Question

I have setup a Filter for a specific set of requests i.e. */dispatch through my Guice Listener.

In this filter I want to change the binding for type BaseService (an interface containing one method ) in each request based on the Request URI. i.e. if the URI is /hello/dispatch I want BaseService to bind to HelloServiceImpl else if the URI is /bye/dispatch I want to bind to ByeServiceImpl . Both implement the BaseService .

Now somewhere in one my random class that participates in the servlet request handling I want to inject the appropriate implementation of BaseService specific to current request.

Is this possible ? How ? Thank you in advance.

Answer 1

Consider using a factory pattern for providing different types of BaseService.

public interface ServiceFactory
{
  public BaseService create(String uri);
}

public class ServiceFactoryImpl implements ServiceFactory
{
  @Override
  public BaseService create(String uri)
  {
    if(uri.equals("/hello/dispatch"))
      return new HelloServiceImpl();

    else if (uri.equals("/bye/dispatch"))
      return new ByeServiceImpl();

    return null;
  }
}

Then the factory in your module.

bind(ServiceFactory.class).to(ServiceFactoryImpl.class);

and inject this into the Request.