Question

I am not sure if I am allowed to ask more than one question in a post, but here it is,

For example I have the following,

Controllers

@Controller
public class FooController{

    @Autowired
    private FooService fooService;

    @RequestMapping(value="/foo", method=RequestMethod.POST)
    public @ResponseBody foo(@RequestBody FooRequest request){
    }

}
@Controller
public class BarController{

    @Autowired
    private FooService fooService;

    @RequestMapping(value="/bar", method=RequestMethod.POST)
    public @ResponseBody bar(@RequestBody FooRequest request){
    }

}

Service

public class FooService{

    private Foo foo;

    public Foo getFoo() {
        return foo;
    }
    public void setFoo(Foo foo) {
        this.foo = foo;
    }
    public String doFoo(String str){
        return foo.doFoo(str);
    }
}

class to do the job

public class Foo{

    public String doFoo(String str){
        return (str + " is foo");
    }
}

create beans using dependency injection

<context:annotation-config/>

<bean id="fooService" class="com.myapp.service.FooService">
    <property name="foo" ref="foo"></property>
</bean> 
<bean id="foo" class="com.myapp.foo.Foo">
</bean>

My questions are:

1. I did not use @service annotation at class FooService, should I use it, and why?
2. Is this configuration thread-safe or not, and why (how is it achieved if it is thread-safe)?
3. Where can I find a tutorial about the layers (dao layers, service layer …) used in Spring design and the purpose of such a design?

Answer 1

1. Using it would simply avoid the need for declaring the bean using XML. You chose to use annotations for your other beans. I would thus also use annotations for this one.
2. Yes, it is, because Spring makes sure everything is properly wired up and initialized, with a synchronization barrier, before serving any request
3. This is a very broad question. Layering is useful for separation of concerns, testability, ability to demarcate transactions declaratively, etc.