Question

i am creating a demo application using spring mvc 3.0.I have to apply the validation over the screen.I searches on the net and found that there is mainly 2 types of validation are used with the application :-

1. Spring validations using validations Api
2. Hibernate validation using hibernate validations

Hopefully somebody give me the suggestion which one is good one to implement in the application.

Answer 1

I used both – I like the Hibernate Validation more – pretty easy to implement and pretty standard. It is automatically enabled when you have an implementation on the classpath. Here is an example:

@EmailValidator
@NotBlank
@Length(max=65)
private String email; 

Where does the message Error String comes from? In WEB-INF you must have a file called messages.properties :

NotBlank.ForgotPasswordBackingObject.email=Email address must be present

There is a standard @Email annotation, but an email such as : me@mycompany is considered valid, that is why I had to make my own @EmailValidator(changed a regex flag from * to + in the standard implementation).
There are some issues that I came across : the order of validation – which validation you want to happen first, this is done with Validation groups, but this are not possible with the @Valid annotation, for example :

@RequestMapping(method=RequestMethod.POST, value="/auth/changePassword")
public ModelAndView submitChangePasswordPage(@Valid @ModelAttribute("ChangePasswordBackingObject") ChangePasswordBackingObject backingObject, BindingResult result, Principal principal)

That is why if you have your Controller in this form (in Spring MVC for example), then you have to simulate your logic in a way – I’ve done that also.

Another cool thing that you can do it to Validate two or more fields at at time (which I found pretty useful):

@FieldMatch.List({
    @FieldMatch(firstValue = "password" , secondValue = "confirmPassword")
})
public class RequestAccountBackingObject implements Serializable {
    private String password;
    private String confirmPassword;

And the implementation :

@Target({TYPE, ANNOTATION_TYPE})
@Retention(RUNTIME)
@Constraint(validatedBy = FieldMatchImpl.class)
@Documented
public @interface FieldMatch{
    String message() default "{com.errorMessage}";
    Class<?>[] groups() default {};
    Class<? extends Payload>[] payload() default {};
    String firstValue();
    String secondValue();
    @Target({TYPE, ANNOTATION_TYPE})
    @Retention(RUNTIME)
    @Documented
    @interface List
    { FieldMatch[] value(); }
}

The other FieldMatchImpl would be :

public class FieldMatchImpl implements ConstraintValidator<FieldMatch, Object>{
    private String firstFieldName;
    private String secondFieldName;

and you need two methods implemented:

public void initialize(final FieldMatch constraintAnnotation){
    firstFieldName = constraintAnnotation.firstValue();
    secondFieldName = constraintAnnotation.secondValue();

Also:

public boolean isValid(final Object value, final ConstraintValidatorContext context){

    final String firstObj = BeanUtils.getProperty(value, firstFieldName);
    final String secondObj = BeanUtils.getProperty(value, secondFieldName);

Using org.apache.commons.beanutils.BeanUtils you can now validate the two fields.

Like this:

boolean result = firstObj.equals(secondObj);
if(!result) {
    context.disableDefaultConstraintViolation();
    context.buildConstraintViolationWithTemplate(errorMessage).addNode(firstFieldName).addConstraintViolation();
}

Other then that it has been a pleasure using the Hibernate Validation so far.