Where is the @Autowired annotation supposed to go – on the property or the method?

According to the Javadoc for Autowired, the annotation can be used on “a constructor, field, setter method or config method”. See the full documentation for more details.

I personally prefer your first option (constructor injection), because the myDao field can be marked as final:

@Controller
public class MyControllear {
    private final MyDao myDao;

    @Autowired
    public MyController(MyDao myDao) {
      this.myDao = myDao;
    }

Constructor injection also allows you to test the class in a unit test without code that depends on Spring.

The second option would be better written as:

@Controller
public class MyControllear {
    @Autowired
    private MyDao myDao;

    MyController() {
    }

With field injection, Spring will create the object, then update the fields marked for injection.

One option you didn’t mention was putting @Autowired on a setter method (setter injection):

@Controller
public class MyControllear {
    private MyDao myDao;

    MyController() {
    }

    @Autowired
    public void setMyDao(MyDao myDao) {
      this.myDao = myDao;
    }

You do not have to choose one or another. You can use field injection for some dependencies and constructor injection for others for the same object.