There are 3 ways you can create an instance using @Autowired.
1. @Autowired on Properties
The annotation can be used directly on properties, therefore eliminating the need for getters and setters:
@Component("userService")
public class UserService {
public String getName() {
return "service name";
}
}
@Component
public class UserController {
@Autowired
UserService userService
}
In the above example, Spring looks for and injects userService when UserController is created.
2. @Autowired on Setters
The @Autowired annotation can be used on setter methods. In the below example, when the annotation is used on the setter method, the setter method is called with the instance of userService when UserController is created:
public class UserController {
private UserService userService;
@Autowired
public void setUserService(UserService userService) {
this.userService = userService;
}
}
3. @Autowired on Constructors
The @Autowired annotation can also be used on constructors. In the below example, when the annotation is used on a constructor, an instance of userService is injected as an argument to the constructor when UserController is created:
public class UserController {
private UserService userService;
@Autowired
public UserController(UserService userService) {
this.userService= userService;
}
}