Spring 3.0 supports the new JSR-303 validation. JSR-303 standardizes validation constraint declaration and metadata for the Java platform.  The following model object has its fields annotated with JSR-303 (javax.validation.*).

@Entity(name = "partner")
@Indexed
public class Partner extends NamedEntity implements Serializable {
@Column
@javax.validation.constraints.NotNull(message = "partnerType must not be null.")
private PartnerType partnerType;
@javax.validation.NotEmpty(message = "Lanaguage can't be empty")
private String language;
@javax.validation.NotEmpty(message = "contact person can't be empty")
private String contactPerson;
}

Spring 3.0 reference guide.

explains how to configure and use JSR-303 in Spring 3.0 , but there is no clear way of doing samething in Spring Webflow.

Model validation is needed whenever you want to bind a model with data from a form submitted by a user and with JSR-303, anytime you want to valide an bean class. In this post, I am going to explain how you can configure JSR-303 validator factory in spring context as a bean and use it in both Spring MVC and Spring Webflow.

Add the following bean in your mvc application context.

<bean id="validator" class="org.springframework.validation.beanvalidation.LocalValidatorFactoryBean" />

You could also get the default validator factory in controller or validator class.

private Validator validator= Validation.buildDefaultValidatorFactory().getValidator();

1. Spring MVC

In mvc, there are several ways that you can use the above validator in your web controller:

Assuming that you using annotation driven mvc/controller.

<!-- Dispatches requests mapped to POJO @Controllers implementations -->
<bean class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter">
    <property name="webBindingInitializer">
        <bean class="org.springframework.web.bind.support.ConfigurableWebBindingInitializer">
            <property name="validator" ref="validator" />
        </bean>
    </property>
</bean>

if you are using the new mvc schema namespace.

<mvc:annotation-driven conversion-service="conversionService"  validator="validator"/>

you can also dependency inject the validator to your controller

@Autowired private javax.validation.Validator  validator

To activate the validation in your controller, you can either add @Valid annotion in the respected method as a parameter before the model object. This will atutomaticly validate the model object, and update BindingResult with constraint messages.

@RequestMapping(value = "/partner/", method = RequestMethod.POST)
public String createPartner(@ModelAttribute("partner") @Valid Partner partner, BindingResult result) {
    Assert.notNull(partner, "Partner must be provided.");
    if (result.hasErrors())
        return "partner_create";
    partnerService.persist(partner);
    return "redirect:/partner/" + partner.getId();
}

or manually activate the validation against the model.

  @RequestMapping(value = "/partner/", method = RequestMethod.POST)
public String createPartner(@ModelAttribute("partner") Partner partner, BindingResult result) {
    Assert.notNull(partner, "Partner must be provided.");       
     for (ConstraintViolation<Partner> constraint : validator.validate(partner)) {
      result.rejectValue(constraint.getPropertyPath().toString(), "",
      constraint.getMessage()); }
      
    if (result.hasErrors())
        return "partner_create";
    partnerService.persist(partner);
    return "redirect:/partner/" + partner.getId();
]

The above finishes what you need to do to utilize the new JSR-303 in spring MVC, next I will show you how to acheive samething in your webflow.