How to control the initialization order of Bean in Spring interview questions

Question: How to control the order of Bean initialization in Spring?

Since the emergence of Spring 2.0, Spring provides @Order annotations to define the loading order of components.

@Order definition

@Retention(value=RUNTIME)@Target(value={TYPE,METHOD,FIELD})@Documented public @interface Order

This tag contains a value attribute, the type is integer, such as: 1, 2, etc. The smaller the value, the higher the priority.

The default attribute is Ordered.LOWEST_PRECEDENCE,

Represents the lowest priority.

It can be found through the code that the definitions of the maximum and minimum values ​​are the maximum and minimum values ​​of Inger.

Simple example

Ranks.java

RankOne.java

RankTwo.java

RankThree.java

Results.java

beans.xml

RanksClient.java

Run output:

[RankOne, RankThree, RankTwo]

Modify the RankTwo code:

@Component@Order(1)

public  class  RankTwo  implements  Ranks{ //Same code as given above}

Run output:

[RankTwo, RankOne, RankThree]