Spring Meta-validator

app-context.xml

<!-- Register the meta-validator bean to MVC -->
<mvc:annotation-driven validator="validator"/>
 
<!-- Enable component scanning on the package(s) containing annotated validators -->
<context:component-scan base-package="org.example.domain.validators"/>
 
<!-- Declare the meta-validator bean -->
<bean id="validator" class="org.example.validation.annotation.ValidatorComponentAnnotationValidator">
  <property name="validators">
    <util:list>
      <!-- Enable JSR-303 bean validation -->
      <bean class="org.springframework.validation.beanvalidation.LocalValidatorFactoryBean"/>
    </util:list>
  </property>
</bean>

PersonValidator.java

@ValidatorComponent
public class PersonValidator implements Validator {
    /**
    * This Validator validates just Person instances
    */
    public boolean supports(Class clazz) {
        return Person.class.equals(clazz);
    }
 
    public void validate(Object obj, Errors e) {
        ValidationUtils.rejectIfEmpty(e, "name", "name.empty");
        Person p = (Person) obj;
        if (p.getAge() < 0) {
            e.rejectValue("age", "negativevalue");
        } else if (p.getAge() > 110) {
            e.rejectValue("age", "too.darn.old");
        }
    }
}

ValidatorComponent.java

@Target({ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Component
public @interface ValidatorComponent {
}

ValidatorComponentAnnotationValidator.java

public class ValidatorComponentAnnotationValidator implements Validator, InitializingBean {
  @Autowired
  private List<validator> validatorBeans;

  private Collection<validator> validators = new ArrayList<validator>();

  public void afterPropertiesSet() throws Exception {
    findAnnotatedValidatorBeans();
  }

  public boolean supports(Class clazz) {
    for (Validator validator : validators) {
      if (validator.supports(clazz)) {
        return true;
      }
    }

    return false;
  }

  public void validate(Object target, Errors errors) {
    for (Validator validator : validators) {
      if (validator.supports(target.getClass())) {
        validator.validate(target, errors);
      }
    }
  }

  private void findAnnotatedValidatorBeans() {
    for (Validator bean : validatorBeans) {
      ValidatorComponent annotation = AnnotationUtils.findAnnotation(bean.getClass(), ValidatorComponent.class);
      if (annotation != null) {
        validators.add(bean);
      }
    }
  }

  public void setValidators(Collection<validator> validators) {
    this.validators = validators;
  }
}