根据请求参数自动装配请求范围的bean

Question

In a spring controller, I can do the following:

@Controller
public class FooController {

    @Autowired 
    private FooServiceFactory factory;

    @RequestMapping("foo")
    public Foo createFoo(@RequestParam String kind, @RequestParam String id) {
        FooService service = factory.getFooService(kind);
        return service.get(id);
    }
}

Now, if I had lots of methods that took a kind and started with FooService service = factory.getFooService(kind); , then it would be nice to be able to move all that logic out to the controller.

Is there any other place in the controller with access to the request parameters?

Is there some way of effectively saying (I'm making up the syntax here):

private FooService service;

@Autowired 
public setKind(@RequestParam String kind) {
    service = factory.getFooService(kind);
}

Or is there some better way of encapsulating common parameters such as this?

Answer 1

If you use an instance variable to store FooService you must make sure you implement FooService with thread safety in mind. So best thing is instead of using the following style of coding.

private FooService service;

@Autowired 
public setKind(@RequestParam String kind) {
    service = factory.getFooService(kind);
}

What you can do is;

private FooService _getFooService(String kind) {
    return factory.getFooService(kind);
}

and use this inside all your controllers;

@RequestMapping("foo")
public Foo createFoo(@RequestParam String kind, @RequestParam String id) {
    return _getFooService(kind).get(id);
}

That way you can eliminate code duplication while guaranteeing thread safety.