Spring's autowired service objects

[rrkwells]

I want to call method on different service objects based on a request parameter. I have this currently..

@Controller
public class HomeController {

	@Autowired
	AService aService;
	
	@Autowired
	BService bService;
	
	@RequestMapping(value="home", method = RequestMethod.GET)
	public String checkList(ModelMap modelMap, HttpServletRequest request){
		String checkList = request.getParameter("listType");
                if("listType" == "a")
  		       modelMap.addAttribute("list", aService.getList());
                if("listType" == "b")
  		       modelMap.addAttribute("list", bService.getList());

		return "checklist";
	}
}

So I was wondering if I can use reflection kind of methodologies to call correct service object instead of if conditions.. I mean earlier, we had AService and BService implementing a common interface and instantiate correct object with reflection like this..

            String classname = (String) request.getAttribute("classname");
            Class classref = Class.forName(classname);
            Constructor c = classref.getConstructor(null);
           ServiceInterface sI = c.newInstance(null);

But with Spring, I already have the objects instantiated with AutoWiring so is there any way to achieve this?

[shoa]

Hello

I think that Factory Pattern may be better for this case for creating ASevice or BService (but you still need to use if/else).

You then use Autowired annotation (for that factory) in your controller without any logic (controller should not have "service" logic in it)

[Marten Deinum]

I really hope that that isn't the code you are using (comparing strings with == ?!)...

I would use a HashMap to map the list type to a bean name and then simply retrieve the needed bean from the application context. That way you can configure the mapping in xml.

@Controller
public class HomeController {

	private final Map<String, String> mappings = new HashMap<String, String>();
	
	@RequestMapping(value="home", method = RequestMethod.GET)
	public String checkList(ModelMap modelMap, HttpServletRequest request){
		String checkList = request.getParameter("listType");
		String serviceName = mappings.get(checkList);
		Service service = context.getBean(serviceName):
		modelMap.addAttribute("list", service.getList());
		return "checklist";
	}
	
	public void setMappings(Map<String, String> mappings) {
		this.mappings.clear();
		this.mapppings.addAll(mappings);
	}
}

If you use component-scanning to detect your Controllers this one needs to be put in xml and configure the mappings. If the mappings don't really change you could put them in a init method annotated with @PostConstruct, drawback is that you now have bean names in javacode.