在Jersey 1.17中指定JAXB 2上下文

Question

I'm using Jersey 1.17 on the server side to process REST requests and JAXB 2 to unmarshall the XML request content.

Context

This is the Jersey method I use. The MyDTO class uses the @XmlRootElement annotation (otherwise, I'd need to define the parameter with the JAXBElement type).

 @Path("/myService")
 @POST
 @Consumes(MediaType.APPLICATION_XML)
 public void myService(MyDTO dto) throws Exception
 {              
    // Shouldn't get this far if the XML content in the request was invalid
    System.out.println(dto);
 }

Requirement

By default, the Sun/Oracle JAXB implementation doesn't throw exceptions when the XML content has errors. For example providing a string value, say ABC, for an Integer attribute simply leaves the value as null instead of throwing an exception.

In JAXB 2 a ValidationEvenHandler can be defined. Using the following handler handler, makes the XML unmarshalling throw an exception the way I need it to.

public class UnmarshallerValidationEventHandler implements ValidationEventHandler {

        @Override
        public boolean handleEvent(ValidationEvent event) {
            // This indicates JAXB that it should continue processing only if the
            // severity level is less than error. NOTE: validation event constants
            // go in ascending order in level of severity(i.e., 0 WARNING, 1: ERROR, 2 :FATAL_ERROR)
            return event.getSeverity() < ValidationEvent.ERROR;
        }

    }

Question

How can I get Jersey to use a particular JAXBContext instance in order to use an unmarshaller with my custom validation event handler?

Alternatively, given that my application only uses JAXB in Jersey methods, defining a particular JAXBContext globally for the the JVM instance would be a good option. How could that be done?

Answer 1

Jersey Users Guide covers this in Using custom JAXBContext chapter. Basically you need to provide ContextResolver<T> like:

@Provider
public class PlanetJAXBContextProvider implements ContextResolver<JAXBContext> {
    private JAXBContext context = null;

    public JAXBContext getContext(Class<?> type) {
        if(type != Planet.class)
            return null; // we don't support nothing else than Planet

        if(context == null) {
            try {
                context = JAXBContext.newInstance(Planet.class);
            } catch (JAXBException e) {
                // log warning/error; null will be returned which indicates that this
                // provider won't/can't be used.
            }
        }
        return context;
    }
}

You can see a sample use in storage-service sample project (see JAXBContextResolver ).

Note: Instead of ContextResolver<JAXBContext> you can also provide ContextResolver<Marshaller> or/and ContextResolver<Unmarshaller> .