JSR 303 – Bean Validation – Let Your Bean Validate Itself

This is a simple application of my previous post whereby you can develop your own validation rule and enforcer.

The significance of this application is the use of SelfValidate interface to enable bean to define its own validation method and validator to invoke bean’s method. Typically this constraint is apply to a type, but application on field is also possible.

Constraint Annotation

@Target({ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Constraint(validatedBy=SelfValidator.class)
 
public @interface SelfValidation {
   String message() default "Self-validation failed";
   Class[] groups() default {};
   Class<? extends Payload>[] payload() default {};
}

Constraint Validator

public class SelfValidator implements ConstraintValidator<SelfValidation, SelfValidate>;
{
   @Override
   public void initialize(SelfValidationconstraint) { }
 
   @Override
   public boolean isValid(SelfValidate value, ConstraintValidatorContext validatorContext)
   {
      value.validate();
   }
}

SelfValidate interface

public interface SelfValidate {
{
   public String validate();
}