Spring dependency injection with @Autowired annotation without setter

Question

I'm using Spring since a few months for now, and I thought dependency injection with the @Autowired annotation also required a setter for the field to inject.

So, I am using it like this:

@Controller
public class MyController {

    @Autowired
    MyService injectedService;

    public void setMyService(MyService injectedService) {
        this.injectedService = injectedService;
    }

    ...

}

But I've tried this today:

@Controller
public class MyController {

    @Autowired
    MyService injectedService;

    ...

}

And oh surprise, no compilation errors, no errors at startup, the application is running perfectly...

So my question is, is the setter required for dependency injection with the @Autowired annotation?

I'm using Spring 3.1.1.

Answer 1

You don't need a setter with the @Autowired, the value is set by reflection.

Check this post for complete explanation How does Spring @Autowired work