Spring Framework

boolean supports(Class clazz)

void validate(Object target,Errors errors)

package mypack.validator;
import org.springframework.validation.Errors;
import org.springframework.validation.ValidationUtils;
import org.springframework.validation.Validator;
import mypack.model.Registration;
import mypack.model.Registration;
@SuppressWarnings("unused")
public class RegistrationFormValidator 
implements Validator 
{
@SuppressWarnings("unchecked")
public boolean supports(Class clazz) {
return Registration.class.isAssignableFrom(clazz);
}
public void validate(Object obj, Errors errors) {
Registration registration = (Registration) obj;
ValidationUtils.rejectIfEmptyOrWhitespace(errors, 
"username", "error.blank.username");
ValidationUtils.rejectIfEmptyOrWhitespace(errors, 
"password", "error.blank.password");
		
	}
}