如何从 application.yml 文件注入属性？

Question

I have some application.yml file:

main-prop:
  sub-prop:
    name: test
    password: test1

    data:
      prop1: 1
      prop2: 0

and classes:

abstract class abscractPropertyHolder {
    private String namePattern;
    private String categoryPattern;
    private String departmentPattern;
    private Data data;
}

@Component
@ConfigurationProperties("main-prop")
class ReconfigurationEventFilterConfig extends abscractPropertyHolder {
}

@Data
@Accessors(chain = true)
class Data {   // if my class is public - my app run successfully, otherwise fail to start (exception).
    private int prop1;
    private int prop2;

    static DatanewInstanceWithDefaultParameters() {
        return new Data().setProp1(1).setProp2(0);
    }
}

I have this exception:

Could not instantiate property type [com.test.Data] to auto-grow nested property path; 
nested exception is org.springframework.beans.BeanInstantiationException: 
Failed to instantiate [com.test.Data]: Is the constructor accessible?;
nested exception is java.lang.IllegalAccessException: 
Class org.springframework.beans.BeanUtils can not access a member of class 
com.test.Data with modifiers "public"

All classes places in the one package. I don't want to make my Data class public. How can I inject data from application.yml?

Answer 1

I fixed the problem like this:

I added the spring annotation @Autowired to the abscractPropertyHolder class and added spring annotation @ConfigurationProperties("main-prop.sub-prop.data") to the Data class.

abstract class abscractPropertyHolder {
    private String namePattern;
    private String categoryPattern;
    private String departmentPattern;
    @Autowired
    private Data data;
}

@Data
@Accessors(chain = true)
@ConfigurationProperties("main-prop.sub-prop.data")
class Data {   // if my class is public - my app run successfully, otherwise fail to 
start (exception).
    private int prop1;
    private int prop2;

    static DatanewInstanceWithDefaultParameters() {
        return new Data().setProp1(1).setProp2(0);
    }
}

Answer 2

Format yml like this:

main-prop:
    sub-prop:
      name: test
      password: test1

      data:
        prop1: 1
        prop2: 0

Answer 3

@Data makes use of @RequiredArgsConstructor . Try to define the behaviour of the @Data annotation by overriding the visibility of the constructor it creates:

@RequiredArgsConstructor(access = AccessLevel.PUBLIC)

Having @Data and @RequiredArgsConstructor , Lombok will use the access level you define.

Either this or try to define a @NoArgsConstructor .