How to consume OSGI service from non-component class

Question

I have an object that is created during the course of a request, and I'd like that object to call a service. However, when the framework calls the bind methods, it binds to its own instance of the class, not the one I want to bind to.

public class A {
   final X x;
   final Y y;

   public A(Z z) {
        this.x = z.x;
        this.y = z.y;
   }

   public String doStuff() {
        //do stuff
        //call a service
   }
}

public class B extends RestAPIServlet {

    public String method(@SlingRequest SlingHttpServletRequest request, @SlingResponse SlingHttpServletResponse response) {
        Z z = new ObjectMapper().readValue(request.getReader(), Z.class);
        return new A(z).doStuff();
    }
}

public class C extends TagSupport {

    public int doStartTag() {
        Z z = getZFromProperties();
        String res = new A(z).doStuff();
        pageContext.setAttribute("res", res);
        return super.doStartTag();
    }
}

Is there some way to call a service directly from A? Is there a preferred pattern for code reuse in the situation where you have a tag and a servlet performing the same work?

I've been asked not to make the tag/servlet implement a common interface to give A the service, nor to use a Supplier to give it access to the service through the tag/servlet.

Answer 1

BundleContext can be retrieved using the FrameworkUtil helper class and that, in turn, can be used to get to the service that you want to use. Here is an example:

BundleContext bundleContext = FrameworkUtil.getBundle(A.class).getBundleContext();
ServiceReference serviceRef = bundleContext.getServiceReference(MyService.class.getName());
MyService myService = (MyService) bundleContext.getService(serviceRef);