Spring Boot Java implementation of customAnnotation

问题

I know it's a possible duplicate and I found several threads like How can I find all beans with the custom annotation @Foo? or Custom annotation is not working on spring Beans but that's not really what I do or want to do.

I want an easy validator for the length of attributes of a class. Dont tell me about @Length or @Size. They're not helpful here. I tried several solutions and none of them did work.

CustomAnnotation:

@Target({ ElementType.METHOD, ElementType.FIELD, ElementType.TYPE })
@Retention(RetentionPolicy.RUNTIME)
@Constraint(validatedBy = CheckLengthValidator.class)
@Qualifier // got this one from a solution
public @interface CheckLength {
    Class<?> className();

    Class<?>[] groups() default {};

    String message() default "List is not valid";

    Class<? extends Payload>[] payload() default {};
}

CustomAnnotationValidator (methods not implemented yet):

public class CheckLengthValidator implements ConstraintValidator<CheckLength, List<Transaction>> {

    @Override
    public void initialize(CheckLength a) {
        //get values which are defined in the annotation
        System.out.println("init");
        test = a.message();

    }

    @Override
    public boolean isValid(List<Transaction> value, ConstraintValidatorContext context) {

        for (Transaction x : value) {
            if (x.getTimestamp().length() > 30) {
                System.out.println("not valid");
                return false;
            }
        }
        return true;
    }
}

So where do I use it? At my API where all autowired repos are.

@CrossOrigin(origins = "http://localhost:4200")
@RestController
public class FileManagementRestAPI {

    @Autowired
    @CheckLength(className = Transaction.class)
    List<Transaction> transaction = new ArrayList<>();
...
}

Later this will be called to fill the list.

transaction.addAll((Collection<? extends Transaction>) csvToBean.parse());

What I tried:

I read about a solution which I later found out it is deprecated or not working anymore with CommandLineRunner and AnnotationConfigApplicationContext.

Then I've read that I have to declare it as Bean but a List here isn't a Bean or do I still need to do something with Beans? Saw something like this but didn't know what to do with it then:

public class InitBeans implements BeanPostProcessor { ... }

The error I get now:

Field transaction in com.stuff.project.apis.FileManagementRestAPI required a bean of type 'java.util.List' that could not be found.

The injection point has the following annotations:
    - @org.springframework.beans.factory.annotation.Autowired(required=true)
    - @com.stuff.project.utils.CheckLength(message=List is not valid, groups=[], payload=[], className=class com.stuff.project.entity.Transaction)


Action:

Consider defining a bean of type 'java.util.List' in your configuration.

There were several other errors when I was trying to get it running.

来源：https://stackoverflow.com/questions/59668543/spring-boot-java-implementation-of-customannotation

标签

java

Spring

annotations