What is the use of @Order annotation in Spring?

Question

I have come across a glance of code which uses @Order annotation. I want to know what is the use of this annotation with respect to Spring Security or Spring MVC.

Here is an example:

@Order(1) public class StatelessAuthenticationSecurityConfig extends WebSecurityConfigurerAdapter {      @Autowired     private UserDetailsService userDetailsService;      @Autowired     private TokenAuthenticationService tokenAuthenticationService;  } 

What happen to the order of above mentioned class if we do not use this annotation?

Answer 1

It is used for Advice execution precedence.

The highest precedence advice runs first. The lower the number, the higher the precedence. For example, given two pieces of 'before' advice, the one with highest precedence will run first.

Another way of using it is for ordering Autowired collections

@Component @Order(2) class Toyota extends Car {     public String getName() {         return "Toyota";     } }  @Component @Order(1) class Mazda extends Car {     public String getName() {         return "Mazda";     } }  @Component public class Cars {     @Autowired     List<Car> cars;      public void printNames(String [] args) {          for(Car car : cars) {             System.out.println(car.getName())         }     } } 

You can find executable code here: https://github.com/patrikbego/spring-order-demo.git

Hope this clarifies it a little bit further.

Output:-

Mazda Toyota