.properties
To specify MOXy as your JAXB provider you need to include a file called jaxb.properties
in the same package as your domain model with the following entry (see: http://blog.bdoughan.com/2011/05/specifying-eclipselink-moxy-as-your.html):
javax.xml.bind.context.factory=org.eclipse.persistence.jaxb.JAXBContextFactory
DEMO CODE
Demo
MOXy does not require the @XmlRootElement
annotation, and you can use the JSON_INCLUDE_ROOT
property to tell MOXy to ignore the presence of any @XmlRootElement
annotations. When the root element is ignored you need to use an unmarshal
method that takes a class parameter to specify the type you are unmarshalling.
import java.util.*;
import javax.xml.bind.*;
import javax.xml.transform.stream.StreamSource;
import org.eclipse.persistence.jaxb.JAXBContextProperties;
public class Demo {
public static void main(String[] args) throws Exception {
Map<String, Object> properties = new HashMap<String, Object>(2);
properties.put(JAXBContextProperties.MEDIA_TYPE, "application/json");
properties.put(JAXBContextProperties.JSON_INCLUDE_ROOT, false);
JAXBContext jc = JAXBContext.newInstance(new Class[] {Foo.class}, properties);
Unmarshaller unmarshaller = jc.createUnmarshaller();
StreamSource json = new StreamSource("src/forum15404528/input.json");
Foo foo = unmarshaller.unmarshal(json, Foo.class).getValue();
Marshaller marshaller = jc.createMarshaller();
marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
marshaller.marshal(foo, System.out);
}
}
input.json/Output
We see that no root element is present in the input or output.
{
"mylist" : [ {
"id" : 104,
"name" : "Only one found"
} ]
}
ADDITIONAL INFORMATION