实现Validator

public class Person {

    private String name;
    private int age;

    // the usual getters and setters...
}

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");
        }
    }
}

• supports(Class) - Can this Validator validate instances of the supplied Class?

• validate(Object, org.springframework.validation.Errors) - validates the given object and in case of validation errors, registers those with the given Errors object