getting a generic List from a JAXB-RS Web service
If you consume a JAXB-RS web service using Jersey, you might encounter an issue when attempting to construct a generic List returned by the service. To get a simple object, you would simply call this code:
Client client = Client.create(); Foo foo = client.resource(url).type(mimeType).get(Foo.class);
But because of type erasure, this isn’t as straightforward for returning a generic collection. As with most APIs that require type-information at runtime for generics, you have to pass in a type token. With Jersey, you can do that by passing in a concrete instance of com.sun.jersey.api.client.GenericType.
Client client = Client.create();
List listOfFoos = client.resource(url).type(mimeType).get(new GenericType<List<Foo>>() {});
This works because when you create a construct a subclass for a generic type, the class can, via reflection, obtain its own parameterized type.
Type superclass = getClass().getGenericSuperclass(); Type myTypeArguments = ((ParameterizedType)superclass).getActualTypeArguments()[0];
This is why GenericType is abstract and you are forced to instantiate a subclass with the type information you want Jersey to know about.
Not exactly an ideal solution (reified generics would be better), but it gets the job done.
