如何通过Spring Hateoas中的注释设置资源关系？

Question

Is there a way to set resource relations through annotations? I made a similar question a some time ago but i've not been clear enough. I want to have something like this:

public class UserResource {

     private String username;

     @Relation(value = "{servicebaseUrl}/classes/${value}", rel = "class")
     private String classId;

     // Getters and setters
}

And then add a message converter which would add links only if client sends Accept = application/hal+json , avoiding the fact of doing two different controller endpoints for application/hal+json and application/json . Does Spring offers something like that? I found that it actually offers this @Relation annotation(or similar one) but it seems that it is not for the same purposes.

Answer 1

No this is not possible - you would have to implement a ResourceAssembler to add links to your resources.

Usually your resources extend ResourceSupport .

class PersonResource extends ResourceSupport {

  String firstname;
  String lastname;
}

Then your create ResourceAssembler to control the creation of that resource:

class PersonResourceAssembler extends ResourceAssemblerSupport<Person, PersonResource> {

  public PersonResourceAssembler() {
    super(PersonController.class, PersonResource.class);
  }

  @Override
  public PersonResource toResource(Person person) {

    PersonResource resource = createResource(person);
    // … do further mapping and add links 
    resource.add(new Link("http://myhost/people"));
    return resource;
  }
}

See the spring hateoas documentation for details